Plenary Speakers
Robert O. Ritchie
Distinguished Professor of Mechanical Engineering
Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Materials Science & Engineering, University of California Berkeley, California, USA
Title: Damage Tolerance of High-Entropy Alloys: Conflict between the Toughness of BCC vs. FCC Alloys
Damage Tolerance of High-Entropy Alloys: Conflict between the Toughness of BCC vs. FCC Alloys
Robert O. Ritchie
Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Materials Science & Engineering, University of California Berkeley, California, USA
ABSTRACT
A material's ability to undergo limited deformation is critical to conferring toughness, as it enables the dissipation of high stresses that would otherwise cause fracture. Indeed, resistance to fracture is a compromise - a combination of two, often mutually exclusive, properties of strength and deformability. It can also be considered as a mutual competition between intrinsic damage processes that operate ahead of a crack tip to promote its advance and extrinsic crack-tip shielding mechanisms that act at, or behind, the tip to locally diminish crack-tip stresses and strains. In this context, we examine the damage-tolerant properties of multiple principal-element alloys, commonly known as high-entropy alloys (HEAs). Single-phase face-centred cubic (FCC) HEAs, notably CoCrNi-based, appear to be the toughest on record (KIc ~ 450-550 MPa√m), with strength, ductility, and toughness all enhanced at cryogenic temperatures. This phenomenon appears to be related to prolonged strain hardening induced by a regulated sequence of plasticity mechanisms, catalyzed by local short-range order. In contrast, BCC refractory alloys (RHEAs), such as NbTaMoW, display high strengths at ultrahigh temperatures, but invariably in compression, as they are brittle in tension due to high ductile-to-brittle transition temperatures (DBTTs), often far exceeding 1000°C (KIc < 10 MPa√m). To address this, we examined RHEAs containing group-IV elements, specifically a NbTaTiHf alloy, which shows no apparent DBTT, with KIc values exceeding 250 MPa√m at room temperature and ~90-100 MPa√m at 20K. This excellent toughness is again associated with a series of plasticity mechanisms but, distinct from FCC HEAs, now in a competitive sequence that does not induce much strain hardening and involves unusual mechanisms, such as kink-banding. These group-IV element-containing alloys still do not have quite the strength of brittle RHEAs, but if this can be solved, they potentially represent a superior class of refractory alloys for extreme ultrahigh-temperature environments.
Biography: Rob Ritchie is the H.T. & Jessie Chua Distinguished Professor of Engineering in the Mechanical Engineering Department and Professor in the Materials Science and Engineering Department at the University of California, Berkeley. He is also a Faculty Senior Scientist at the Lawrence Berkeley National Laboratory. He holds M.A., PhD, and Sc.D. degrees in physics/materials science from Cambridge University. Prof. Ritchie is known for his research on the fracture and fatigue of a broad range of engineering materials, including metals, ceramics, and composites; biological materials, such as skin, teeth, and bone; and other natural materials such as bamboo and fish scales. His current interests, though, are focused on the damage tolerance of high-entropy metallic alloys, which is the topic of his talk. His work has been widely cited, with over 129,000 citations and an h-index of 169 (on Google Scholar). He is a Fellow of the Royal Society and of the Royal Academy of Engineering in the U.K., the National Academy of Sciences and the National Academy of Engineering in the U.S., the Russian Academy of Sciences, the Royal Swedish Academy of Engineering Sciences, and the Academy of Athens.
Zhigang Suo
Allen E. and Marilyn M. Puckett Professor of Mechanics and Materials
School of Engineering and Applied Sciences, Harvard
University, Cambridge, MA 02138, USA
Developing polymer networks for strength and toughness
Developing polymer networks for strength and toughness
Zhigang Suo
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
ABSTRACT
The aspiration for sustainability, as well as functions, has been driving recent advances in the development of polymers. This talk focuses on how to elevate the strength of polymer networks through topology and chemistry. A covalent polymer network is orders of magnitude weaker than individual covalent bonds. The weakness comes not from individual covalent bonds, but from the topology of the network and the noncovalent chemistry between polymer strands. Before a polymer network ruptures, only a minute fraction of covalent bonds in the network bear high tension. The network forms and breaks high-tension paths. Each path consists of a sequence of crosslinked strands from one end of the network to the other. The paths localize tension in that they are sparse, and the strands off the paths remain coiled and bear low tension. This talk describes several examples in which we design and synthesize polymer networks that delocalize tension and amplify strength. Also described is the principle of flaw-tolerant recycling of waste tires.
Biography: Zhigang Suo is the Allen E. and Marilyn M. Puckett Professor of Mechanics and Materials at Harvard University. He earned a bachelor’s degree in Engineering Mechanics from Xi’an Jiaotong University in 1985 and a Ph.D. in Engineering Science from Harvard University in 1989.
After completing his doctorate, Suo joined the faculty of the University of California, Santa Barbara, where he established a research group focused on the mechanics of materials and structures. In 1997, he moved to Princeton University and subsequently joined Harvard University in 2003.
Prof. Suo teaches courses in solid mechanics and applied mathematics, while his research explores the mechanical behavior of materials and structures. His work examines fundamental processes such as fracture, deformation, polarization, and diffusion, driven by thermodynamic forces including stress, electric fields, electron wind, and chemical potential. His research has important applications in microelectronics, large-area electronics, soft and active materials, and lithium-ion batteries. Through his research and teaching, he has made significant contributions to the understanding and development of mechanics of materials and structures.
According to Google Scholar, as of August 2026, he has received 107290 citations and has an h-index of 168, reflecting the significant impact and influence of his scholarly work.
Laura De Lorenzis
Professor of Computational Mechanics
Department of Mechanical and Process Engineering, ETH Zürich, Switzerland
Title: Variational phase-field modeling of fracture – where we are and what’s next
Variational phase-field modeling of fracture – where we are and what’s next
Laura De Lorenzis
Department of Mechanical and Process Engineering, ETH Zürich, Switzerland
ABSTRACT
Variational phase-field models of brittle fracture have profoundly changed the computational landscape of fracture mechanics. Rooted in the variational formulation of Griffith’s theory, they represent cracks by an additional smooth field, letting nucleation, propagation, branching and merging of cracks with arbitrarily complex topologies emerge from the minimization of a single energy functional, without ad hoc criteria or explicit crack tracking. However, as approximations of Griffith’s theory—which does not incorporate a strength criterion—these models lack flexibility in prescribing material-specific strength surfaces and thus struggle to accurately capture crack nucleation under multiaxial stress states.
To overcome this limitation, we recently proposed a variational phase-field model that approximates cohesive fracture and accommodates an arbitrary (convex) strength surface, independently of the regularization length scale. The formulation leads to sharp cohesive cracks and naturally enforces a sharp non-interpenetration condition; it satisfies strain hardening for a sufficiently small ratio of the regularization length to the material’s cohesive length, whereas stress softening and “crack-like” residual stresses are fulfilled by construction. First- and second-order stability results are established in one and three dimensions.
The lecture reviews this framework and recent advancements. On the modelling side, we discuss the pros and cons of different strength criteria and compare our analytical results with numerical experiments. On the computational side, local eigenstrain solutions use closed-form or one-dimensional iterative approaches, enabling straightforward extension of brittle phase-field codes. An extension to dynamics enables the study of the interaction of elastic waves with pre-existing cracks and of dynamic crack propagation. Throughout, we assess the predictive capabilities of the framework through comparisons with experimental results. We conclude with open problems and promising directions for future research.
Biography: Laura De Lorenzis is Professor of Computational Mechanics at ETH Zürich, Switzerland, where she has been based since 2020 in the Department of Mechanical and Process Engineering. She began her academic career in Italy and, in 2013, moved to TU Braunschweig, Germany, as Professor and Director of the Institute of Applied Mechanics. She was also a founding member and the first Chair of the Center for Mechanics, Uncertainty and Simulation in Engineering.
Professor De Lorenzis has held visiting positions at several internationally renowned institutions, including Chalmers University of Technology, the Hong Kong Polytechnic University, Massachusetts Institute of Technology, where she was a Fulbright Fellow in 2006, Leibniz University Hannover, where she held an Alexander von Humboldt Fellowship in 2010–2011, the University of Texas at Austin, and the University of Cape Town.
Her research focuses on computational and applied mechanics, with major contributions to advanced numerical methods and the modelling of complex mechanical phenomena. Her distinctions include the RILEM L’Hermite Medal, AIMETA Junior Prize, IIFC Young Investigator Award, Euromech Solid Mechanics Fellowship, IACM Fellowship, and the IACM Oden Computational Mechanics Award 2026. She has also received two best paper awards and two student teaching prizes, as well as an ERC Starting Grant in 2011.
Professor De Lorenzis has delivered more than 30 plenary lectures and authored or co-authored over 170 journal papers. Since 2023, she has served as Editor of Computer Methods in Applied Mechanics and Engineering. Her work has received over 22,220 citations and an h-index of 76, highlighting her international impact in computational mechanics.
Emmanuel Gdoutos
Full Member of the Academy of Athens, Greece
Academy of Athens, Athens, Greece
Title: Failure of Sandwich Structures
Failure of Sandwich Structures
Emmanuel Gdoutos
Academy of Athens, Athens, Greece
ABSTRACT
Sandwich structures consisting of strong and stiff facings and lightweight cores offer improved stiffness and strength-to-weight ratios compared to monolithic materials. Under flexural loading, the facings carry almost all of the bending, while the core takes the shear loading and helps to stabilize the facings. Facing materials include metals and fibre-reinforced composites. The latter are being used in advanced applications due to the large strength-to-weight ratio. The core materials mainly include honeycombs, foams and wood.
Possible failure modes of sandwich structures include tensile or compressive failure of the facings, debonding at the core/facing interface, indentation failure under concentrated loads, shear core failure, wrinkling of the compression face and global buckling.
A thorough investigation of the failure mechanisms of composite sandwich beams under four- and three-point bending and cantilever beams was undertaken. The beams were made of unidirectional carbon/epoxy (AS4/3501-6) facings and a PVC closed-cell foam (Divinycell) core. Two types of core materials, H100 and H250 with densities 100 and 250 kg/m3, respectively, were used. Sandwich beams were loaded under bending moment, and shear and failure mechanisms were observed and compared with analytical predictions. The failure mechanisms investigated are core failure, facing wrinkling, facing debonding and indentation failure. The various mechanisms have been studied separately, and both initiation and ultimate failure have been determined. Initiation of a particular failure mechanism and triggering and interaction with other failure mechanisms were also investigated. The initiation of the various failure mechanisms depends on the material properties of the constituents (facings, adhesive, core), geometric dimensions and type of loading. Failure mechanisms were discussed according to the type of loading applied.
Biography: Emmanuel Gdoutos is a Full Member of the Academy of Athens, Greece, where he holds the chair of Theoretical and Experimental Mechanics. He is an internationally distinguished scholar in mechanics, with major contributions to elasticity, fracture mechanics, experimental mechanics, composite materials, and nanotechnology.
Professor Gdoutos is a member or fellow of numerous prestigious academies and scientific organisations worldwide, including the European Academy of Sciences and Arts, European Academy of Sciences, Academia Europaea, International Academy of Engineering, American Academy of Mechanics, and American Association for the Advancement of Science. He is also a Foreign Member of the Russian, Bulgarian, and Ukrainian Academies of Sciences and has received honorary doctorates from several universities and academic institutions in Greece and abroad.
He has served as President of major international scientific organizations, including the Society for Experimental Mechanics, European Structural Integrity Society, European Society for Experimental Mechanics, and International Congress on Fracture. He has also led prominent Greek scientific and cultural institutions, including the Hellenic Society of Linguistic Heritage and the Theocaris Foundation of the Academy of Athens.
Professor Gdoutos has authored more than 130 journal papers, over 180 conference papers, nine books in Greek, six books in English, and edited 24 books. His research spans elasticity, singularity problems, fracture mechanics, optical experimental methods, composite and sandwich structures, and nanocomposites. His achievements have earned numerous honors, including a 2015 special issue of Meccanica, honorary citizenship of Lesvos, and over 7,300 citations with an h-index of 36.
His outstanding contributions have earned him numerous awards and distinctions. In 2015, the journal Meccanica devoted a special issue to his work. He is also an honorary citizen of Lesvos, Greece. His scholarly impact is reflected in more than 7,300 citations and an h-index of 36, according to Google Scholar.
Paul Steinmann
Professor at Friedrich-Alexander-Universität
Institute of Applied Mechanics, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
Title: Crickey, it’s cracking! Secrets and joy of the mechanics and fracture of soft matter
Crickey, it’s cracking!
Secrets and joy of the mechanics and fracture of soft matter
Paul Steinmann1 and SoftFrac Team2
1. Institute of Applied Mechanics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
Glasgow Computational Engineering Centre, Glasgow University, Glasgow, UK
2. ERC Advanced Grant Project “SoftFrac”, www.softfrac.research.fau.eu
Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
ABSTRACT
The mechanics and fracture of soft matter present formidable hurdles for experimentalists, theoreticians, and computational scientists alike. Indeed, the mechanical response of soft materials is dictated by intricate geometric and physical non-linearities. These characteristics become increasingly complex when accounting for multi-physical couplings with non-mechanical fields driven by electrical, magnetic, chemical, thermal, or photonic stimuli. Collectively, these interactions frequently give rise to highly counter-intuitive phenomena in the material's macroscopic behaviour. From an experimental perspective, probing the mechanical response of soft matter - ranging from ultra-soft elastomers with stiffnesses on the order of a few kilopascals to biological tissues such as the human brain, which exhibits a modulus well below the kilopascal threshold - while simultaneously accounting for non-mechanical fields, introduces severe laboratory constraints. These challenges translate directly to the theoretical domain, where modellers must deploy either molecular dynamics, continuum mechanics, or multi-scale formulations to successfully capture deformation and failure. Within the continuum framework, both constitutive formulation and capturing the fracture process - encompassing crack initiation and propagation - remain formidable, mathematically rigorous problems. To address these issues, experimental data can be leveraged to inform data-driven constitutive models, while the discrete fracture process can be resolved using advanced numerical strategies, spanning variational phase-field fracture approaches to explicit formulations reliant on sophisticated remeshing algorithms, both coming with their own intricacies. In this presentation, I shall outline our recent advancements across the interconnected domains sketched above, achieved under the auspices of the European Research Council (ERC) Advanced Grant project "SoftFrac"
Biography: Paul Steinmann is Full Professor at Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany, where he has been active since 2007. He completed his Doctorate in Engineering in 1992, obtained his Venia Legendi in Mechanics in 1996, and was appointed Full Professor at the University of Kaiserslautern in 1997. Since 2017, he has also served as Co-Director of the Glasgow Computational Engineering Centre at the University of Glasgow, UK.
Professor Steinmann is an internationally recognised scholar in computational and continuum mechanics, with research spanning material modelling, multi-scale methods, multi-physics, non-standard continua, configurational mechanics, failure and fracture mechanics, biomechanics, and advanced finite element and discretisation methods. His research has received major international recognition, including two ERC Advanced Investigator Grants (2011 and 2022) and the Royal Society Wolfson Research Merit Award (2017). He was elected Fellow of the International Association for Computational Mechanics (IACM) and EUROMECH in 2006 and received the Timoshenko Visiting Scholar Award at Stanford University in 2007.
He has authored four research monographs and edited two major volumes on configurational mechanics, in addition to publishing extensively in international peer-reviewed journals. As of August 2026, his work has received 28,116 citations and an h-index of 83 according to Google Scholar.
Professor Steinmann has held numerous editorial and leadership positions, including Editor-in-Chief of GAMM-Mitteilungen from 2005 to 2016. He has contributed to major scientific selection panels, international mechanics organisations, conferences, and research programmes, and has delivered numerous plenary, keynote, and invited lectures. His academic leadership includes directing major DFG Collaborative Research Centres, Research Training Groups, and Research Units.
Chun H. Wang
Scientia Professor at the University of New South Wales
School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Australia
Title: Multiscale Fracture Mechanics and Design of Multi-Phase Fibre-Reinforced Composites for Extreme Environments
Multiscale Fracture Mechanics and Design of Multi-Phase Fibre-Reinforced Composites for Extreme Environments
Chun H. Wang
School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Australia
ABSTRACT
Incorporating low-dimensional nanostructures into polymer matrices offers a promising strategy for enhancing fibre-reinforced composites in extreme thermal, mechanical, and electrochemical environments. Rigid nanomaterials can significantly improve the fracture resistance of brittle polymer matrices, including under cryogenic conditions where the matrix becomes highly brittle. However, the mechanisms governing nanoscale toughening and their translation to composite laminate behaviour remain poorly understood. Predictive modelling is further challenged by the large separation of length scales, from nanoscale particle–matrix interactions to microscale matrix cracking and macroscale composite failure. This presentation reports recent developments in a multiscale fracture-mechanics framework for quantifying and exploiting nanomaterial toughening in fibre-reinforced composites under extreme thermal environments. At the nanoscale, a
representative unit-cell model is used to investigate the effects of nanoparticle surface properties, size, and volume fraction, revealing optimum particle sizes and volume fractions for maximising fracture resistance. These mechanisms are then upscaled to the microscale through a micromechanical model capable of predicting traction–separation relationships under mixed-mode loading. The approach substantially reduces the number of matrix-dominated fracture properties requiring experimental characterisation, from 15 to four. The resulting constitutive relationships are incorporated into a continuum damage framework to predict delamination and ply-splitting failure under coupled thermal–mechanical loading.
The presentation will also examine emerging approaches to predictive modelling of structural energy-storage composites. The integration of nanoparticle-toughened structural electrolytes and electrodes can enable composites that simultaneously carry mechanical loads and store electrical energy; however, their design remains largely empirical. Extending the multiscale fracture-mechanics framework to a multiphysics framework that captures coupled electrochemical–mechanical behaviour, including the effects of cyclic ion transport on mechanical properties and fracture behaviour, enables the shift away from empirical materials modification towards predictive materials-by-design, accelerating the rational design of multi-phase composites that combine mechanical performance with energy-storage functionality.
Biography: Chun-hui Wang is a Scientia Professor in the School of Mechanical and Manufacturing Engineering at the University of New South Wales (UNSW), Sydney, Australia. His research focuses on multifunctional fibre-reinforced composites for extreme-environment applications, including nanotoughened carbon fibre composites for cryogenic liquid storage, composite repairs, multiaxial fatigue, and fracture mechanics.
His scientific publications have received over 30,000 citations, with an H-index of 92 (Google Scholar). He is an elected Fellow of the Australian Academy of Technological Science and Engineering (FTSE), recognising his seminal contributions to engineering science and the translation of advanced engineering technologies into practical applications, including commercial products, design software, and engineering standards.
