The dynamic behaviour of composites containing long soft fibers of elliptic cross section is studied in the frequency range where the material behaves as a metamaterial. The results of homogenization theory for composites containing soft inclusions are recalled, showing the conditions that lead to a frequency dependent dynamic density coming from the inner resonance of soft inclusions. The dynamic

We review and compare the Born-Huang and the Lemaitre-Maloney theories that lead to analytical expressions for elastic constants, accounting for affine and nonaffine deformations in a lattice (or in a disordered solid). The Born-Huang method is based on Helmholtz free energy while the Lemaitre-Maloney formalism focus on the Gibbs ensemble with the focus on local force. Although starting from different

Dynamic strain aging (DSA) is the process of solute atoms segregating around dislocations on the timescale of loading. Continuum theories of DSA derived from elasticity theory have been shown to severely overpredict both the timescale and strengthening of DSA. Recently, cross-core theory was developed to reconcile this gap, invoking a special single-atomic-hop diffusion mechanism across the core of

The piezoresistive behavior of graphene conductive polymer composites is vital for the performance of smart-sensing materials. In this paper, a numerical method for predicting the piezoresistive properties of graphene rubber composites is established in which user subroutines include the quantum tunneling effect. A representative volume element (RVE) with randomly distributed graphene was constructed

Shales are a class of multiscale, multiphase, hybrid inorganic-organic composite materials exhibiting both frictional and cohesive behavior, and it is very challenging to characterize and interpret their complex mechanical properties. A statistical nanoindentation approach with pertinent viable data analytics was developed to probe the mechanical properties of shales across different length scales

Molecular dynamics (MD) simulations of fused silica glass deforming in pressure-shear, while revealing useful insights into processes unfolding at the atomic level, fail spectacularly in that they grossly overestimate the magnitude of the stresses relative to those observed, e. g., in plate-impact experiments. We interpret this gap as evidence of relaxation mechanisms that operate at mesoscopic lengthscales

Self-healing materials typically can be divided into two types: intrinsic healing that harnesses dynamic bones to autonomously repair fractures, and extrinsic healing that uses the externally added components to enable the bonding of fractured interfaces. Although the theoretical modeling of intrinsic self-healing materials has been recently studied by Wang et al., the fundamental understanding and

Tracking crack propagation at large strains of hyperelastic solids is a challenging task due to the high nonlinearity, nearly incompressibility and ordered tendency in microstructure of the rubbery material under stretch. On the basis of the diffusive crack model, this work presents a new phase-field model by combining the strain energy decomposition and the enhanced assumed strain method. The proposed

Interfacial bond strength is a crucial mechanical property of solid adhesive joints that plays an important role in a wide range of applications. A common way of quantifying mechanical strength of an adhered interface is to measure the apparent adhesion strength by finding the maximum pulling force in a tensile bond test and dividing it by the area. Despite the simplicity of this method, there is growing

We develop a general class of thermodynamically consistent, continuum models based on mixture theory with phase effects that describe the behavior of a mass of multiple interacting constituents. The constituents consist of solid species undergoing large elastic deformations and compressible viscous fluids. The fundamental building blocks framing the mixture theories consist of the mass balance law

Metal-coordination mediated physical hydrogels exhibit high strength/toughness and intriguing mechanical behaviors with the pronounced rate-dependent viscoelasticity and loading-path dependent strain softening. Also, the stress of the reloaded gels increases with more waiting time, indicating a self-healing effect. This paper aims to develop a constitutive model to capture these complex mechanical

Soft materials have experienced an increasing interest from both scientific and industrial communities during the last years. This interest has become even stronger with the potential of such materials to mechanically respond to external stimuli. Among these materials, magneto-active hydrogels (MAHs) offer great opportunities for novel applications, especially within the biomedical field. However,

The interaction between friction and adhesion is a defining factor of the macroscopic behavior of natural and synthetic soft materials. In this work, the interfacial normal and shear adhesion strength of contacts between nanoscale polymer fibers were studied using novel experiments with micromachined devices by which the critical normal and tangential pull-off forces between individual polyacrylonitrile

If a fiber is stretched, abraded on one side, and then gradually relaxed, it will deform into a helix. If the two ends are restrained from rotating during the relaxation, it will form two helical segments of opposite chirality separated by a perversion. Here we investigate the properties of the perversion using a finite-element solution, and show that an excellent approximation to both the shape and

In this paper, we report a new type of bandgap phenomenon called “amplitude-induced bandgap”, which is induced by amplitude in nonlinear metamaterials. Generally, bandgap phenomena in elastic metamaterials or phononic crystals have been achieved by the artificial unit cells which prevent wave propagation with Bragg scattering or internal resonance. However, the amplitude-induced bandgap originates

Metaconcrete is a new type of concrete made of partially replaced locally resonant engineered aggregates for providing enhanced blast and impact resistance. The engineered aggregate consists of solid core coated with a relatively soft material to activate the resonant behaviours of inclusion at the desired frequencies. The resonant aggregates could trigger the negative effective mass density (NEMD)

Epidermal electronic devices (EEDs) have drawn much attention recently due to their wide applications in biological monitoring and biomedicine. Due to the thermo-mechanical coupling between EEDs and skin, skin pain sensation is susceptive to noxious stimuli from EEDs in practical applications. An analytical thermo-mechanical model is developed to predict the temperature and stress distributions in

The equations of dislocation transport at finite crystal deformation were developed, with a special emphasis on a vector density representation of dislocations. A companion thermodynamic analysis yielded a generalized expression for the driving force of dislocations that depend on Mandel (Cauchy) stress in the reference (spatial) configurations and the contribution of the dislocation core energy to

We develop a numerical methodology for the calculation of mode-I R-curves of brittle and elastoplastic lattice materials, and unveil the impact of lattice topology, relative density and constituent material behavior on the toughening response of 2D isotropic lattices. The approach is based on finite element calculations of the J-integral on a single-edge-notch-bend (SENB) specimen, with individual

Thermosetting polymers are hard to be recycled using conventional methods due to their permanently crosslinked networks. It was recently reported that covalent adaptable network (CAN) polymers could be fully decomposed in organic solvents utilizing bond-exchange reactions (BERs). Re-polymerization occurs by heating the decomposed solution to evaporate the solvent. This prominent feature of CANs provides

An elasto-plastic self-consistent (EPSC) polycrystal plasticity formulation is adapted to model deformation of wrought α-uranium (α-U) accommodated by a combination of elasticity, dislocation glide, and deformation twinning. The EPSC model incorporates a strain-path, strain rate, and temperature sensitive dislocation density-based hardening law for the evolution of resistance to slip, twinning, and

Flow of fluids within biological tissues often meets with resistance that causes a rate- and size-dependent material behavior known as poroelasticity. Characterizing poroelasticity can provide insight into a broad range of physiological functions, and is done qualitatively in the clinic by palpation. Indentation has been widely used for characterizing poroelasticity of soft materials, where quantitative

The information richness of imprints topographies obtained after Berkovich nanoindentation tests at grain scale is assessed for identifying all or part of the parameters of a single crystal plasticity law. In a previous paper (Renner et al., 2016), the strong potential of imprints topographies has been shown through a large experimental campaign conducted on nickel samples. A 3D crystal plasticity

A criterion for ductile rupture is derived using Rice’s theory for macroscopic strain localization, and a constitutive relation for porous plastic solids that accounts for inhomogeneous yielding at the mesoscale. At the microscopic scale, it is assumed that failure occurs by void coalescence along a band of voids. An approximate, parameter-free closed form expression for the failure criterion is derived

While metallic glasses (MGs) usually fracture catastrophically under uniaxial loading, external confinement like coating has been proved quite effective for improving the plasticity. The positive effect of confinement was mainly attributed to the lateral confining stress on the interface between sample and confinement, which impedes the excess propagation of shear bands and promotes their multiplication

Computationally efficient methods for bridging length scales, from highly resolved micro/meso-scale models that can explicitly model crack growth, to macro-scale continuum models that are more suitable for modeling large parts, have been of interest to researchers for decades. In this work, an improved brittle damage model is presented for the simulation of dynamic fracture in continuum scale quasi-brittle

We present a thermodynamic description of crystal plasticity. Our formulation is based on the Langer-Bouchbinder-Lookman thermodynamic dislocation theory (TDT), which asserts the fundamental importance of an effective temperature that describes the state of configurational disorder and therefore the dislocation density of the crystalline material. We extend the TDT description from isotropic plasticity

Shape Memory Alloys (SMAs) are a class of materials with unusual properties that have been attributed to the material undergoing a martensitic phase transformation (MPT). Often in β-phase SMAs the austenite is a B2 cubic configuration that transforms into a modulated martensite (MM) phase. First-principles computational results have shown that the minimum energy phase for these materials is not a MM

In situ synchrotron X-ray and neutron diffraction experiments provide a powerful approach to measure lattice strains in bulk polycrystalline materials. They are being increasingly used for quantitative characterization of microscale deformation within and between grains and phases. Here we use a self-consistent micromechanics model to obtain a general analytic solution of the grain-level lattice strains

This paper is concerned with the optimality of the variational bounds of the Hashin-Shtrikman type (VHS) for nonlinear composites, first obtained by Ponte Castañeda (1991a) by means of the corresponding HS bounds for suitably optimized linear comparison composites (LCCs). For simplicity, this problem is addressed in the context of porous viscoplastic materials with incompressible, isotropic matrix

When a point force travels in a solid with a speed greater than the velocity of the elastic wave induced, the interfering elastic wave fronts will form a Mach cone. This phenomenon is called the elastic Cherenkov effect (ECE). In this study, the ECE in soft matter was investigated with emphasis on backward Mach cone formation. Phase diagrams were proposed based on the theoretical analysis to elucidate

We consider a body, homogeneous or periodic, equipped with a structure composed of dynamic inhomogeneities uniformly distributed along a line, and study free and forced sinusoidal waves (Floquet - Bloch waves for the discrete system) in such a system. With no assumption concerning the wave nature, we show that if the structure reduces the phase velocity, the wave localizes exponentially at the structure

Comminution is the process of grainsize reduction due to grain crushing, which is common in both natural and industrial problems that involve brittle granular media. Grain crushing is a stochastic process, where the strength of individual grains is determined both by their own size and mineralogy, and the local arrangement of their neighbouring particles, here termed grainsize fabric. The relationship

We study wetting of an elastic membrane whose surface can resist stretch by surface stress. Through energy minimization, we obtain the general equilibrium equations and a configurational energy balance equation at the contact line, i.e., the Young equation, modified for an elastic membrane. We use a 3D large deformation formulation with general elastic constitutive behavior for the membrane and its

Sharks and rays have distinctive skeletons among vertebrate animals, consisting primarily of unmineralized cartilage wrapped in a surface tessellation of minute polygonal tiles called tesserae, linked by unmineralized collagenous fibers. The discrete combination of hard and soft tissues is hypothesized to enhance the mechanical performance of tessellated cartilage (which performs many of the same functional

Based on the micromorphic theory, a novel mathematical formulation for the mechanical modeling of material growth and remodeling processes in finite deformation is developed. These two processes have an important significance in evolution of living tissues. The presented formulation incorporates both the volumetric growth and mass flux phenomena into the modeling with the aid of the micromorphic theory’s

This paper presents a unified cohesive zone formulation for describing the fatigue-driven crack onset and propagation in quasi-brittle materials. This approach is based on formulating a modified traction-displacement law involving linear softening, which accounts for the onset of fatigue failure described by materials S-N curves. The fatigue crack propagation in a steady-state regime is described as

The classic nonlinear fracture problem of a fully yielded, mixed mode stationary crack in a power law hardening material for conditions of plane stress under small-scale yielding is reconsidered. It has been determined that two different asymptotic solutions are required to represent the full range of mixed mode loading. Neither asymptotic solution has the double root of the linear elastic counterpart

The mechanics of biological entities, from single molecules to the whole organ, has been extensively analyzed during the last decades. At the smaller scales, statistical mechanics has fostered successful physical models of proteins and molecules, which have been later incorporated within constitutive models of rubber-like materials and biological tissues. At the macroscopic scale, the additive decomposition

Recent years have witnessed a surging growth in developing anisotropic hydrogels. Particularly, a new type of microfiber-based anisotropic hydrogel has emerged by transforming nature's existing anisotropic soft materials into hydrogels. For example, wood-based hydrogels feature crosslinked networks serving as the matrix with stiffer micro-sized cellulose bundles as the reinforcement. These anisotropic

Like all other materials, biological soft tissues are subject to general laws of physics, including those governing mechanical equilibrium and stability. In addition, however, these tissues are able to respond actively to changes in their mechanical and chemical environment. There is, therefore, a pressing need to understand such processes theoretically. In this paper, we present a new rate-based constrained

The concepts of open, cellular substrates for stretchable electronic systems are of interest partly due to their ability to minimize disruptions to the natural diffusive or convective flow of bio-fluids in advanced, bio-integrated implants. The overall elastic properties, and in particular the stretchability, of such systems are difficult to determine, however, because they depend strongly on the alignment

Dynamic networks are found in a majority of natural materials, but also in engineering materials, such as entangled polymers and physically cross-linked gels. Owing to their transient bond dynamics, these networks display a rich class of behaviors, from elasticity, rheology, self-healing, or growth. Although classical theories in rheology and mechanics have enabled us to characterize these materials

Micro-electromechanical systems (MEMS) that rely on structural vibrations have many important applications, ranging from oscillators and actuators, to energy harvesters and vehicles for measurement of mechanical properties. Conventional MEMS, however, mostly utilize two-dimensional (2D) vibrational modes, thereby imposing certain limitations that are not present in 3D designs (e.g., multi-directional

Development of advanced synthetic materials that can mimic the mechanical properties of non-mineralized soft biological materials has important implications in a wide range of technologies. Hierarchical lattice materials constructed with horseshoe microstructures belong to this class of bio-inspired synthetic materials, where the mechanical responses can be tailored to match the nonlinear J-shaped

Estimates of the effective stiffness of a composite containing multiple types of inclusions are needed for the design and study of functionally graded systems in engineering and physiology. While excellent estimates and tight bounds exist for composite systems containing specific classes and distributions of identical inclusions, these are not easily generalized to complex systems with multiple types

We argue in favor of representing living cells as automata and review demonstrations that autonomous cells can form patterns by responding to local variations in the strain fields that arise from their individual or collective motions. An autonomous cell's response to strain stimuli is assumed to be effected by internally-generated, internally-powered forces, which generally move the cell in directions

An inverse method is presented for estimating shear stress in the work material in the region of chip-tool contact along the rake face of the tool during orthogonal machining. The method is motivated by a model of heat generation in the chip, which is based on a two-zone contact model for friction along the rake face, and an estimate of the steady-state flow of heat into the cutting tool. Given an

Random fiber networks are assemblies of elastic elements connected in random configurations. They are used as models for a broad range of fibrous materials including biopolymer gels and synthetic nonwovens. Although the mechanics of networks made from the same type of fibers has been studied extensively, the behavior of composite systems of fibers with different properties has received less attention

Proteins operate and interact with partners by dynamically exchanging between functional substates of a conformational ensemble on a rugged free energy landscape. Understanding how these substates are linked by coordinated, collective motions requires exploring a high-dimensional space, which remains a tremendous challenge. While molecular dynamics simulations can provide atomically detailed insight

Excitation-contraction coupling is the physiological process of converting an electrical stimulus into a mechanical response. In muscle, the electrical stimulus is an action potential and the mechanical response is active contraction. The classical Hill model characterizes muscle contraction though one contractile element, activated by electrical excitation, and two non-linear springs, one in series

Convolutions are a classical hallmark of most mammalian brains. Brain surface morphology is often associated with intelligence and closely correlated to neurological dysfunction. Yet, we know surprisingly little about the underlying mechanisms of cortical folding. Here we identify the role of the key anatomic players during the folding process: cortical thickness, stiffness, and growth. To establish

Despite their seemingly delicate appearance, thin biological membranes fulfill various crucial roles in the human body and can sustain substantial mechanical loads. Unlike engineering structures, biological membranes are able to grow and adapt to changes in their mechanical environment. Finite element modeling of biological growth holds the potential to better understand the interplay of membrane form

Understanding the difference between ex vivo and in vivo measurements is critical to interpret the load carrying mechanisms of living biological systems. For the past four decades, the ex vivo stiffness of thin biological membranes has been characterized using uniaxial and biaxial tests with remarkably consistent stiffness parameters, even across different species. Recently, the in vivo stiffness was

Many biological systems are coated by thin films for protection, selective absorption, or transmembrane transport. A typical example is the mucous membrane covering the airways, the esophagus, and the intestine. Biological surfaces typically display a distinct mechanical behavior from the bulk; in particular, they may grow at different rates. Growth, morphological instabilities, and buckling of biological