Luca Deseri, Ph.D. - Biosketch
· Luca Deseri is Professor of Solid and Structural Mechanics at the University of Trento in Italy.
· He also holds two positions in the USA as (i) Research Professor of Mechanical Engineering and Materials Science at the Dept. MEMS-University of Pittsburgh (effective 2016) and (ii) Adjunct Professor of Mechanics in the Dept. of Civil and Environmental Engineering And in the dept. of Mechanical Engineering at Carnegie Mellon University, Pittsburgh PA-USA.
· Luca has just been appointed “Divisional lead and Professor of Aerospace Engineering” by Brunel University London, and he will start his duties in the UK in July 2016.
Luca earned his Ph.D. in Applied Mechanics and Structural Analysis from the University of Pisa, while spending a year at Carnegie Mellon, where he subsequently did his post-doc. He was appointed assistant and then associate professor at the University of Ferrara. He moved to the University of Molise as full professor and deputy dean of Engineering. Subsequently, he became dept. head of Mechanical & Structural Engineering at the University of Trento (ranked first nationwide 12 times in the last 16 years). Luca just completed his term at the Italian directorate of Solid and Structural Mechanics and three terms as the leader of the local IUTAM society of Mechanics of Materials. He is panel member of the SNP, Society for Natural Philosophy.
Luca is the only non US scientist nominated for the election of the new Board of Director of the SES-Society for Engineering Sciences.
He is associate editor of Frontiers, sect. of Mechanics of Materials (Nature publisher, Lausanne), he is on the editorial board of: Journal of Nanomaterials, International Journal of Medical Nano Research, Journal of NanoMedicine and Application, and Mathematical Problems in Engineering. He is reviewer for several major journals, such as Nature Comm., Biomech. Modeling Mechanobiol., J. Mech. Phys. Solids, Proc. of the Royal Soc., Int. J. Non-Linear Mech., J. Elasticity, J. Nanomech. Micromech.-ASCE, J. Eur. Ceramic Soc., Math. Models Methods Appl. Sciences, Math. And Mech. of Solids, etc.
Luca has held several visiting professorships at Cornell, the University of Kentucky and Carnegie Mellon. He has been invited to visit multiple universities, including Berkeley, Caltech, Columbia NYC, Wisconsin-Madison, Nebraska-Lincoln, Ecole Polytechnique-Paris, Durham UK, Jiao Tong, Univ.Tech. Sidney, Univ. Auckland, among many others and to many specialized workshops held in major international conferences, such as WCCM, ECCM, ESMC, ASME, SES, SIAM, etc.
Luca’s main research interests range from nano-mechanics, multiscale modeling and multiphysics of structured media, including applications to mechanobiology, hierarchical materials and structures, composites, viscoelasticity, viscoplasticity, nonlinear elasticity and viscoelasticity of new mechanochromic sensors for structural health monitoring.
LUCA DESERI, PH.D.,
Full professor of Solid and Structural Mechanics,
Dept. Civil, Environmental and Mechanical Engineering,
University of Trento,
38123 Trento, Italy
Adj. professor at the Mechanics, Materials and Computing Center,
Pittsburgh PA 15213-3890 USA
Research professor of Mechanical Engineering,
MEMS-Swanson School of Engineering, University of Pittsburgh-USA
Division lead and professor of Aerospace Engineering,
MACE-College of Engineering, Design and Physical Sciences,
Brunel University London-UK
4-Nationality and citizenship
4-Major employments and achieved ranks
11-Recent talks and scientific activity
15-Teaching and relationships with students
16-Summary of the recent teaching activity
17- Experience as a professional engineer
17- Recent editorial activity
21- Description of selected publications and their main results
· Dec.2012-present Tenured Full professor of Solid and Structural Mechanics, Dept. of Civil, Environmental and Mechanical Engineering, University of Trento.
· April 2009-November 2012 Head of the Dept. of Mechanical and Structural Engineering, University of Trento.
Supervisor of the following laboratories:
Materials, Structural Testing and Dynamics
Mechanics and Automatics
Computational Solid and Structural Mechanics
Laboratory for physical modeling of structures and photoelasticity
Calibration of Force Devices (Laboratory of the “University Centre of Metrology” - C.U.M.)
Wind Turbine Test Field (CEST).
· April 2008-Nov.2012 Tenured Full professor of Solid Mechanics and Strength of materials, Dept. of Mechanical and Structural Engineering, University of Trento. On leave since August 15, 2012.
· January 2005-March 2008 Associate Dean of Engineering and Tenured Full professor of Solid and Structural Mechanics, S.A.V.A. Dept. University of Molise, Campobasso.
· 2003 Rank of Full Professor.
· November 2001–December 2004 Tenured Associate Professor of Solid Mechanics, Strength of Materials and Structural Analysis at the University of Ferrara.
· 1999 Rank of Associate Professor.
· Employments Abroad
· July 2016-onward
Divisional lead and Professor of Aerospace Engineering at the Dept. of MACE-Mechanical, Aerospace & Civil Eng.-College of Engineering, Design and Physical Sciences at Brunel University of London.
· January 2016-to be determined
Research professor of Mechanical Engineering at the Dept. of Mechanical Engineering and Material Science-MEMS, University of Pittsburgh USA.
· Febr./Oct. 2015-July 2018 Adj. professor at the Dept.s of Civil and Environmental Engineering and Mechanical Engineering, Carnegie Mellon University USA.
· January-July 2014 visiting professor at the CIT-Dept.s of Civil and Environmental Engineering and Mechanical Engineering, Carnegie Mellon University USA.
· November 2013-present full affiliate member at the Department of Nanomedicine, Houston Methodist Research Institute, 6565 Fannin St., MS B-490 Houston, TX 77030 TX-USA.
· Sept. 2012-Aug. 2013 visiting professorship at the Center for Nonlinear Analysis-Carnegie-Mellon University USA.
· August 28-September 5 2009 Visiting at the Department of Mathematical Sciences - Carnegie-Mellon University, Pittsburgh PA 15213.
· April 15-May 14 2009 Visiting at: Dept. of Mechanical Engineering, McGill University, Montreal, Canada.
· August-Sept. 2008 Rheology Research Center and Dept of Engineering Physics, University of Wisconsin-Madison, USA.
· August-Sept. 2007 Dept of Engineering Physics, University of Wisconsin-Madison, USA.
· July-August 2006 Co-op endowed Visiting Professor, College of Engineering and Department of Theoretical and Applied Mechanics (TAM), Cornell University, New York 14853.
· January-June 2005 Visiting Professor at the Center for Nonlinear Analysis and Department of Mathematical Sciences - Carnegie-Mellon University, Pittsburgh PA 15213.
· January-June 2004 Visiting Professor at the Department of Theoretical and Applied Mechanics (TAM), Cornell University, 212 Kimball Hall, Ithaca, New York 14853.
· January-June 2002 Visiting professor at the University of Kentucky, Department of Mathematics, Group of Continuum Mechanics (coordinated by Dr. Chi-Sing Man), Lexington KY.
- 1998 Postdoctoral Associate at the Center for Nonlinear Analysis-Carnegie-Mellon University, Pittsburgh-PA-USA.
- 1995 Ph.D. in Continuum Mechanics, Strength of Materials, Structural Analysis and Applied Mathematics. Consortium among the Universities of Pisa, Florence, Bari, Genova, Udine-Italy.
- 1992 Visiting graduate student at the Center for Nonlinear Analysis and Department of Mathematical Sciences-Carnegie-Mellon University, Pittsburgh-PA-USA.
- Dec.2013-present Full Affiliate member at HMRI-Nanomedicine Research Institute, Houston Methodist Hospital
- September 2013-present Panel member of the SNP, Society for Natural Philosophy;
- Sept. 2009-Dec. 2013: Member of the board of five coordinators of the Italian academic area of “Solid and Structural Mechanics”, s.s.d. ICAR/08;
- March 2008-Dec. 2013 Group of Mechanics of Materials, Italian Association of Theoretical and Applied Mechanics (AIMETA), national coordinator since March 2008 together with R. Massabò (Genova) and P. Vena (Milano);
- ASME American Society of Mechanical Engineering;
- Italian Group of Fracture, IGF;
- National Group of Applied Mathematics-Section of Engineering Mechanics, GNFM-ITALY.
- ISIMM, International Society for the Interaction between Mechanics and Mathematics.
- February 2005-December 2006 Member of the panel of reviewer of the project X-Fast, Advanced Space Transportation, European Space Agency (ESA), ESTEC, AB-Technologies. Project Manager: Dr. Eng. Biagio Ancarola.
My scientific interests are in the broad area of multiscale phenomena in Solid Mechanics and related areas of Engineering Sciences. My recent studies can be summarized in the sequel.
-Effective properties of micro and nano composites for standard and advanced engineering applications
The necessity of detecting residual stresses in composites is often a crucial issue in order to be able to prevent undesired stress concentrations giving rise to local damage, debonding, pull out, etc. Although non-destructive experimental techniques already applicable to detect residual stresses in metals, ceramics and other materials may be useful for resolving such stresses in composites, very little is known about their actual influence on the effective properties of the composite. This research devotes attention to this problem by focusing on composites formed by randomly distributed ’small’ inclusions in a matrix; the theory is developed for any shape although the examples are worked out for spherical inclusions or voids. In particular, it is shown that the “danger” of relatively small residual stresses with very rapid spatial oscillations may result either in a magnification of the RVE size with respect to the un-prestressed case or on its blow-up. Henceforth, in these cases there is no RVE that can be singled out to describe the effective response of the composite in a local form, ultimately suggesting the intrinsic non-local overall behaviour induced by the presence of residual stresses.
This ongoing project also involves a rigorous procedure allowing for finding effective constitutive equations for viscoelastic random composites allowing for capturing their space-time non-local behaviour; residual stresses are taken into account and the frequency dependence of the RVE-size is discussed.
Indeed, residual stresses induced by experienced past strain histories are known to be present in viscoleastic and viscoplastic aggregates employed in structures and in mechanical components Unfortunately, past strain histories are, in general, not known. When further loading is imposed, the generated stress is a combination of the effects cause by the strain process directly associated to such loading and the residual stress generated by the past experienced history. Residual stresses are known to relax after some time, which may not be negligible when compared to the duration of future strain processes induced by applied loading. Obviously, self-balanced residual stresses are present even without imposing further loading. The determination of the relaxation or creep properties of such materials are necessary for any viscoelastic analysis. Corresponding tests are performed on virgin samples of single phased materials or composites, usually samples are thermally annealed to eliminate memory induced effects and then subject to testing. Nevertheless, such procedures may be neither possible nor practical in most of the real situations, so that the performances of viscoelastic components and structures remain influenced by existing memory induced residual stresses.
Incidentally, a novel and phenomenological-based stress-like variable was introduced in the past by the candidate to single out the "state" of a viscoelastic material. The state variable was found by noting that different past strain histories are equivalent if they produce the same response under any (and the same for each of the histories) further imposed strain process with arbitrary duration. The part of the stress which is common to all the different histories does resemble information on the response to further zero strain processes. Indeed, when one singles out such a process, the state variable coincides with the residual, and relaxing, stress mentioned above. There are significant advantages on choosing such a variable. First of all, this notion of state variable is, in general, free of the knowledge of the particular experienced past strain: this is very important when it comes to finding the effective response of a random viscoelastic composite. The other advantage is the fact that relaxing residual stresses may be detected by direct measurements.
A related focus of the research is about Nano-composites. Emphasis on nano-reinforcements of several kinds on polymeric/soft matter matrices are of great interest for many cutting edge applications. Indeed the presence of soft matter and nanometric-reinforcements yields exceptional properties to the mixture such as high strength, toughness, and ductility that often times are not present in composites at the same time. This is very similar to the behavior of many biological structures as nacre, dentin and mineralized bone tissues where the presence and the particular staggers of soft proteins (chitin or collagen) and mineral nano-reinforcements (aragonite or hydroxyapatite) yields the macroscale properties of nacre shells or mineralized biological tissues. Experimental measures of the properties of such materials are usually conducted at macroscale to provide possible relations among the specific physical/mechanical parameters (strength, ductility, relaxation, thermal conductivity/adhesive properties) and the characteristics of the compostites as the presence of cross-links, size and shape of reinforcements, percentage of nano-reinforcements and so on. In this setting the prediction of the behavior of the composite is of primary importance to provide an optimized design for their applications. For instance, in this regard the candidate has formed a research team which has worked out relationships among the relaxation properties of mineralized bone tissues, composed at nano-scale by a staggered array of mineral platelets and collagen proteins.
In this chapter of my research it also falls my brand new studies on the nonlinear elasticity and viscoelasticity of novel optomechanical/mechanochromic strain sensors applied to structural health monitoring (SHM). This is in collaboration with Dr. Daniele Zonta, leader of the SHM group of my dept. in Trento and the Italian CNR-IFN of Photonics, led by Dr. Maurizio Ferrari.
The researches above belong to projects of a team led by the candidate which include Francesco Dal Corso and Pietro Pollaci, Mech.& Structural Engineering at the University of Trento, Emanuela Bosco, Math. Dept.-College of Engineering-Brescia and Eindhoven University-Materials Technology. A collaboration with M. Zingales (Palermo, Italy) and W. J. Drugan at the Dept. of Engineering Physics at the University of Wisconsin-Madison is also foreseen. Collaborations with computational and experimental scientists are desirable.
- Bioinspired and biological structures
Bio-inspired materials, basically, are defined by their morphological/functional likeness to structures and biological tissues in nature. The common feature to all biological tissues is represented by the presence of a multi-scale structure that can be detected both at the nano-scale than to the micrometric scale up to the macro-scale. In this perspective, even synthetic materials artificially produced and not existing in nature, but with a highly developed multi-scale hierarchical structure, and with high functionality, are commonly known as bio-inspired materials. The relationships among the features of the constituents forming the structure of the material, their morphological and structural organization, and their properties exhibited at the macro-scale are the key focus of the research. Those are essential information for the study of novel materials with enhanced mechanical properties inspired from biological structures. The research activities will be conducted along two fundamental directions:
1) The formulation and development of theoretical models of type analytical/numerical able to predict the mechanical behavior at the macro-scale taking into account the presence of an internal structure of the material.
2) The study of various nano/micro structured materials, like ice, carbonatic matrixes admixed by the addition of nano-particles (nano-tubes, nano-spheres) in order to obtain specific functionality, etc.
Applications of the theories of SDs (Structured Deformations), OS (Objective Structures) and hierarchical scalings (e.g. Fractional Calculus applied to Multiscale Mechanics), will be performed in collaborations with D.R.Owen and K. Dayal (Carnegie Mellon), M. Zingales and M. Di Paola (Univ.Palermo, Italy), P. Pollaci (Univ.Trento, Italy) as well as with computational scientists of the perspective host institution.
Furthermore, specific interests are foreseen in mineralized biological tissues providing coarsing-load capacity in mammaliam organisms. In this regard the mechanical behavior of bones, tendons, ligaments and other highly functionalized tissues are very important per-se but also to the extend to conceive artificial structures with enhanced structural performances. These features involve similar stiffness, strength and toughness among in vivo and artificial devices. Furthermore, “self-healing” structures may be conceived by forming hereditary artificial materials similar to mineralized biological tissues. For the latter this is indeed a crucial aspect for the speed of bone reformations. In such systems macroscopic hereditariness is known to be fit by power-law relaxation laws, which are associated to systems of “spring-pots”. Recently the candidate has shown that the power-law hereditariness experienced at the macroscale is related to the presence of the hierarchic self-similar properties of bone tissues from the nano-scale. Indeed the nanoscopic structure of bone material is represented by almost rigid mineral platelets interconnected by soft collagen matrix. This assembly may be found almost at any observation scale and therefore it corresponds to a fractal sequence of mechanical objects. As we introduce a power-law decay with the observation scale of the mechanical properties of the collagen matrix according, in example, to the anomalous scaling of the cross-sectional area of the specimen, a power law decay at macroscale is experienced.
The topic discussed above will be also useful to study the mechanics of ice as a self similar structure and its time dependent behaviour.
Implications of a recent model developed by the candidate for the mechanical behavior of biological membranes are exploited by means of a prototypical problem, which permits to show that the knowledge of the stretching energy density – i.e. the membrane constitutive response with respect to local variations of area completely regulates their spatial behavior during ordering-disordering phenomena. For biomembranes with coexistent fluid phases, the corresponding values of surface tension, line tension, bending moduli and the thickness profile inside the boundary layer where the order-disorder transition is concentrated are calculated. Furthermore, thickness changes in cell membranes may be initiated by conformational changes of some domains forming membrane receptors responding as a second messenger to external ligands. Unfortunately, thinning may indicate the possibility of fracture of the membrane, leading to loss of functionality of the cell aggregate. The mentioned response may be directly linked to the coupling of conformational and mechanical effects, the former arising in some of the domains cited above. Stationarity of a new Helmholtz free energy, accounting for receptor density and conformation field and strain gradients in membrane thinning or thickening, is investigated. The density of active receptors is directly related to the conformation field above and it enters as a source term in the resulting balance equation for the membrane stress. Henceforth, balance laws for the cAMP transporters and for the flux of active receptors, coupled with the former, must be supplied together with a balance between the diffusive powers to yield “sink” due to the outgoing flux provided by the transporters.
This work naturally continues the studies on Mechanics of nano-biological systems and it will be done together with G. Zurlo (LMS Ecole Polytechnique Paris), L. Lunghi and G. Valacchi, Dept. of Biology and Evolution, Div. Of General Physiology, University of Ferrara, Italy, M. Fraldi, Interdisciplinary Center on Biomaterials (CRIB), Università di Napoli Federico II, Napoli-Italy.
Further developments are foreseen through the synergic application of both the Theory of Objective Structures (OS) and the Field Theory of Structured Deformations (STDs). This may be done together with K. Dayal (CEE-Carnegie Mellon University) for the OS part. Application of the OS will deliver information from the smaller length scale, including spontaneous curvature, of the individual monolayer, possibly owing insights on the response to changes of the gaussian curvature of each layer. In particular for biological structures such as liposomes, planar bilayers, cell membranes, the main ingredient is to have some averaged quantities describing the underlying geometrical changes at the sub-macroscopic level resembling information about the finer structure of the matter. This has the big advantage of delivering the key features of the finer structure without the need of carrying along a large number of variables and it is necessary to deliver effective Helmholtz free energies characterizing the response of the overall system. The latter may, in fact, depend on the macroscopic deformation through its gradient, although the response may be affected by disarrangements occurring at the sub-macroscopic level (such as slips, voids, separation of matter). The theory of STDs is the right geometrical environment for the kinematics of the overall structure. Such a theory is essentially a two-field approach. Indeed, besides the deformation gradient F, a tensor field G is utilized to provide an average measure of the local deformation. An STD is identified with the pair (F, G) for which it is proved that macroscopically volume changes without disarrangements (measured through detG) are always less than or equal that the macroscopic volume ones, measured through detF. This tantamount to the ”accomodation inequality” for STDs, which states that interpenetration of matter cannot occur even at the sub-macroscopic level. For G an identification relation has been derived in which it is shown that at any fixed material point such tensor may been obtained as a limit of a volume average of gradients of piecewice smooth deformations (evaluated away from disarrangement sites) converging to the given STD. The explanation above suggests that a macro-to-sub-macroscopic formulation may deliver new insights on sub-structured bodies starting from an effective Helmholtz free energy through the new field theory for first order STDs proposed in by the candidate in 2003 and expanded in more recent work. This theory may provide an encouraging new approach which, thanks to the information delivered by the application of the theory of OS, will be investigated specifically for applications involving biological and bio-inspired structures at the appropriate length scales.
The approach just described may allow for introducing a very significant novelty in the way in which the theory of OS is actually utilized. This has to do with the availability of a multiscale geometry provided by STDs, which may allow to overcome the traditional Cauchy-Born rule, where the underlying lattice is convected through the gradient of macroscopic deformation F to coarse-grain in the far-field. The multiscale kinematics allows to identify G as the ”carrier” of the underlying perfect ”lattice”, thereby allowing for modifying the usual Cauchy-Born rule through the averaged measure of deformation gradient without disarrangements G. Henceforth lattice vectors may be convected through such a local measure of deformation, by allowing for the interplay between G and F to be governed by the resulting energetics, the balance laws and the remaining conditions. Bringing together the finer scale through OS with the target of providing effective response of biological structures through STDs may allow for considering electro-mechanical coupling. Indeed, OS may provide information about electric fields generated by charge distributions at the atomistic level and, also, an extension of the field theory for STDs may be worked out to include electrostatics. The latter, together with changes in temperature and mechanical stress, may in fact regulate many complex biological systems. In relatively simple biological systems such as lipid membranes, not only flexo-electricity may be accounted for, but also further work may conceivably done to explore electro-mechanical coupling. Indeed, when phase transitions occur to modify the order exhibited by the lipids, thinning or thickening are observed due to the conformational changes of such units . henceforth, dipoles distances are not constants in such structures and this, in turn, may vary the overall electrical response. particular attention may be devoted to the modeling of the couple behavior of lipid tubulus which may possibly lead to the developments of new classes of composite biomaterials.
Other developments about impacts of the current research on bio-inspired materials are foreseen with prospective collaborations with M. Ferrari (Nanomedicine Inst., The Methodist Hospital Research Institute and Biomedical Engineering in Medicine Weill Cornell Medical College of Cornell University), N. Pugno (University of Trento and FBK Italy, MIT) as well as K. Bertoldi (Harvard), M. Morandotti, G. Leoni, I. Fonseca and D. R. Owen (Carnegie Mellon). Interactions with the perspective host institution are also foreseen, and collaborations with computational and experimental scientists are desirable
- A new multiscale field theory for novel and classical materials exhibiting microstructures; the approach is established in the framework of the theory of structured deformations: together with D. R. Owen, Center for Nonlinear Analysis and Dept. of Mathematical Sciences, Carnegie-Mellon University, Pittsburgh PA, USA. This framework will be extended to study the behaviour of large arrays of metamaterials, with regards of their acoustic and mechanical behaviour.
- A new approach to crystalline plasticity: the influence of microstructures on the macroscopic behavior of metallic crystals undergoing finite deformations is interpreted with the new tools provided by the theory of structured deformations, together with D. R. Owen (see above).
- Constitutive equations suitable for describing both plastic and rate effects at large deformations in polymers and metals;
- Wrinkling under tension of thin elastic sheets: ongoing research together with E. Fried, formerly Dept. of mechanical, Aerospace and Structural Engineering, Washington University in St. Louis, and the Dept. of Mechanical Engineering, Mc Gill University, Montreal, Canada, now at the Department of Mechanical Engineering, University of Washington, Seattle USA (firstname.lastname@example.org);
- Theory of viscoelasticity and viscoplasticity and its applications:
-the explicit form of the maximum recoverable work (minimal free energy) in linear viscoelasticity, together with G. Gentili (deceased in the year 2000) and M. Golden, head of the School of Mathematics, Dublin Institute of Technology, Ireland;
-the analytic form of the minimal free energy for continuum spectra viscoelastic material: together with M. Golden (see above);
-free energies, state and St. Venant’s principle in viscoelasticity: together with G. Gentili and M. Golden, see above.,
- Modelling for cold and dry compaction of ceramic powders, joint grant with D.I.M.S.-Trento. Reference person for S.A.C.M.I. Imola S. C.: Dr. Eng. Alessandro Cocquio (Alessandro_Cocquio@sacmi.it). A related project has been done with TRW-Automotive through the years 2005-2008: the subject of the work remains classified. Reference person for TRW Automotive: Dr. Eng. Bruno Bertagna (Bruno.Bertagna@TRW.COM)
July 2016 International Center of Mechanics-CISM-course “The Role of Mechanics in the Study of Lipid Bilayers”, together with D.J.Steigmann (Berkeley), M.Deserno (Carnegie Mellon), E. Fried (Okinawa-JP), J. Guven, (Univ. Mexico), T.J.Healey (Cornell)
November 2015 ASME-IMECE World Conf. workshop 52622, Houston TX
Brunel University of London, Mechanical, Aerospace and Civil Eng.-seminars
Aalto University-Espoo, Finland, Mechanics seminars
July 2015 Invited speaker at:
-ESMC-EUROMECH 2015-workshopon Cell Mechanics, talk on “Frequency-Based Mechanical Targeting Of Healthy and Cancer Single-Cell Systems“, Madrid;
-CERMODEL- conf. Talk on “Mechanics of hierarchical ceramics”., Europ. J of Ceramics
June 2015 Invited speaker at the Special Session #36 at the AMS-EMS-SPM, Porto
February 2015 Invited keynote at EUROMECH Colloquium 560: “Mechanics of Biological Membranes”, Ascona (Switzerland), ETH Zurich facility
SES-ASME annual meeting (Purdue IN):
- invited talk at the mini-symposium on Mechanobiology of cells and tissues (ref. A Agrawal UHouston, M Taher A Saif IL,T Lele U FL))
- invited talk at the mini symposium Soft Materials and Structures (ref. P. Reis, K Bertoldi, Harvard)
August 2014 Invited speaker at the UTA_CMU/MAT/0005/2009 workshop, Instituto Superior Técnico-Lisbon
July 2014 WCCM-ECCM-IACM-Eccomas 2014 Invited talk at the MMCM5-Multiscale and Multiphysics Modelling for Complex Materials
June 2014 Invited lecture at the ICFDA-International Conference on Fractional Differentiation and its Applications, Catania-Italy
January-April 2014 Invited talks at
- University of Pittsburgh, Dept. of Civil Engineering
- Carnegie Mellon, Dept. of Mechanical Engineering
- Carnegie Mellon, Civil and Environmental Engineering
- Carnegie Mellon, Center for Nonlinear Analysis
-Department of Nanomedicine, Houston Methodist, Health Science Center, Houston TX-USA;
Sept. 2012-Nov. 2013: Invited talks at:
-Durham University UK, School of Engineering and Computing Sciences;
-University of Michigan Joint Institute Jong Tong Shanghai (ref. O. A. Bauchau) ;
-SES meeting at Brown University, workshops on (i) nano-biomechanics, (ii) in honor of the SES medalist D. Steigmann;
-Columbia University, Dept. Mechanical Engineering (ref. J. Kysar);
-APS Workshop 'Soft-Matter, Biology, & Bioinspiration’ Baltimore, March 2013 (ref: C. Majidi)
-University of Lincoln Nebraska, Mechanical Engineering, Group of Solid Mechanics (ref. E. Baesu)
-Department of Nanomedicine at the University of Texas Health Science Center, Houston TX-USA;
- Department of Mathematical Sciences, Indiana University and Purdue University (ref. G. Guidoboni);
-Civil Engineering and Mechanics, Columbia University NYC (Ref. R. Betti);
-Caltech, California Institute of Technology, Graduate Aerospace Laboratories (ref. C. Daraio;
-University of Pittsburgh, Mechanical Engineering and Applied Mathematics (ref. A. Vainchtein);
-CNA-Center for Nonlinear Analysis-Carnegie-Mellon University (ref. D. R. Owen and I. Fonseca).
May 2012 Invited talks at University of Naples and University of Bologna, Italy
July 2012 8th European Solid Mechanics Conference, Graz: TU Graz
Aug 2011 Invited seminar at the Department of Engineering Sciences and Auckland Bioengineering Institute, University of Auckland
Nov 2010 Invited talk at the CNA seminar series, Center for Nonlinear Analysis-Carnegie-Mellon University USA
July 2010 Eccm 2010-Invited talk Workshop on Modeling of Complex Materials
Apr 2010 Invited talk at the Canadian Research Math. workshop on biovesicles, Montreal-Quebec-Canada
Febr 2010 Ecole Polytechnique Paris-LMS, France (talk)
September AIMETA 09-Ancona (talk)
August visit at the CNA-CMU Pittsburgh PA
July ISDMM09-Trento (talk)
January GMA09-Polytechnic School-Milan, Italy (talk)
Opening colloquium at the RRC (Rehology Research Center) University of Wisconsin-Madison-WI-USA (reference: Prof. Dr. Eng. A. J. Giacomin, Chair, RRC).
July Invited speaker at the symposium on "Recent Developments in the theory and applications of Structured Deformations, Canada (reference: Prof. Dr. D. R. Owen;
May Invited speaker at the Workshop on "Modelling biomembranes and biological structures", USA (reference: Prof. Dr. Eng. T. J. Healey.
February Visiting professor at the Department of Mechanical, Aerospace and Structural Engineering, Washington University in St. Louis, MO, USA (ref. Prof. Dr. Eng. E. Fried, now at the Dept. of Mechanical Engineering, Mc Gill University, Montreal-Canada);
October Invited speaker at the 44th Society of Engineering Sciences Conference-Bernard Coleman symposium, Texas A. & M., College Station TX, USA.
July-September Visiting professor at the:
-Department of Mathematical Sciences and Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh PA 15213-3890 USA ;
-Department of Engineering Physics, University of Wisconsin, Madison, USA.
January-February Invited lectures from the following institutions:
Dept. of Mechanical Engineering, University of Wisconsin, Madison, WI, USA;
Dept. of Mathematical Sciences, Carnegie-Mellon University, Pittsburgh, PA, USA;
Theoretical and Applied Mechanics Dept. (TAM) Cornell University, Ithaca, NY, USA;
Dept. of Mechanical Engineering, Washington University, St. Louis, MI, USA.
July-August Co-op endowed Visiting Professor, College of Engineering and Department of Theoretical and Applied Mechanics (TAM), Cornell University, 212 Kimball Hall, Ithaca, New York 14853, USA.
March-April Invited lectures from the following institutions:
Department of Mathematical Sciences and Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh PA Aerospace and Mechanics Dept., University of Minnesota, Minneapolis MN, USA (Host: Prof. Dr. Eng. R. D. James),
Dept. of Mechanical and Aerospace Engineering, Washington University, Saint Louis MO, USA,
Theoretical and Applied Mechanics Dept., Cornell University, Ithaca NY, USA.
January-June Invited Visting University Professor, Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA.
June-September Visiting professor, Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA;
January-June Invited seminars in the following institutions:
-Aerospace Engineering and Mechanics, University of Minnesota, MN-USA;
-Theoretical and Applied Mechanics Department (TAM), Cornell University, Ithaca, NY, USA;
-Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA;
-University of Kentucky, Department of Mathematics (Group of Solid Mechanics), Lexington KY-USA.
December Invited speaker at the Cofin 2002 Meeting, conference of the national grant "MMSM", national coordinator Prof. P. Podio-Guidugli, Bressanone, ITALY;
November Invited speaker at the international conf. Colloquium Lagrangianum 2003, Montpellier, France;
September Invited speaker at the SNP Meeting/IMA PI Conference: MultiscaleEffects in Material Microstructures and Defects, University of Kentucky, Lexington KY-USA.
August Visiting at the Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA. Invited seminar, A new approach to texture and plasticity of polycrystals.
February-March Visiting at the Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA.
August-September Visiting at the Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA.
July Invited lecturer at the CISM Course: Multiscale Modeling in Continuum Mechanics and Structured Deformations, International Center for Mechanical Sciences, Udine-Italy, July 15-19, 2002. Lecturers: D.R. Owen (USA), F. Marigo (FRA), M. Silhavi (Ceck Rep.), Le (D), G. Del Piero and R. Paroni, Italy.
August Visiting at the Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA. Invited seminar, A new approach to texture and plasticity of polycrystals.
February-March Visiting at the Center for Nonlinear Analysis, Carnegie-Mellon University, Pittsburgh-PA, USA.
September Invited speaker c/o Meeting on Dissipative Effects in Mechanics”, Society for Natural Philosophy Meeting, University of California-Berkeley, USA (ref. Prof. Dr. D. Steigman)
June Invited speaker c/o Euromech2000, minisymposia “Strain localization and phase transitions”, Metz, FRA (ref. Prof. Dr. C. Faciu, Cristian.Faciu@imar.ro).
February Invited seminar c/o Graduate Aerospace Laboratories, California Institute of Technology, Pasadena-CA- USA (host: Prof. Dr. Eng. M. Ortiz).
2006-present: S.A.C.M.I. Imola S. C. Ceramics grant on "Modelling for cold and dry compaction of ceramic powders", joint grant with D.I.M.S.-Trento (45 K€/year)
2007-2012: TRW Automotive grant. The subject of the work remains classified. (35K€/year).
FROM PUBLIC SOURCES
2009-2013 PRIN-competitive research funding program from the MIUR-Italian Ministry of University and Research (46 K€/year per each unit)
2012-2015 FP7project INTERCER2 - Modelling and optimal design of ceramic structures with defects and imperfect interfaces ", FP7-PEOPLE-2011-IAPP (2,5 M€)-member
2013-2017 "HOTBRICKS - Mechanics of refractory materials at high-temperature for advanced industrial technologies" FP7-PEOPLE-2013-IAPP; total funding 1.1 MEuro (funding to the research unit: 678 kEuro)-member
2011-2012 NANOSENSE, from the Italian Ministry of Foreign Affairs and the Italian Ministry of University, Research and Education (55 K€)-member
2007-2008: Chair and coordinator of INTERREG-Card-Phare Meetigation of Seismisk Risk and Modelling", Croatia-Molise program (1,5 M€/year)
2003-2006: Member of the National Grant "Modeling of Polycristalline Materials", in Applied Mathematics, Solid Mechanics, Mechanical Engineering and Material Science and Engineering (32 K€/year)
2014-present: BioNanoScaffolds for Bone Tissue Engineering, together with TMHRI-Department of Nanomedicine, The Methodist Hospital Research Institute, Houston, TX USA
2014-present: Mathematical modeling of the mechanics and multiphysics of BioNanoScaffolds for Bone Tissue Engineering, with ISTEC-CNR Faenza Italy 150K€/year, 3 years
2016-2019: Mathematical modeling of the biomechanics regulation and pharmacologic antagonism of the minimal persistent flogosis in respiratory epithelial cells, 250K€/year,Campania Bioscience Horizon2020
A little over six years ago, a couple of years after winning a national competition to become full professor in Italy, the University of Molise hired me under the strategic plan to build the brand new College of Engineering. Immediately after, I led the start-up process, with the tasks of writing the proposal for the College under construction, including the hiring strategy, the frame for the students plan at all levels and the growth plan. During my permanence there, I was acting associate dean, delegate of the rector for the relationships with industries and I was also in charge of representing the College at the “COPI” (Union of the Italian Engineering Colleges) in Rome instead of the Dean.
During that time I led an INTERREG project (EU funded) of the order of six hundred thousand euros involving the areas of Seismic Engineering, Solid and Soil Mechanics (Molise was the coordinator).
In the 2008 I was invited to be appointed by the College of Engineering at the University of Trento, the n°1 college of engineering in Italy in ten years out of the last twelve, where I joined the DIMS-Dept. of Mechanical and Structural Engineering. Less than a year later, he was elected as head of this institution. Given the troubles suffered by such a department in the previous years, my plan was to push forward issues like (i) outsourcing coming from scientific and industrial grants and (ii) increasing international visibility in terms of publications and international relationships.
Organizational skills may be deduced by the fact that a particularly cohesive environment for faculties and students was built in Trento over the last year and a half.
Although the department. used to have an average balance of seven hundred thousand euros/year, the first full year balance after my guidance jumped up to 3 millions euros/year. It is worth noting that the funding from the central government remained constant through the years (of the order of fifteen percent of the total). I think I gave strong motivations to the members of my department that led to a rapid improvement in both strategic directions and they seem to have the same trend for the upcoming year.
A good indication of having motivated colleagues is that after twenty five years from the foundation of the department, I was able to organize the first departmental conference ever held. This which was open to academicians, students and industries.
Managing the following laboratories
Materials and Structural Testing
Mechanics and Automatics
Computational Solid and Structural Mechanics
Laboratory for physical modeling of structures and photoelasticity
Calibration of Force Devices (Laboratory of the “University Centre of Metrology” - C.U.M.)
Wind Turbine Test Field (CEST),
Has been a challenging and successful work. Particular emphasis may be put on laboratories which are more related to my scientific interests, such as Materials and Structural Testing, lab. for physical modeling of structures and photoelasticity and Computational Solid and Structural Mechanics, which are leaders across Italy and top notch across Europe.
Among the issues I pursued during my term there has been a successful improvement of the graduate program and the increase of interdisciplinary research which also tied together academia and industries from Italy and foreign countries.
Interpersonal relationships are and have been also very important for me. In particular, good relationships with colleagues, students and people from industries and public administrations are key features that I pursued from the beginning of my career.
Faculties normally get along very well with me. For instance, the main reason why I have been elected as head of a department in Italy relies upon good personal relationships as well as the capability to compromise and let people to agree about general principles. Leading teams, getting to the goals by keeping a good atmosphere represents a high gain for an academic environment.
A few years after my Ph.D., which included a period of time at Carnegie-Mellon University, where I also spent a Postdoc, I established a long-standing network of international connections which actually is evolving year after year.
The academic network, mainly includes prestigious scientists and institutions in the USA, where I had a few visiting positions and systematic collaborations though the years; Canada and Europe are also part of my network. Aside from this, I also have good relationships with international industries in the field of automotive, production of machines for pressing ceramics, etc.
My experience ranges from the Italian to the American system, where I taught with success at both levels. I was essentially in charge of courses in basic and advanced (including special topics) Solid Mechanics, Statics, basic and advanced Elasticity, Structural Mechanics, Structural Design, Linear Algebra and Applications, Differential Equations and Applications. Many undergraduate and master degree students were supervised in Italy with good success, as well as a few graduate ones, who now are research fellows in Italian universities.
Skills to build up relationships with students is that I recently encouraged the ASI, Engineering Students association in Trento to apply to the EU network BEST, the famous European organization of students in technology; the reaction of ASI was enthusiastic. BEST was funded by many important international industries, with over thirty countries involved and over eighty clubs (right now there are only five partners in Italy).
Academic Year 2008-2009 through present
Solid Mechanics II, BS course for Mechanical and Material Science and Engineering majors, College of Engineering, University of Trento-Italy.
Solid Mechanics and Advanced Structural Engineering II, BS course for Civil Engineering majors, College of Engineering, University of Trento-Italy.
Solid Mechanics and Advanced Structural Engineering, MS course for Building and Architectural Engineering majors (EU program), College of Engineering, University of Trento-Italy.
Academic Year 2007-2008
Solid Mechanics I, BS course for Mechanical and Material Science and Engineering majors, College of Engineering, University of Trento-Italy.
Solid Mechanics II, BS course for Mechanical and Material Science and Engineering majors, College of Engineering, University of Trento-Italy.
Academic Year 2006-2007
Structural Design, BS course for Civil Engineering majors,
Applied Structural Design I and II, courses for Industrial Engineering majors, ,College of Engineering, University of Molise-Italy.
Solid Mechanics II, BS course for Mechanical and Material Science and Engineering majors, College of Engineering, University of Trento-Italy.
Academic Year 2005-2006
Cornell University Summer 2006: TAM310 Advanced Engineering Mathematics;
University of Molise
-Termoli (Civil Eng.): Statics, Theory of Structures, Strength of Materials. -Campobasso (Mechanical Eng.) Strength of Materials.
University of Ferrara (Mechanical Eng. and Material Science) -Basics of Solid and Fracture Mechanics.
Academic Year 2003-2004
Spring Semester 2003-2004 (January-June 2004): Topics in Continuum Mechanics, TAM754: Multiscale Geometry in the Statics and Dynamics of Microstructural Changes. Graduate Program in Theoretical and Applied Mechanics, Cornell University, Ithaca NY -USA.
Selected Theses advised:
-PhD., Galuppi, L.: On the influence of the Laplace pressure on sintered materials: ongoing research. Solid Mechanics Group, Dept. of Mechanical and Structural Engineering, University of Trento (2012).
-PhD: Zurlo, G.: Material and geometric phase transitions in biological membranes, Dissertation for the fulfilment of the Doctorate of Philosophy in Structural Engineering and Continuum Mechanics (Advisors: L. Deseri,
R. Paroni, S. Marzano, Co-Advisor T. J. Healey), University of Pisa, (2008).
- BS thesis about "Measure of the stress intensity factor for ceramic materials suitable for biomedical applications", in collaboration with the Ceramics Center of
ENEA (National Agency of Alternative Energies and Technologies)- Faenza-RA-Italy;
- MS thesis about "Meshless models for the predictions of rate sensitive irreversible large deformation processes in manufacturing".
My experience in this field may be summarized as follows.
-Registered MS Civil and Mechanical Engineer since 1990-Italy
-Consultant part time in structural design at “Studio Giuliani Engineering”, via Chiesa 1, Rovereto (FE) Italy 1990-1996, 1998-2001/2003, 2006-2011
-Co-funder of “Sinapsy Engineering s.a.s.” 1995 (quit in 1997)
-Consultant for “Studio Giuliani Engineering”, 2007-present
-Consultant for SACMI Imola, 2008-2010.
-Consultant for TRW Automotive Italy, 2007-present
-Professional testing of monumental structures (e.g. churches)
-Professional testing of masonry structures, reinforced concrete structures, steel and aluminium structures..
Recent editorial activity
The most recent activity has involved the nomination as Associate Editor of Frontiers in Materials, sect. of Mechanics of Materials, a Nature publisher group (EPFL, Switzerland).
Editorial board member of: Journal of Nanomaterials, International Journal of Medical Nano Research, Journal of Nanomedicine and Applications, Mathematical Problems in Engineering.
Furthermore, service as reviewer is provided for the following journals :
-Biomechanics and Modeling in Mechanobiology,
-Journal of the Mechanics and Physics of Solids,
-Proceedings of the Royal Society-A,
-International Journal of Solids and Structures,
-Communications in Nonlinear Science and Numerical Simulation
-Journal of Nanomechanics and Micromechanics,
-Journal of Elasticity,
-Mathematics and Mechanics of Solids,
-ZAMM- Zeitschrift fuer Angewandte Mathematik und Physik,
-Journal of the European Ceramic Society,
-Physics of fluids,
-Mathematical Models and Methods in Applied Sciences,
-Evolution Equations and Control Theory (EECT).
1. S S Soumya, A. Gupta, A. Cugno L. DESERI, K.Dayal, D. Das, S. Sen, M. Inamdar, Coherent motion of monolayer sheets under confinement and its pathological implications, accepted for publication on PLOS ONE-Computational Biology, arXiv:1507.06481 [q-bio.CB]
2. M. Fraldi, A. Cugno, L. DESERI, K. Dayal and N. Pugno (2015). A frequency-based hypothesis for mechanically targeting healthy and cancer single-cell systems. J. ROYAL SOC.-INTERFACE doi: 10.1098/rsif.2015.0656
3. L. DESERI, P. Pollaci, M. Zingales, K. Dayal (2015) Fractional Hereditariness of Lipid Membranes: Instabilities and Linearized Evolution. J. Mech. Behavior of Biomedical Materials-JMBBM DOI:10.1016/j.jmbbm.2015.09.021
4. DESERI L., Owen D. R. (2015). Stable Disarrangement Phases Arising from Expansion/Contraction or from Simple Shearing of a Model Granular Medium, Int. J. Engineering Sciences doi:10.1016/j.ijengsci.2015.08.001
5. DESERI L., Zingales M. (2015). A mechanical picture of fractional-order Darcy equation., doi:10.1016/j.cnsns.2014.06.021 COMM. NONLINEAR SCIENCE NUM. SIMULATION
6. MM Terzi, K Dayal, L Deseri, M Deserno (2015) Revisiting the Link between Lipid Membrane Elasticity and Microscopic Continuum Models, Biophysical Journal 108 (2), 87a-88a doi: 10.1016/j.bpj.2014.11.510
7. DESERI L., Owen D. R., (2015). Submacroscopic Disarrangements Induce a Unique, Additive and Universal Decomposition of Continuum Fluxes, J. Elasticity doi: 10.1007/s10659-015-9542-5
8. A. Piotrowska, Valentina Piccolo, A. Chiappini, M. Ferrari, M. Pozzi, L. DESERI, D. Zonta (2015) Mechanochromic Photonic Crystals for Structural Health Monitoring, STRUCTURAL HEALTH MONITORING, DEStech Publications Inc. doi: 10.12783/SHM2015/386
9. Finkenauer L., Weissmann J., DESERI L., Majidi C. (2014). Saddle-like Deformation in a Dielectric Elastomer Actuator Embedded with Liquid-Phase Gallium-Indium Electrodes, doi: 10.1063/1.4897551 J APPL PHYSICS 116, 144905 (2014)
10. DESERI L., Gentili G., Golden J. M., (2014). New Insights on Free Energies and Saint-Venant’s Principle in Viscoelasticity, doi: 10.1016/j.ijsolstr.2014.05.031 INT. J. OF SOLIDS AND STRUCTURES
11. DESERI L., Zingales M., Pollaci, P., (2014). The state of Fractional Hereditary Materials (FHM), DIFF. EQN.S AND DYNAMICAL SYSTEMS-DCDS-B DCDS-B 19-7 doi:10.3934/dcdsb.2014.19.2065
12. DESERI L., Owen D. R., (2014) Stable Disarrangement Phases of Elastic Aggregates: a Setting for the Emergence of No-tension Materials with Non-linear Response in Compression, MECCANICA doi::10.1007/s11012-014-0042-7
13. DESERI L., Di Paola M, Zingales M., (2014). Free Energy and States of Fractional-Order Hereditariness, INT. J. OF SOLIDS AND STRUCTURES doi: 10.1016/j.ijsolstr.2014.05.008,
14. Galuppi L., DESERI L., (2014). Combined effects of the interstitial and Laplace pressure in hot isostatic pressing of cylindrical specimens, J. OF THE MECH. MATERIALS AND SOLIDS doi: 10.2140/jomms.2014.9.1
15. DESERI L., Owen D. R.,(2014) Stable Disarrangement Phases of Granular Media I: Classification of the Disarrangement Phases of a Model Aggregate, 14-CNA-005
16. DESERI L., Owen D. R., (2014) Stable Disarrangement Phases of Elastic Aggregates: a Setting for the Emergence of No-tension Materials with Non-linear Response in Compression, 14-CNA-006
17. DESERI L., Zurlo G., (2013). The stretching elasticity of biomembranes determines their line tension and bending rigidity, BIOMECH. MODELING IN MECHANOBIOLOGY-BMMB, DOI: 10.1007/S10237-013-0478-Z.
18. DESERI L., Di Paola M., Zingales M., Pollaci P., (2013). Power-law hereditariness of hierarchical fractal bones, INT. J. NUM. METH. BIOMEDICAL ENG. DOI: 10.1002/cnm.2572
19. Dal Corso, F., DESERI, L., (2013). Residual stresses in random elastic composites: nonlocal micromechanics-based models and first estimates of the representative volume element size, MECCANICA, DOI: 10.1007/s11012-013-9713-z.
20. DESERI L., Pugno N. M., Pollaci P., (2013). Towards understanding adhesion of graphene and lipid layers, PROC. CONF. ON DIAMOND AND CARBON MATERIALS, Elsevier.
21. Lunghi L., DESERI L., (2013). Lock and key mechanism for ligand binding with adrenergic receptors and the arising mechanical effects on the cell membrane, BULL. AMERICAN PHYSICAL SOCIETY 58 (1).
22. DESERI L., Di Paola M., Zingales M., Pollaci P., (2013). Micromechanics-based free energy for Fractional Hereditary Materials (FHM), Proc. XXI AIMETA conf., Torino Sept. 17-20.
23. DESERI L., Owen D. R., (2012). Moving interfaces that separate loose and compact phases of elastic aggregates: a mechanism for drastic reduction or increase in macroscopic deformation, CONTINUUM MECHANICS AND THERMODYNAMICS, DOI:10.1007/s00161-012-0260-y.
24. Bosi F., Mazzocchi E., Jatro I., Dal Corso F., Piccolroaz A., DESERI L., Bigoni D., Cocquio A., Cova M., Odorizzi S., (2012). A collaborative project between Industry and Academia to enhance Engineering Education at graduate and Ph.D level in Ceramic Technology, Accepted for publication on INT.J. ENGINEERING ED.
25. Lunghi L., DESERI L., (2012). Strain gradient membrane effects during cyclic Adenosine Monophosphate Pathway in human trophoblast cells, Proc. IGF conf., ISBN 978-88-95940-37-3.
26. DESERI L., Zurlo G., (2012). 12-CNA-016 Line tension and bending rigidity of biomembranes are determined by their stretching elasticity, Center for Nonlinear Analysis, Carnegie Mellon University, preprints series.
27. DESERI L., Marcari G., Zurlo G., (2012). Thermodynamics, Chapter 5, In: Continuum Mechanics, EOLSS-UNESCO Encyclopedia, G. Saccomandi and J. Merodio Editors. Invited paper.
28. DESERI L., Owen D. R., (2012). Structured deformations and the mechanics of submacroscopically structured solids: perspectives on a new approach, in Nanotechnologies and Smart materials for SHM, Final report of "Nanosense 2011", 61-72, ISBN: 9788888102474.
29. Puntel E., DESERI L., Fried E., (2011). Wrinkling of a Stretched Thin Sheet. J. ELASTICITY, 105 137-170, DOI:10.1007/s10659-010-9290-5.
30. Dal Corso F., DESERI L., (2011). First estimates on the RVE size of random elastic composites with residual stresses, Proc. XX AIMETA conf., Bologna, Sept. 12-15, 2011, ISBN 978-88-906340-1-7.
31. Bigoni D., DESERI L., (2011). Recent Progress in the Mechanics of Defects, Springer ISBN 978-94-007-0313-1.
32. DESERI L., Owen D. R., (2010). Submacroscopically Stable Equilibria of Elastic Bodies Undergoing Disarrangements and Dissipation, MATH. MECHANICS OF SOLIDS, 15 (6) 611-638.
33. DESERI L., Drugan W. J., (2009). An exact micromechanics based nonlocal constitutive equation for random viscoelastic composites, Proc. of the MDP 2007 Conf.
34. Fabbrocino G., Laorenza C., Rainieri C., Santucci De Magistris F., Salzano C., DESERI L., (2009). Seismic monitoring of a retaining wall on piles made of reinforced concrete, XIII ANIDIS 2009 Conference, Bologna.
35. Rainieri C., Fabbrocino G., Santucci de Magistris F., Laorenza C., DESERI L., (2009). Operational Modal Analysis for identification of geotechnical systems, Proc. XIX AIMETA Conf., Ancona.
36. DESERI L., Piccioni M. D., Zurlo G., (2008). Derivation of a new free energy for biological membranes, CONT. MECH. THERMODYNAMICS 20 (5), 255-273.
37. DESERI L., Golden M. J. ( 2007). The Minimum Free Energy for Continuous Spectrum Materials. SIAM J. APPLIED MATH. 67 (3), 869-892.
38. DESERI L., Healey T. J., (2007). Variational derivation for higher gradient Van der Waals fluids equilibria and bifurcating phenomena. NOTE DI MATEMATICA 27, 71-95. Invited paper in recognition of the sixtieth birthday of William Alan Day.
39. DESERI L., Golden M. J., Fabrizio M., (2006). The Concept of a Minimal State in Viscoelasticity: New Free Energies and Applications to PDEs. ARCH. RAT. MECH. ANAL. 181, 43-96.
40. DESERI L. (2004). Crystalline plasticity and structured deformations. In “Multiscale Modeling in Continuum Mechanics and Structured Deformations”, G. Del Piero and D. R. Owen editors, 203-230, Springer New York, Wien.
41. DESERI L., Owen D. R., (2003). Toward a field theory for elastic bodies undergoing disarrangements. JOURNAL OF ELASTICITY 70 (I), 197-236.
42. DESERI L., Owen D. R., (2002). Energetics of Two-level Shears and Hardening of Single Crystals. MATH. MECHANICS OF SOLIDS 7, 113-147.
43. DESERI L., Owen D. R.,. (2002). Invertible Structured Deformations and the Geometry of Multiple Slip in Single Crystals, INTERNATIONAL JOURNAL OF PLASTICITY 18, 833-849
44. DESERI L., Gentili G., Golden M. J., (2002). On the minimal free energy and the Saint-Venant principle in linear viscoelasticity, in Mathematical Models and Methods for Smart Materials, Series on Advances in Math. For Appl. Sciences, World Scientific Publ.
45. DESERI L., Owen D. R., (2000). Active Slip-Band Separation and the Energetics of Slip in Single Crystals. INT. J. PLASTICITY 16, 1411-1418.
46. DESERI L., Mares R., (2000). A Class of Viscoelastoplastic Constitutive Models Based on the Maximum Dissipation Principle. MECHANICS OF MATERIALS 32, 389-403.
47. DESERI L., Bucknall C. B., Rizzieri R., (2000). Variability in the temperature of the secondary loss peak in rubber toughened due to multiple cavitation of the rubber particles, Proc. XI Int. Conf. Deformation Yield and Fracture of Polymers, Cambridge UK
48. DESERI L., Owen D. R., (2000). The critical shear stress in single crystals and structured deformations. Proc. EUROMECH-MECAMAT, Metz, France, 26-29 June.
49. DESERI L., Gentili G., GOLDEN M. J., (1999). An Expression for the Minimal Free Energy in Linear Viscoelasticity. J. ELASTICITY 54, 141-185.
50. Benedetti A., DESERI L., (1999). On a Viscoplastic Shanley-Like Model Under Constant Load, INT. J. SOLIDS AND STRUCTURES 36, 5207-5232.
51. DESERI L., Owen D. R., (1999). A description of the Portevin-Le Chatelier effect in single crystals based on structured deformations, Proc. of Plasticity 99; 31-34 ISBN: 0965946312.
52. DESERI L., Gentili G., Golden M. J., (1999). Minimal free energy for linear viscoelastic solids in the frequency domain, Proc. XIV Aimeta Conf., Como.
53. Benedetti A., DESERI L., (1998). On the behaviour of a viscoelastoplastic Shanley model under constant load, Proc. 2nd Int. Conf. on Mechanics of Time Dependent Materials, Pasadena March1-4.
54. Del Piero G., DESERI L., (1997). On the concepts of state and free energy in linear viscoelasticity. ARCH. RAT. MECH. ANAL. 138, 1-35.
55. Benedetti A., DESERI L., (1997). Generalized displacements evolution for a Shanley bar on viscoelastoplastic hardening soil, 3rd Euromech Solid Mechanics Conf., Stockholm Aug. 18-22.
56. Del Piero G., DESERI L., (1996). On the analytic expression of the free energy in linear viscoelasticity. J. ELASTICITY 43, 247-278.
57. Benedetti A., DESERI L., Tralli A., (1996). Simple and effective equilibrium models for vibration analysis of curved rods, ASCE, J. ENG. MECHANICS 122 (4), 291-299.
58. Del Piero G., DESERI L., (1995). Monotonic, completely monotonic, and exponential relaxation functions in linear viscoelasticity, QUART. APPL. MATH. 53 (2), 273-300.
59. DESERI L., (1995). A priori restrictions on the relaxation function in linear viscoelasticity, dissertation for the fulfilment of the Ph.D. in Solid and Structural Mechanics, Consortium among the universities of Pisa, Florence, Udine, Genova, Bari-Italy.
Submitted manuscripts: in process
Papers to be submitted
60. Dayal K., DESERI L., Lunghi L., Pollaci P., GPCR receptors like to be on lipid rafts.
61. Dayal K., DESERI L., Lunghi L., Pollaci P., Towards modelling membrane effects during cyclic Adenosine Monophosphate Pathway in human trophoblast cells.
Papers in preparation.
62. DESERI L., Zingales M., Pugno N., Micromechanics of the torsional response of hereditary hierarchical solids: the case of bone
63. Cugno A., DESERI L., Fraldi M., Fractional cell response to ultrasound vibrations.
64. DESERI L., Zingales M., Constitutive Model of Hereditary Fluid Mosaic of Lipid
65. Dayal K., DESERI L., Elasticity and peridynamics of thin films.
66. Dayal K., DESERI L., The derivation of electromechanical coupling for flexoelectric membranes.
67. DESERI L., Pugno N. M., Pollaci P., Defects and adhesion of compliant films: the case of soap bubbles.
68. DESERI L., Man C.-S., Paroni R., A probabilistic approach to the plasticity of single crystals accounting for macroscopic non-crystallographic slips.
69. Dal Corso F., DESERI L., Drugan W. J., Zingales M., Viscoelastic random elastic composites: nonlocal micromechanics-based models and estimates of the representative volume element size.
70. DESERI L., Owen D. R., Elasticity of hierarchical bodies predicted with multilevels Structured Deformations.
71. A. Cugno L. DESERI, K.. Dayal, M. Fraldi S S Soumya, A. Gupta, D.. Das, S. Sen, M. Inamdar, New predictions on gastrulation of epithelial cell monolayers
72. DESERI L., Finkenauer L., Majidi C, Weissmann J., Modeling of Curved Cantilever Dielectric Elastomer Actuator Using Universal Solution in Finite Bending.
Description of some selected publications and of the included main results
In this section a selection of papers is presented. In particular, it emerges that very many of the published papers, particularly the ones prior 2012, contain several original results, each of which could have been published separately form the others. This choice has led to fewer, yet qualitatively higher level publications.
DESERI L., and G. Zurlo (2013) In this work, some implications of a recent model for the mechanical behavior of biological membranes (Deseri et al. in Continuum Mech Thermodyn 20(5):255–273, 2008) are exploited by means of a prototypical one-dimensional problem. We show that the knowledge of the membrane stretching elasticity permits to establish a precise connection among surface tension, bending rigidities and line tension during phase transition phenomena. For a specific choice of the stretching energy density, we evaluate these quantities in a membrane with coexistent fluid phases, showing a satisfactory comparison with the available experimental measurements. Finally, we determine the thickness profile inside the boundary layer where the order–disorder transition is observed.
DESERI L., Di Paola M., Zingales M., Pollaci P. (2013), Power-law hereditariness of hierarchical fractal bones, INT. J. NUM. METH. BIOMEDICAL ENG. in press.
In this paper the authors introduce a hierarchic fractal model to describe bone hereditariness. Indeed,
experimental data of stress relaxation or creep functions obtained by compressive/tensile tests have
been proved to be fit by power-law with real exponent 0< b <1. The rheological behavior of the material has therefore been obtained, using the Boltzmann-Volterra superposition principle, in terms of real order integrals and derivatives (fractional-order calculus). It is shown that the power-laws describing creep/relaxation of bone tissue may be obtained introducing a fractal description of bone cross-section and the Hausdorff dimension of the fractal geometry is then related to the exponent of the power-law.
Dal Corso, F. AND DESERI, L., (2013) Residual stresses in random elastic composites: nonlocal micromechanics-based models and first estimates of the representative volume element size, MECCANICA, in press DOI: 10.1007/s11012-013-9713-z
Random elastic composites with residual stresses are examined in this paper with the aim of understanding how the prestress may influence the overall mechanical properties of the composite. A fully non-local effective response is found in perfect analogy with the un-prestressed case examined in (Drugan and Willis, J. Mech. Phys. Solids 44(4):497–524, 1996). The second gradient approximation is considered and the impact of the residual stresses on the estimate of the RVE size is studied whenever the local response is used to describe the mechanical properties of the heterogeneous medium. To this aim, total and incremental formulations are worked out in this paper and the influence of both uniform and spatially varying prestresses are studied.
Among other results, it is shown how rapid oscillations of relatively “small”residual stresses in most cases may result in the impossibility of describing the overall behavior of the composite with a local constitutive equation. On the other hand, prestresses with relatively high amplitudes and slow spatial oscillations may even reduce the RVE.
DESERI L. and Owen, D. R. (2012). Moving interfaces that separate loose and compact phases of elastic aggregates: a mechanism for drastic reduction or increase in macroscopic deformation, CONTINUUM MECHANICS AND THERMODYNAMICS, in press. doi:10.1007/s00161-012-0260-y
This paper encompasses some of the new features of the approach now available to study the mechanics of materials through the field theory of Structured Deformations.
In particular here our attention is devoted to granular materials. For instance s in sand of powdered ceramics the material may be viewed as a continuum composed of much smaller elastic bodies. The multiscale geometry of structured deformations captures the contribution at the macrolevel of the smooth deformation of each small body in the aggregate (deformation without disarrangements) as well as the contribution at the macrolevel of the non-smooth deformations such as slips and separations between the small bodies in the aggregate (deformation due to disarrangements). When the free energy response of the aggregate depends only upon the deformation without disarrangements, is isotropic, and possesses standard growth and semi-convexity properties, we establish (i) the existence of a compact phase in which every small elastic body deforms in the same way as the aggregate and, when the volume change of macroscopic deformation is sufficiently large, (ii) the existence of a loose phase in which every small elastic body expands and rotates to achieve a stress-free state with accompanying disarrangements in the aggregate. We show that a broad class of elastic aggregates can admit moving surfaces that transform material in the compact phase into the loose phase and vice versa and that such transformations entail drastic changes in the level of deformation of transforming material points.
E. Puntel, DESERI L., E. Fried (2011). Wrinkling of a Stretched Thin Sheet. J. Elasticity, 105, 137-170.
This paper represents one of the first analytic studies for the investigation of the occurrence and the development of wrinkling in thin sheets undergoing tension. When a thin rectangular sheet is clamped along two opposing edges and stretched, its inability to accommodate the Poisson contraction near the clamps may lead to the formation of wrinkles with crests and troughs parallel to the axis of stretch. The proposed energy functional includes bending and membranal contributions, the latter depending explicitly on the applied stretch. Motivated by work of Cerda, Ravi-Chandar, and Mahadevan, the functional is minimized subject to a global kinematical constraint on the area of the mid-surface of the sheet. Analysis of a boundary-value problem for the ensuing Euler–Lagrange equation shows that:
-wrinkled solutions exist only above a threshold of the applied stretch, which is actually quite small;
-there exists a sequence of critical values of the applied stretch, which is determined for the first time in the literature, displaying modes with many wrinkles.
The items above predict for the first time the experimental fact that many wrinkles in thin polymeric sheets are observed almost immediately under very small applied stretches.
Although previously proposed scaling relations for the wrinkle wavelength and root-mean-square amplitude are confirmed, in contrast to the scaling relations for the wrinkle wavelength and amplitude, the applied stretch required to induce any number of wrinkles depends on the in-plane aspect ratio of the sheet. When the sheet is significantly longer than it is wide, the critical stretch scales with the fourth power of the length-to-width.
With some efforts the same procedure may be extended to account for:
-viscoelasticity of the membrane, leading to studies of wrinkling relaxation and creep; this may be relevant for corrugated layered composite sensor (e.g. polymeric films alternated with deposited gold, etc.), for which the ridges and troughs must be kept in their original shape and hence relaxation must be limited/prevented;
-biomembranes, for which the evolving elastic/viscoelastic properties of the lipid bilayer may in fact exhibit undesired wrinkling;
as well as other cases and applications.
DESERI L. and Owen, D. R. (2010). Submacroscopically Stable Equilibria of Elastic Bodies Undergoing Disarrangements and Dissipation, MMS, 15 (6) 611-638.
This paper is a step forward towards elucidating the behaviour of continua with microstructure undergoing disarrangements (e.g. slips, voids, micro fractures, etc.) initiated in (8) and continued in (7) (and other papers) within the specific context of the plasticity of metallic single crystals. The new and general field theory for bodies with microstructure provided in (6) sets the basis of all the further developments.
In this framework, the notion of a submacroscopically stable equilibrium configuration of a body and the procedure introduced here for the determination of submacroscopically stable equilibria provide the basis for selecting in a systematic way preferred submacroscopic geometrical states of bodies in equilibrium. The augmented energy underlies this methodology and provides a functional of the macroscopic deformation and the discrepancy (D= G-M) between the deformation gradient without disarrangements and the diffused measure M of such quantities that is stationary for fixed D at equilibrium configurations. This augmented energy is proved not to increase under purely submacroscopic, quasistatic processes in time-independent environments.
These ideas were developed in
Section 3 for arbitrary elastic bodies undergoing disarrangements and dissipation
and were illustrated for specific bodies in Sections 4 and 5. In particular, polymers
and other ductile materials could be described as the bodies studied in
Section 4; the latter have biquadratic free energy response, and their submacroscopically stable equilibria arise only for submacroscopic geometries associated with the spherical
phase, the classical phase, or the prolate phase,
depending upon the value of the ratio
Another class of rheological interesting materials, called here near-sighted fluids, are discussed in Section 5 possess universal spherical and universal prolate phases] that generally are not stress-free, but the submacroscopically stable equilibria that are available to such fluids all are stress-free.
DESERI L., Piccioni M. D.. AND G. Zurlo (2008). Derivation of a new free energy for biological membranes, Continuum Mechanics and Thermodynamics 20 (5), 255-273.
A new free energy for quasi-incompressible and “in-plane fluid” thin biomembranes depending on chemical composition, temperature, degree of order and membranal-bending deformations is derived in this paper for the first time in the literature.
The identification of the membranal contribution to the energy, which is the first order term of it, is done on the basis of a bottom-up approach: this relies upon statistical mechanics calculations. The main result is an expression of the biomembrane free energy density, whose local and non-local counterparts turn out to be weighted by different powers of the reference thickness of the bilayer. The resulting energy exhibits three striking aspects:
(i) the local (purely membranal) energy counterpart turns out to be completely determined through the bottom-up approach mentioned above, which is based on experimentally available information on the nature of the constituents;
(ii) the non-local energy terms, that spontaneously arise from the 3D–2D dimension reduction procedure, account for both bending and non-local membranal effects, the latter being proportional to the magnitude of the gradient of the thinning/thickening measure of strain;
(iii) such terms turn out to be uniquely determined by the knowledge of the membranal energy term, which in essence represents the only needed constitutive information of the model;
(iv) the “line tension” between different phases is recovered through the membrane non-local term, arising in boundary layers between thick and thin zones;
(v) the classical Helfrich model, which neither accounts for chemical composition and temperature nor for the membrane part of the energy (and hence for the switching of phases), is recovered as particular case of the obtained energy.
It is worth noting that the coupling among the fields appearing as independent variables of the model is not heuristically forced, but it is rather consistently delivered through the adopted procedure.
Applications to studies of elastic bifurcations of planar and curved biomembranes may be suitable, as well as extensions to account for the viscoelasticity of liposomes. Studies on bio-inspired nano-strusctured artificial materials may also be pursued by extending the obtained energy.
Applications to more complex biological situations are also under investigations, such as (12).
DESERI L., Golden J. M. (2007). The Minimum Free Energy for Continuous Spectrum Materials. SIAM JOURNAL ON APPLIED MATHEMATICS 67 (3), 869-892.
A general closed expression is given for the isothermal minimum free energy of a linear viscoelastic material with continuous spectrum response.
Two quite distinct approaches are adopted, which give the same final result.
The first involves expressing a positive quantity, closely related to the loss modulus of the material, defined on the frequency domain, as a product of two factors with specified analyticity properties.
The second is the non-trivial generalization of the continuous spectrum version of a method used by Breuer and Onat for materials with relaxation function given by sums of exponentials.
It is further shown that under the assumed properties of the continuum spectrum materials envisaged in this work, minimal energy states, obtained by Del Piero and Deseri (see e.g. ref. (10) of this list) are uniquely related to histories and the work function is the maximum free energy with the property that it is a function of state.
Further developments may be devoted to examine materials with less restrictive properties on its relaxation, such as “power law polymers”, so that the new spectra may determine a non-trivial equivalence class of histories leading to the same minimal state. In such a case the methods (a) and (b) must be revisited for a non-trivial extension.
DESERI L., Golden M. J. AND M. Fabrizio (2006). The Concept of a Minimal State in Viscoelasticity: New Free Energies and Applications to PDEs. Archive for Rational Mechanics and Analysis 181, 43-96.
This is a modern and key work on fundamental aspects of viscoelasticity, which may have practical impacts whenever mechanical components and structures are employed after experiencing unknown and recent past strains. The same issue arises if specimen are subject to treatments resulting in the presence of relaxing pre-stresses.
Indeed, in this paper the impact on the initial-boundary value problem, and on the evolution of viscoelastic systems of the use of a new definition of state based on the stress-response.. Comparisons are made between this new approach and the traditional one, which is based on the identification of histories and states.We shall refer to a stress-response definition of state as the minimal state, introduced by Del Piero and Deseri in 1997.
The energetics of linear viscoelastic materials is revisited and new free energies, expressed in terms of the minimal state descriptor, are derived together with the related dissipations. Furthermore, both the minimum and the maximum free energy are recast in terms of the minimal state variable and the current strain.
The initial-boundary value problem governing the motion of a linear viscoelastic body is re-stated in terms of the minimal state and the velocity field through the principle of virtual power. The advantages are:
-the elimination of the need to know the past-strain history at each point of the body, and
-the fact that initial and boundary data can now be prescribed on a broader space than resulting from the classical approach based on histories.
These advantages are shown to lead to natural results about well-posedness and stability of the motion.
Finally, we show how the evolution of a linear viscoelastic system can be described through a strongly continuous semigroup of (linear) contraction operators on an appropriate Hilbert space. The family of all solutions of the evolutionary system, obtained by varying the initial data in such a space, is shown to have exponentially decaying energy.
Further striking developments are foreseen in the field of Computational Mechanics, because of new and open possibilities of getting new variational principles for viscoelastic mechanical components and structures whenever they are subject to unknown pre-existing strains.
DESERI L., D. R. Owen. (2003). Toward a field theory for elastic bodies undergoing disarrangements. JOURNAL OF ELASTICITY 70 (I), pp. 197-236.
The vast scope of elasticity as a continuum field theory includes the description at the macrolevel of the dynamical evolution of bodies that undergo large deformations, that respond to smooth changes in geometry by storing mechanical energy, and that experience internal dissipation in isothermal motions only during non-smooth macroscopic changes in geometry such as shock waves.
Nevertheless, the needs of bridging closer relationships between the mechanical behaviour at the submacroscopic level and its influence at the macrolevel push forward ideas to deriving multiscale theories, physically-based, which may generalize the classical “one-scale” nonlinear elasticity.
The research described in this paper leads to employing structured deformations of micro/nano-structured continua to obtain a field theory capable of describing such bodies, in the context of dynamics and large isothermal deformations. In other words, an approach owing the evolution of bodies that:
-undergo smooth deformations at the macroscopic length scale, that
-can experience piecewise smooth deformations (disarrangements) at submacroscopic length scales,
-can not only store energy but can also dissipate energy during such multiscale geometrical changes,
is fully worked out in this paper.
The constitutive assumptions employed in this derivation permit the body to store energy
as well as to dissipate energy in smooth dynamical processes. Only one non-classical field G, the deformation without disarrangements, appears in the field equations, and a consistency relation based on a decomposition of the Piola–Kirchhoff stress circumvents the use of additional balance laws or phenomenological evolution laws to restrict G. The field equations are applied to an elastic body whose free energy depends only upon the volume fraction for the structured deformation. Existence is established of two universal phases, a spherical phase and an elongated phase, whose volume fractions are (1 − γ0)3 and (1 − γ0) respectively, with γ0 := (√5 − 1)/2 the “golden mean”.
Applications of such a theory are vitually infinite, as well as specialization to problems of plasticity, damage and other inelastic phenomena involving ductile, as well as granular, materials. Dimensionally reduced theories for beams, plates and shells made of ductile materials undergoing dissipative disarrangements look a fertile and very promising perspective for such an approach.
DESERI L., D.R.Owen. (2002). Energetics of Two-level Shears and Hardening of Single Crystals. MATHEMATICS AND MECHANICS OF SOLIDS 7, 113-147.
With the aim of showing he impact of a new energetic description of the hardening behavior of single crystals undergoing single slip derived by Deseri and Owen (IJP 2000) is analyzed in this work by examining and modelling experiments of Sir. G.I. Taylor and Elam on the distortion of metallic single crystals.
Simultaneous macroscopic simple shear and mesoscopic slips are described by means of a class of structured deformations called ‘‘two-level shears,’’ along with measures of separation of active slip-bands proposed by the authors in (8) and the number of lattice cells traversed during slip. The multiscale energetics of two-level shears deduced in (8) is shown to give rise to a response consistent with the experimentally observed loading and unloading behavior of a single crystal in G. I. Taylor’s soft device, as well as with the Portevin–le Chatelier effect. Such behaviour is predicted through the occurrence of elastic material instabilities at the level of active slip planes.
The manifestation of such phenomenon occurs thanks to the snap-through of the loading point on a stress-strain plot from one stable branch of a constitutive locus, namely a stress-strain plot derived by the energy through simple differentiation, to another one, resulting in jumps of the loading point. The tunnelling of such a point through one or more stable branches of the locus is shown to occur with dissipation. In summary, since such jumps occur at a smaller length scale they predict an irreversible behaviour whenever loading occur beyond a certain stress level and subsequent unloading is considered, actually reproducing the observed plastic response for such crystals. The jagged shape of the curve caused by the mentioned snap-through is consistent with Portevin–le Chatelier effect.
In particular, the initial critical resolved shear stress, the flow stress, and the hardening response are obtained, and an application to aluminium single crystals is displayed.
This paper gives justice to a famous sentence of J. Ericksen who foresaw that plasticity may be explained with elastic material instabilities at a smaller length scale. Henceforth this work puts solid and encouraging bases for a more robust and general nonlinear theory of elasticity for nano/microstructured bodies undergoing disarrangements such as slips, voids, etc.
DESERI L., D. R. Owen. (2000). Active Slip-Band Separation and the Energetics of Slip in Single Crystals. INTERNATIONAL JOURNAL OF PLASTICITY 16, 1411-1418.
This research supports recent efforts to provide an energetic approach to the prediction of stress-strain relations for single crystals undergoing single slip and to give precise formulations of experimentally observed connections between hardening of single crystals and separation of active slip-bands. Non-classical, structured deformations in the form of two-level shears permit the formulation of new measures of the active slip-band separation and of the number of lattice cells traversed during slip.
A new and revealing formula is obtained for the Helmholtz free energy per unit volume as a function of the shear without slip, the shear due to slip, and the relative separation of active slip-bands in a single crystal. This formula is the basis for a model, under preparation by the authors, of hardening of single crystals in single slip that is consistent with the Portevin-Le Chatelier effect and the existence of a critical resolved shear stress.
The approach adopted in this paper may be generalized to more complex kinematical changes of the submacroscopic structure of metallic materials under general states of stress.
DESERI L., R. Mares. (2000). A Class of Viscoelastoplastic Constitutive Models Based on the Maximum Dissipation Principle. MECHANICS OF MATERIALS 32, 389-403.
In this paper, a class of viscoelastoplastic constitutive models, deduced from a thermodynamically consistent formulation is presented. In particular, the exploitation of a penalty version of the maximum dissipation principle leads to a class
of non-linear viscoelastoplastic equations which contains the ones developed by Krempl and Yao (1987) on the one hand, and Haupt and Korzen (1987), Haupt and Lion (1993) among others. Unlike the model discussed in Haupt and Lion (1993), for the class of models derived in this paper the concept of intrinsic time developed by Valanis (1971) is not used.
History and rate dependencies are incorporated through the constitutive model by the concepts of equilibrium stress and overstress, respectively. In the previous sections, it is shown that either in the limiting cases of high viscosity or for extremely slow motions the constitutive model reduces to the one of the equilibrium stress as expected. Further, a numerical analysis of the differential equations describing the viscoelastoplastic behavior in the uniaxial case is investigated. The theoretical predictions obtained in this case turn out to well describe the most important effects of the variation of strain rate for stainless steels, such as abrupt changes during monotonic loading programs, monotonic repeated relaxations, and cyclic loading programs at different strain rates. Applications to the viscoplasticity of metals and the extension of this approach to severe strains may be fruitfully considered.
DESERI L., G. Gentili AND M. J. Golden. (1999). An Expression for the Minimal Free Energy in Linear Viscoelasticity. JOURNAL OF ELASTICITY 54, 141-185.
Dealing with viscoelastic materials, the problem of finding the explicit form of the maximum recoverable work from a given state for all classes of such materials has been an open problem from the late fifties, late sixties. The importance of giving an answer to this question is easily understood if one qualitatively refers to what is a physically the least available energy for the material which is in a given state. Mathematically, this tantamounts to saying that the free energy for the material is not unique and that the minimum possible one has a lot of relevance.
The problem above was only characterized at the beginning of the seventies, although it was not yet solved.
This paper fully provides the sought answer. Indeed., a general expression for the isothermal minimum free energy of a linear viscoelastic material is given in the frequency domain for the full general tensorial case.
The method used here resides on a variational technique. However, the choice of functional to maximize is motivated by showing the equivalence of some alternative definitions of the maximum recoverable work.
Moreover such a maximization in the tensorial case relies crucially on certain results due to Gohberg and Kre˘ın concerning the factorizability of Hermitean matrices.
The resultant expression is shown to be a function of state in the sense of Noll, formulated in the context of linear viscoelasticity by Del Piero and Deseri (1997). Moreover, it turns out to satisfy both the above cited definitions of the free energy.
The paper contains several and fundamental results which could have led to several papers. Nevertheless, they have been collected in this work and will be summarized below.
Detailed, explicit formulae are given for the material responses associated with particular classes of tensorial discrete spectrum models. In Section 3 the constitutive relationship of the material is discussed, together with the concept of state. In Section 4 the maximum recoverable work from a given state is considered in detail. Factorization of a quantity closely related to the tensorial loss modulus is considered in Section 5, which allows the determination of a general expression for the maximum recoverable work in terms of Fourier transformed quantities in Section 6, from a variational argument. A result on the characterization of states in the sense of Noll for viscoelastic materials in the frequency domain is proved in Section 7, with the aid of which the maximum recoverable work is shown to be a function of the state. Since the minimum free energy m is identified with the maximum recoverable work, the results of Sections 6 and 7 refer to m as well. In Section 8, the expression found in Section 6 is shown to have the properties of a free energy according to Graffi’s definition. In Section 9, such an expression is shown to be a free energy in the sense
of Coleman and Owen, by using a suitable norm on the space of the states.
Various choices of norm, including the free energy itself, are compared. Explicit results for particular relaxation functions are presented in Section 10.
Del Piero G., DESERI L. (1997). On the concepts of state and free energy in linear viscoelasticity. ARCHIVE FOR RATIONAL MECHANICS AND ANALYSIS 138, pp. 1-35.
The analysis of the response of viscoelastic solids is a very classical subject and a keystone of Solid Mechanics. As usual, the constitutive law of linear viscoelasticity is the Boltzmann-Volterra equation.
Nevertheless, long term hereditary materials, such as many classes of polymers, are used to make components and structures. Such items are then subject to loading in a time interval of observability, i.e. from a certain time on; very often though the past strain history experienced by each point of the structure is obviously not known. Obvsiouly the latter influences on the overall response of the material, shielding its intrinsic relaxation properties and, in turn, of the structure. The impossibility of knowing past histories suggests that stress relaxation tests with no further loading may reveal if long memory effects are present in the mechanical component under exam. In other words, residual stresses are expected to relax while measured for further and increasing times. Roughly speaking a physical way to detect the effects of past histories would be to characterize such residual stresses.
Henceforth, separating the contributions of the effects of the past history and of the actual loading becomes crucial to predict and verify their overall response.
Henceforth, while using the Boltzmann-Volterra equation, such a separation may then be of great interest.
In this respect, an existing framework introduced by Noll in its context of ‘simple materials’ (roughly speaking materials with local response) helps on going towards that way to treat past and future information. Noll states that ``if two states are dierent . . . then there must be some process which produces different stresses with the two states as initial states''. If we accept this axiom, and if we agree that in our case the processes are the continuations, we may conclude that two histories whose difference produces zero residual stress for all future times must correspond to the same state. If we assume that the current deformation is independent of the past history, then we are led to define a state as a pair whose entries are an equivalence class of histories and a deformation. The deformation is the current deformation, and two histories are equivalent if their difference produce the same residual stress for all times.
With these definitions of process and state, we identify a system (in the sense of the theory of Coleman and Owen), and we use the general results of that theory to study some basic questions of linear viscoelasticity which have long been debated by several authors. One of such question is the character-
ization of the state space. Unlike the usual choice of history-deformation pair there is, however, an important exception, that of the viscoelastic materials of rate type, for which the relaxation function is a linear combination of exponentials. For such materials, a state is usually identified with a finite array of internal variables. Before this paper it was not clear, however, whether this choice is a matter of convenience or is dictated by some sort of general requirements. In the approach that we present here, the possible definitions of a state are strictly limited by the structure of the solution set of equation: Indeed, a state can be represented by a history-deformation pair if and only if the solution set reduces to the null history alone, so that the equivalence classes which constitute the first entry of a state reduce to singletons.
For a relaxation function of exponential type, we show in Section 6 that the finite dimensional characterization of a state is compatible with our defnition, while the characterization as a history-deformation pair is not.
This result can be easily extended to all viscoelastic materials of rate type. We also produce an example of a class of completely monotonic relaxation functions for which the equivalence classes are singletons, and therefore the states are correctly described by history-deformation pairs.
Another question which we consider here is that of the topology of the state space. When a state is defined as a history-deformation pair, it is natural to define the state space as the product of the space of histories and the space of deformations, and to endow it with the product norm of the two spaces. The norm chosen for the space of histories is usually the fading memory norm of Coleman and Noll suggested by the physical consideration that the response of a material with memory is more influenced by the deformations undergone in the recent past than by those that occurred in the far past.
In effect, as shown by the weaker fading memory assumptions made by Volterra, Graffi and Day, a fading memory effect is implicit in the constitutive equation (1.1), provided that the relaxation function decays to its equilibrium value sufficiently fast. The main reason for the success of the approach of Coleman lies in the far-reaching consequences of the principle of the fading memory, which is an assumption of continuity of the constitutive functionals in the topology induced by the fading memory norm. Under this assumption, many general properties of materials with memory have been proved, such as some restrictions and interrelations for the constitutive functionals, and the minimality of the equilibrium free energy in the set of all states having the same current deformation. In this paper, in
the more limited context of linear viscoelasticity, we obtain the same results in a more direct way. We endow the space of histories with a seminorm, which is a norm for the set of the equivalence classes determined by the histories solving the equation obtained by setting the residual stress to zero for all times. The sum of this seminorm and the norm of the space of deformations is a norm for the state space, and we use the topology induced by that norm.
This choice plays an important role in the defnition of the free energy, which is the central subject of the paper. Among the definitions present in the literature, we focus our attention on the defnition given by Coleman and Owen, who define the free energy as a lower potential for the work.
The general results of their theory are then used to prove the existence of a maximal and of a minimal free energy, characterized as the minimum work done to approach a state starting from the natural state, and as the maximum work which can be recovered from a given state, respectively. In the special case of linear viscoelasticity, we found two additional properties beyond those shared by all systems and by all free energies. Namely, we prove that every state can be approached from every other state by a sequence of processes with the property that the sequence of the works done in these processes is convergent, and we prove that the minimal free energy is lower semicontinuous with respect to the topology that we have adopted for the state space.
The last two sections are devoted to the study of two particular classes of viscoelastic material elements, characterized by relaxation functions of exponential type and by completely monotonic relaxation functions, respectively. For the first class, we generalize a result of Graffi and Fabrizio, asserting that there is just one free energy, whose explicit expression was determined by Breuer and Onate. We also show that some other functions, which are usually considered as appropriate to describe the free energy, are indeed not acceptable because they do not define a function of state for this specific class of relaxation functions.