Abstract not available

When a crack interacts with material heterogeneities, its front distorts and adopts complex tortuous configurations that are reminiscent of the energy barriers encountered during crack propagation. As such, the study of crack front deformations is key to rationalize the effective failure properties of micro-structured solids and interfaces. Yet, the impact of a localized dissipation in a finite region

Void nucleation on grain boundary (GB) has been regarded as an important mechanism of damage initiation in ductile polycrystalline materials under dynamic loading. The high tensile stress induced by this loading mode enables interface incompatibility (i.e. the incompatibility of mechanical properties across the GB) to significantly affect intergranular spall damage initiation. In the present work,

Crystalline materials can be strengthened by introducing dissimilar phases that impede dislocation glide. At the same time, the changes in microstructure and chemistry usually make the materials less ductile. One way to circumvent the strength-ductility dilemma is to take advantage of heterogeneous nanophases which simultaneously serve as dislocation barriers and sources. Owing to their superior mechanical

Anisotropy in the mechanical response of materials with microstructure is common and yet is difficult to assess and model. To construct accurate response models given only stress–strain data, we employ classical representation theory, novel neural network layers, and L1 regularization. The proposed tensor-basis neural network can discover both the type and orientation of the anisotropy and provide

Creep fracture mechanics has been extensively studied in the past half a century, but the gap between the creep crack-tip asymptotic field and crack growth prediction has not been effectively bridged so far, hindering the development of high temperature damage tolerance design. Here a predicting model is developed for three-dimensional crack growth in power-law creeping solids with the C(t)PC-Tz asymptotic

This paper investigates issues that have arisen in experimental and theoretical studies of the stability of a dielectric elastomeric layer bonded to a stiff substrate and subject to a voltage difference across the top and bottom conducting surfaces of the layer. The role of equi-biaxial pre-stretch of the layer prior to bonding to the substrate is a central factor in the investigation. The focus is

Short fatigue crack growth across grain boundaries of differing tilt and twist combinations has been investigated in three dimensions using coupled crystal plasticity and extended finite element methods. Crack path selection and growth rate are mechanistically determined by considering crystallographic planes containing the highest shear strain and the achievement of a critical stored energy density

Martensite/ferrite (M/F) interface damage largely controls failure of dual-phase (DP) steels. In order to predict the failure and assess the ductility of DP steels, accurate models for the M/F interfacial zones are needed. Several M/F interface models have been proposed in the literature, which however do not incorporate the underlying microphysics. It has been recently suggested that (lath) martensite

Recent experimental and computational studies at different scales reveal an apparent flow-induced anisotropy of the inelastic deformation behaviour in metallic glasses (MGs). However, the anisotropic damage behaviour accompanied by the formation of shear bands is not adequately described in the previous constitutive modelling work. In this study, we develop a thermodynamically-consistent, anisotropic

When a polymer network is stretched, some polymer strands do not bear loads. Examples include looped strands, dangling strands, and extremely long strands. When the polymer network is submerged in a solvent, however, all strands mix with solvent molecules. This distinction between strands that bear loads and strands that do not leads us to modify the Flory-Rehner model. The modified model has three

Biodegradable synthetic hydrogels have emerged as promising materials for tissue engineering and drug/cell delivery applications. However, their successful implementation requires precise understanding of the degradation response in terms of mechanical properties, swelling, and mass loss. In this work, we develop a thermodynamically-consistent continuum framework and constitutive models for coupled

Recently there has been an increase in demand for soft and biocompatible electronic devices capable of withstanding large stretch. Ionically conductive polymers present a promising class of soft materials for these emerging applications due to their ability to realize charge transport across the polymer network, while preserving the desired mechanical and chemical features. As opposed to electron transfer

Mechanical couplings such as axial–shear and axial–bending have great potential in the design of active mechanical metamaterials with directional control of input and output loads in sensors and actuators. However, the current ad hoc design of mechanical coupling without theoretical support of elasticity cannot provide design guidelines for mechanical coupling with lattice geometries. Moreover, the

Mass transport phenomenon in concrete structures is strongly coupled with their mechanical behavior. The first coupling fabric is the Biot’s theory according to which fluid pressure interacts with solid stress state and volumetric deformation rate of the solid induces changes in fluid pressure. Another coupling mechanism emerges with cracks which serve as channels for the fluid to flow through them

Ultrasonic powder compaction is a rapid low-temperature consolidation technique that can fully densify metal powders in several seconds. Current understanding of the process is derived from qualitative interpretations of relative density measurements and postmortem analyses of compacts. Here, we elucidate the underlying densification mechanisms using in situ measurements of the instantaneous stress

Cellular aggregates play a significant role in the evolution of biological systems such as tumor growth, tissue spreading, wound healing, and biofilm formation. Analysis of such biological systems, in principle, includes examining the interplay of cell–cell interactions together with the cell–matrix interaction. These two interaction types mainly drive the dynamics of cellular aggregates which is intrinsically

When a hydrogel deforms, the water molecules inside the hydrogel move together with the polymer network. At a particular time scale and length scale, the water migration within the hydrogel as well as the water exchange with the environment can greatly affect the deformation of the hydrogel. In this work, we study the rate-dependent fracture of hydrogels due to water migration both experimentally and

The rupture of hydrogels and swellable elastomers involves large deformations, and there exists a large literature devoted to their experimental characterization including methods for measuring and enhancing fracture toughness. Analytical investigations of the fracture of hydrogels have recognized the importance of large deformations and the contributions of liquid flow, but they have largely been

The vast majority of our current knowledge regarding the basic mechanisms controlling irradiation effect on mechanical properties is based almost entirely on the results of post-irradiation experiments or theoretical models. However, the concurrent effects of irradiation, mechanical stress, and thermal damage on the failure phenomena of materials and components remain largely unexplored due to its

In this paper, we present a unit cell showing a band-gap in the lower acoustic domain. The corresponding metamaterial is made up of a periodic arrangement of one unit cell. We rigorously show that the relaxed micromorphic model can be used for metamaterials’ design at large scales as soon as sufficiently large specimens are considered. We manufacture the metamaterial via metal etching procedures applied

We consider the influence of elasticity and anisotropic surface energy on the energy-minimizing shape of a two-dimensional void under biaxial loading. In particular, we consider void shapes with corners for which the strain energy density is singular at the corner. The elasticity problem is formulated as a boundary integral equation using complex potentials. By incorporating the asymptotic behavior

Deformable nanoparticles (DNPs) such as liposomes are widely used to load and deliver drugs across hydrogel-like biological barriers such as mucus and tumor interstitial matrix. The rigidity of DNPs is found to have a huge effect on their diffusivity in biological gels, while the underlying mechanism is still unclear. Here, we propose a theoretical model to describe the diffusion behavior of DNPs in

Phase-field models are a leading approach for realistic fracture problems. They treat the crack as a second phase and use gradient terms to smear out the crack faces, enabling the use of standard numerical methods for simulations. This regularization causes cracks to occupy a finite volume in the reference, and leads to the inability to appropriately model the closing or contacting – without healing

Although it is known that biological materials have remarkable fracture strength and toughness, the underlying mechanisms have not been fully understood. A key question is what effects of the structural arrangement of the microstructure are in biological materials. To address this problem, we developed a fracture model based on the fundamental solutions of the crack and rigid line inclusions in matrix

We present a mechanistic theory for predicting void evolution in the Li metal electrode during the charge and discharge of all-solid-state battery cells. A phase field formulation is developed to model vacancy annihilation and nucleation, and to enable the tracking of the void-Li metal interface. This is coupled with a viscoplastic description of Li deformation, to capture creep effects, and a mass

This work provides analytical estimates for the macroscopic elastic, viscous and viscoplastic response of composite materials with particulate microstructures consisting of various families of ellipsoidal inclusions with given properties, volume fractions, shapes and orientations that are randomly distributed with ‘ellipsoidal symmetry’ in a matrix of a different material. The estimates follow from

The mechanical properties of nacre (mother-of-pearl), which are superior to those of its constituent materials, derive from a micro-architecture formed by the arrangement into parallel laminae of individual aragonite tiles with surface asperities, bonded by organic interlayers. A mechanical model is developed to determine how the contact profile that defines the geometry of the tile surface affects

This work develops a dynamic linear homogenization approach in the context of periodic metamaterials. By using approximations of the dispersion relation that are amenable to inversion to real-space and real-time, it finds an approximate macroscopic homogenized equation with constant coefficients posed in space and time; however, the resulting homogenized equation is higher order in space and time.

Elastomeric membranes are flexible and stretchable, commonly found in soft devices, soft robotics, and flexible electronics. The indentation of free-standing elastomeric membranes induces large transverse deflection, leading to the puncture of elastomeric membranes. In this paper, we study the indentation and puncture of elastomeric membranes by sphere-tipped indenters. Effects of the indenter tip

Living cells are a complex soft material with fascinating mechanical properties. Confusingly, experiments have shown that cells exhibit stiffening and more solid-like behaviors under uniaxial stretches or shear, while they present softening and more fluid-like behaviors under biaxial stretches. For both of these seemingly paradoxical stiffening and softening rheological behaviors, cells often exhibit

This work undertakes the analysis of continuous media that carry simultaneously two different material or geometric structures in the same material substrate. Even when these two structures are individually perfectly uniform and homogeneous, their combination may result in a non-uniform assembly. Thus, in contradistinction to the classical interpretation of material defectivity as a manifestation of

Slip along a frictional contact between elastic bodies can be stable or unstable, leading to stick-slip motion. Frictional slip can also be associated with vibrations. The condition for these vibrations and their characteristics remains poorly understood. To address this issue, which is relevant to engineering and earth science, we carry out a linear stability analysis of a spring-and-slider system

Cellular uptake of nanoparticle (NP) is an important biological process involving mechanically and structurally heterogeneous environments, such as biophysical heterogeneity of single extracellular vesicles and biomechanical heterogeneity of small viral capsids. Despite of these heterogeneous environments, poor understanding of membrane interacting with vesicle NP of non-uniform mechanical properties

Motivated by a simplified model for atomic structures, and based on the concept of objective structures in R3, we introduce a type of subsets of Rn that we call locally translation-isometric sets (LTI sets). These sets are defined by the property that the ɛ-neighborhoods around every point in them are isometric copies of each other. For n=3, in the case ɛ=∞ they are simply objective structures and

Titins are mainly responsible for passive mechanical properties of a single muscle fiber, which, however, can be compromised by the change in molecular structures of titins occurring in some muscle-related diseases. Based on molecular structures of titins within a sarcomere unit, we have developed a constitutive theory for the passive elasticity of a single muscle fiber with the utilization of the

The two bonding mechanisms for the elements of the Periodic Table are defined. These are for the standard bond stretching effect and for a newly recognized and developed bond bending-bond shearing effect. This work involves the interpretation, definition and utilization for the bond bending-bond shearing function at the atomic bonding scale. Section 2 provides the relevant information. The solids forming

Gels are comprised of polymer networks swelled by some interstitial solvent. They are under wide investigation by material scientists and engineers for their broad applicability in fields ranging from adhesives to tissue engineering. Gels’ mechanical properties greatly influence their efficacy in such applications and are largely dictated by their underlying microstructures and constituent-scale properties

In this contribution, we propose a novel continuum mechanical concept to determine the homogenised mechanical response of random fibre networks. Their free energy is calculated as an average of the fibre free energy over the distribution of stretch, which forms the core of the new theory. The fibre-scale kinematic information contained in this distribution is intrinsic to the model and available for

The ductile failure of crystalline materials is strongly linked to the growth of intragranular voids. The estimation of the overall yield criterion thus requires to take into account the anisotropic plastic behavior of the single crystal. In the framework of the kinematic limit-analysis approach, this problem has been considered up to now with Gurson-type isotropic trial velocity fields. In the present

Motivated by experiments on dendritic actin networks exhibiting surface growth, we address the problem of the stability of this growth process. We choose as a simple, reference geometry a biaxially stressed half-space growing at its boundary. The actin network is modeled as a neo-Hookean material. A kinetic relation between growth velocity and a stress-dependent driving force for growth is utilized

Grain boundary processes such as shear coupling and sliding are a consequence of plastic distortion accompanying grain boundary motion. Atomic scale studies using molecular dynamics (MD) and phase field crystal simulations demonstrate non-unique and stress-dependent shear coupling, a key feature that recently motivated the introduction of disconnections as the primary carriers of grain boundary plasticity

Twisted bilayer materials have attracted tremendous attention due to their unique and novel properties. In this work, we derive a thermodynamic model for twisted bilayer graphene (tBLG) within the framework of the classical statistical mechanics. The effect of interlayer twist is introduced by the Moiré-dependent out-of-plane deformation, based on which the twist associated Helmholtz free energy is

In this paper, a multiscale rationale is applied to develop a bottom-up modelling strategy for analysing the elasto-damage response of osteons, resulting in a first step towards a refined mechanical description of cortical bone tissue at the macroscale. Main structural features over multiple length scales are encompassed. A single osteon is described by considering a multi-layered arrangement of cylindrical

The long-standing problem of arbitrarily-shaped discrete dislocation loops in three-dimensional heterogeneous material structures is addressed by introducing novel singularity-free elastic field solutions as well as developing adaptive finite element computations for dislocation dynamics simulations. The first framework uses the Stroh formalism in combination with the biperiodic Fourier-transform and

We present a phase field-based electro-chemo-mechanical formulation for modelling mechanics-enhanced corrosion and hydrogen-assisted cracking in elastic–plastic solids. A multi-phase-field approach is used to present, for the first time, a general framework for stress corrosion cracking, incorporating both anodic dissolution and hydrogen embrittlement mechanisms. We numerically implement our theory

Tuning the electronic properties through phase engineering of two-dimensional transition metal dichalcogenides (TMDCs) is promising for their applications in electronic devices, energy conversion, and so on. Here, we establish a phase-field continuum mechanics model that accounts for both the finite deformation and mechanically induced phase transition of monolayer molybdenum disulfide (MoS2) and molybdenum

The purpose of this work is the development and determination of higher-order continuum-like kinematic measures which characterize discrete kinematic data obtained from experimental measurement (e.g., digital image correlation) or kinematic results from discrete modeling and simulation (e.g., molecular statics, molecular dynamics, or quantum DFT). From a continuum point of view, such data or results

We introduce a dislocation density tensor and derive its kinematic evolution law from a phase field description of crystal deformations in three dimensions. The phase field crystal (PFC) model is used to define the lattice distortion, including topological singularities, and the associated configurational stresses. We derive an exact expression for the velocity of dislocation line determined by the

We begin the article by summarizing some key developments in the field of Peridynamics (PD) and arrive at a conclusion that two schools of PD are emerging in recent years. One school takes a more traditional view of PD as a model of a nonlocal continuum, while another approaches PD as a discretization methodology for local continua where the nonlocality is reduced under mesh refinement. Adhering to

In this work, we construct an effective continuum model for architected sheets that are composed of bulky tiles connected by slender elastic joints. Due to their mesostructure, these sheets feature quasi-mechanisms — low-energy local kinematic modes that are strongly favored over other deformations. In sheets with non-uniform mesostructure, kinematic incompatibilities arise between neighboring regions

Strain localization is often a precursor to the ductile failure of materials. This paper investigates plastic strain localization phenomena in the case of random microstructures, namely cubic cells made of an elastic-perfectly plastic matrix embedding distribution of identical non-overlapping spherical voids. The consideration of random microstructures allows for a better representation of the interaction

Frictional aging is observed at a wide range of length- and time-scales, and plays a crucial role in functioning of micro- and nanomachines, as well as in the nucleation and recurrence of earthquakes. Here, we developed an analytical model for description of frictional aging mediated by dynamical formation and rupture of microscopic interfacial contacts. The model accounts for the presence of various

In spite of many potential applications due to their superior mechanical properties, magnesium alloys still find many practical restrictions primarily due to our limited knowledge of their failure mechanisms. In situ and non-destructive strain measurements on the microstructural scales are critical in understanding the fatigue crack behavior, which has greater advantages than the macroscopic measurements

Materials indented at small scales may simultaneously exhibit indentation size and strain rate effects which complicate the identification of the mechanisms that control deformation and strength. Here, we explore the possibility that indentation size and rate effects in some materials can be decoupled in a simple way. Nanoindentation tests with various load-time histories were carried out to measure

This work investigates internal damage by void growth in NT microstructures via crystal plasticity. The framework incorporates length-scale effects and explicitly models twin boundary migration. Using finite-deformation, plane strain finite element calculations of porous unit cells, we analyze the roles of twin size, plastic anisotropy and twin boundary migration on void evolution over a range of controlled