One of the major challenges in computational mechanics of materials remains to bridge the length-scale and time-scale gaps between the computational and experimental methods to study the microstructure of materials. Traditional molecular dynamics is a powerful tool at the nanoscale, but it does not allow to simulate such mechanical experiments as AFM microscopy dealing with sub-micrometric lengths

In this paper we present a fully nonlinear stick-and-spring model for graphene subjected to in-plane deformations. The constitutive behaviors of sticks and springs are defined, respectively, by the modified Morse potential and a nonlinear bond angle potential. The equilibrium equations of the representative cell are written considering large displacements of the nodes (atoms) and the stability of the

Shape memory polymers (SMPs) are a class of soft active materials that have the ability to retain one or multiple temporary shapes and exhibit deformation as a response to stimuli. The temporary shapes involved can be very complex but SMPs can recover large amounts of strains as compared to other smart materials. They have a wide range of applications in fields as diverse as healthcare, transportation

The extreme out-of-plane flexibility makes membranes vulnerable of wrinkling, which limits the applications with stringent-accuracy demands and high-frequency requirements. In this study, a theoretical analysis is proposed to predict the minimum of min-principal stress min(σmin), representing the wrinkling capability of the stretched membrane with an arbitrary aspect ratio and random curved edges,

Computational multiscale methods for analyzing and deriving constitutive responses have been used as a tool in engineering problems because of their ability to combine information at different length scales. However, their application in a nonlinear framework can be limited by high computational costs, numerical difficulties, and/or inaccuracies. In this paper, a hybrid methodology is presented which

Deep cryogenic treatment (DCT) has been known since the 1930s to improve hardness, fatigue resistance, and wear resistance of steel. While the effect of DCT on wear properties has been well documented, there is no consensus regarding the causal mechanisms, nor a widely accepted quantitative description of them. DCT transforms retained austenite into martensite and triggers the precipitation of fine

Atherosclerosis is one of the most dangerous forms of Cardiovascular disease (CVD) due to its asymptomatic nature during its early stages of development. The carotid sinus is a favorable location for plaque progression because of the temporal disturbances experienced in its environment. By performing a transient Fluid-Structure Interaction (FSI) on a healthy idealized carotid artery, zones of low Wall

The mechanism of the effect of stresses on wave propagation in a fluid-saturated porous media has not been well understood. The goal of this paper is to fill this gap. First we formulated the general equations of motion in a homogeneously pre-stressed fluid-saturated medium and use them to derive explicit expressions of velocity dependence on stresses. Equations for fast and slow longitudinal waves

An inhomogeneity embedded in a continuum medium is a classical problem in solids that dates back to Maxwell, and the fields within an ellipsoidal inhomogeneity governed by temperature-independent constitutive law are well known to be uniform, rendering them important applications in composite analysis. The thermoelastic problem of an inhomogeneity in temperature-dependent medium, on the other hand

It is well-known by now that the Hashin–Shtrikman bounds imply that the two-point correlation functions are not in general sufficient to estimate accurately the response of composites, especially when their underlying phases exhibit infinite contrast, e.g., porous materials. Starting from this longstanding, albeit qualitative result, this work investigates quantitatively the relevance of using two-point

In this paper, transient surface Green's functions (GFs) excited by a general dynamic pulse buried in a constrained transversely isotropic (TI) half-space are derived in analytical forms. The constrained transverse isotropy is defined by an explicit relation that expresses one of the five elastic constants in terms of the other four independent constants so that no coupled P-SV wave exists. Use is

In this research, it has been tried to study the mechanical behavior of a micro annular circular sheet made of microcrystalline cellulose material. A new combination between the modified higher-order shear deformation, also, quasi-three-dimensional displacement fields and the modified couple stress theory has been presented for simulating the mentioned micro-sheet under the transverse loading. Consequently

Flexoelectricity is an interesting electromechanical coupling that exists in all dielectrics when the deformation is inhomogeneous. The intensity of flexoelectricity is highly related to the deformation gradient and the dimensions of dielectric structures. Although flexoelectricity plays a significant role in micro-/nano- devices' behaviors, the complexity of electromechanical coupling impedes the

Magneto-active polymers are polymer-based composites consisting of magnetizable micro-particles embedded in an elastomeric matrix material. The presence of magnetic particles provides strong tunability to the stiffness and damping properties of the polymeric composites under the magnetic field. We propose here a novel free energy-based phenomenological modeling for magneto-active polymers. Coupled

We develop a viscoelastic generalization of the elastic Eshelby inclusion solution, where the inclusion and surrounding matrix are two different viscoelastic solids and the inclusion’s eigenstrain is a time-periodic oscillatory input. The solution exploits the Correspondence Principle of Linear Viscoelasticity and a Discrete Fourier Transform to efficiently capture the steady-state oscillatory behavior

A model for the mechanics of a hyperelastic material reinforced with unidirectional and bidirectional fibers is presented in finite plane elastostatics. This includes the refinement/development of a series of continuum-based prediction models to accommodate the nonlinear responses of both the matrix material and the reinforcing fibers. The kinematics of the embedded fibers, including the torsional

One of the assumptions of Linear Elastic Fracture Mechanics is that the crack faces are traction-free or, at most, loaded by bounded tractions. The standard Irwin’s crack closure integral, widely used for the computation of the Energy Release Rate, also relies upon this assumption. However, there are practical situations where the load acting on the crack boundaries is singular. This is the case, for

A homogeneous conductive medium containing random sets of identical spherical inclusions is considered. The self-consistent effective medium method is used for solution of the homogenization problem and calculation of the effective thermal conductivity parameters of the composite. For time-varying fields, the effective conductivity parameters are non-local operators with respect to time. The effective

Transverse wrinkles usually emerge in a uniaxially stretched elastic film and can be suppressed upon further tension, which is an instability-restabilization behavior due to the nonlinear competition between stretching energy and bending energy. Here, we show that curvature can effectively and precisely tune the wrinkling localization and amplitude. To quantitatively explore curvature effect on the

The necessity of the inclusion of the second invariant of the left Cauchy-Green deformation tensor B, namely I2, in the strain energy function W of rubber-like materials is analysed. Universal relationships that underline such necessity are revisited, and experimental data are examined to establish the trends in the variation of ∂W/∂I2. Corroborated by the established experimental trends, we consider

This paper examines the axisymmetric problem of a penny-shaped crack located in a poroelastic halfspace that is modelled by Biot poroelasticity. The paper first examines the axisymmetric problem of the mechanics of fluid injection over a circular area within a halfspace that would create the skeletal stress state necessary to initiate fracture. The triggering of the fracture is assumed to create an

In this paper, we investigate the formation of two-dimensional surface wrinkles in a pre-deformed compressible soft electroactive (SEA) plate. Two common electrical loading protocols are considered: one is the so-called voltage-control where the plate is applied with a constant voltage across the thickness; the other is named as charge-control where the plate is activated by uniformly spraying electrical

This work investigates the void surface effects on the macroscopic yield criterion of ductile materials embedded with nanosized spherical cavities. The solid matrix is treated as an isotropic, von Mises, incompressible and rigid-perfectly plastic material. Based on the trial velocity field proposed by Gurson and the first-order Taylor approximations of the equivalent volume strain rate, surface strain

Recent experiments have shown that grain size of metals in graphene/metal nanocomposites has a significant effect on their strength and ductility. As the grain size decreases, the strength tends to increase while the ductility tends to decrease. But quantitative assessment of these observations remains a challenge. In this paper, we establish a hierarchical scheme from nano to macro scale to evaluate

The spherical particle composite with the microstructure varying from perfectly ordered to completely disordered is considered. The partially disordered periodic packings of spheres are generated in the framework of the reprehensive unit cell model with aid of the Metropolis algorithm. The orientation order invariants Qi introduced by Steinhardt et al. [Phys. Rev. B 28 (1983) 784] in the molecular

An asymptotic model for time-harmonic motion in fully-coupled linear thermoelastic orthorhombic materials is presented. The asymptotic approach takes advantage of the observation that the parameter expressing departure from the purely adiabatic regime is extremely small in practice. Consequently, the leading order bulk response turns out to be non-dissipative, and is governed by the usual equations

In the current investigation, a novel mathematical formulation is established for the size-dependent thin doubly curved microshells of revolution with arbitrary meridian curve based on the modified couple stress theory and the Kirchhoff-Love's hypothesis. The impact of size-dependency on both the governing equations and reduced boundary conditions is taken into account. Afterwards, based on the weak

Data fitting and interconversion remain to be a difficult task in linear viscoelasticity. On the basis of transfer function, a generalized fractional model is proposed to fit linear viscoelastic data. The new model is modified from the fractional Maxwell model, and it is abbreviated as the MFM model in this paper. Common fractional viscoelastic models, including the fractional Kelvin and fractional

Recently, multiscale modeling frameworks combining micromechanics-based homogenization methods and atomistic simulations have been widely applied to predict the effective stiffness of particulate-reinforced composites. Although most studies demonstrated that theoretical predictions incorporating interfacial damage are necessary to explain atomistic simulation results, the microscopic origin of the

Pores, vugs, and cracks configurations affect physical and mechanical properties of porous and fractured (PF) media, specifically the percolations of pores/vugs/cracks trigger the dramatic change of conductive-like properties such as thermal conductivity, diffusivity, elastic modulus of PF media. It has been a key but unresolved issue how to accurately capture the percolation thresholds of these complex

In this paper, we derive the second-order crack opening displacement tensor for an arbitrarily oriented elliptical crack in an elliptically orthotropic (EO) matrix. This result is obtained in explicit closed form. The approach is based on the Saint-Venant’s idea of linear transformation between boundary value problems for elliptically orthotropic and isotropic bodies. The solution utilizes the classical

The increasing applications of nanoporous materials in engineering structures call for robust strength criteria that are able to model the size effects of multiscale voids inherent to these materials. Many literature works have devoted to this line of research by either employing the classical homogenization approach or extending Gurson’s model to incorporate the nanovoid surface mechanics. However

This work provides a comparative analysis of the effect of nanovoids distribution associated with trigonometric functions on forced mechanical characteristics of functionally graded curved nanobeams. A geometrically exact model is developed for the simply-supported beam utilizing a higher-order beam theory including thickness stretching effect. In order to capture the small-scale effects, the governing

The extremely low thickness-to-length ratio (aspect ratio) of graphene nanofillers has long been considered beneficial to the overall thermal conductivity of graphene-polymer nanocomposites as it creates large surface area and extra channels for phonon transport. From time to time, however, a lower aspect ratio of the nanofillers did not yield a higher thermal conductivity as expected. To explain such

This paper derives a novel analytical model for stress dependent permeability of argillaceous porous media (APM) considering clay swelling using fractal theory. The model shows that the stress dependent permeability is a function of effective stress, clay content, clay expansion coefficient, initial irreducible water saturation and rock lithology. It is validated by the available test data from experimental

Size-dependent dynamic responses of small-size frames are modelled by stress-driven nonlocal elasticity and assessed by a consistent finite-element methodology. Starting from uncoupled axial and bending differential equations, the exact dynamic stiffness matrix of a two-node stress-driven nonlocal beam element is evaluated in a closed form. The relevant global dynamic stiffness matrix of an arbitrarily-shaped

The paper is focused on the dynamic homogenization of lattice-like materials with lumped mass at the nodes to obtain energetically consistent models providing accurate descriptions of the acoustic behavior of the discrete system. The equation of motion of the Lagrangian one-dimensional lattice is transformed according to a unitary approach aimed to identify equivalent non-local continuum models of

A thermodynamic framework has been developed for a class of amorphous polymers used in fused deposition modeling (FDM), in order to predict the residual stresses and the accompanying distortion of the geometry of the printed part (warping). When a polymeric melt is cooled, the inhomogeneous distribution of temperature causes spatially varying volumetric shrinkage resulting in the generation of residual

Recently, among other smart and multifunctional materials, magneto-electric soft materials are expected to open a new horizon with myriad of potential applications such as wireless energy harvesting, spintronics and nonvolatile memories, magneto-electric random access memory, to mention a few. Magneto-electric coupling can be defined as the ability of a material to electrically polarize upon the application

A weakly nonlinear analysis is conducted for localized necking of a hyperelastic solid cylinder under axial stretching based on the exact theory of nonlinear elasticity. The amplitude equation derived is shown to be consistent with the one-dimensional model recently proposed by Audoly and Hutchinson (J. Mech. Phys. Solids 97, 2016, 68–91). It is shown that results based on the infinite-length approximation

This paper investigates the Mode-I crack problem that a three-dimensional infinite space of transversely isotropic multi-ferroic composite medium is weakened by multiple coplanar penny-shaped cracks under uniform mechanical, electric and magnetic loadings. These cracks are arbitrarily distributed in an isotropic plane of the material. Four kinds of idealized electro-magnetic crack boundary conditions

This work provides comparative analysis of the effect of manufacturing processes and process parameters on mechanical and thermal properties of stainless steel 316L. The properties are compared for the parts produced by additive manufacturing (Selected Laser Melting), thermal spraying, casting, hot/cold rolling, hot-isostatic pressing, and forging technologies. Each of these manufacturing processes

We discuss the propagation of localized surface waves in the framework of the linear Gurtin–Murdoch surface elasticity and taking into account a roughness of a free boundary. We derive a boundary-value problem for anti-plane motions with curvilinear boundary and surface stresses. Using the asymptotic technique developed earlier, we obtain the form of a localized wave and analyze its amplitude evolution

The resonance phenomenon is for the first time investigated in anisotropic and functionally graded anisotropic nano-size structure. The structure is considered as a doubly curved shell which is modeled exploiting a quasi-three-dimensional model and nonlocal strain gradient theory in order to predict the small-size effects. The doubly-curved nanoshell is made from aragonite with an orthorhombic crystal

It is developed and derived that the ductile/brittle transition is located at ν*=2/3 where ν*is the renormalized form of the standard Poisson's ratio. This is for homogeneous and isotropic materials in the state of uniaxial tension. This then converts to the ductile/brittle transition as being established at μ/k =1/2 where μ and k are the shear and bulk moduli. The consequences of these results for

Three-dimensional exact solutions for temperature and thermoelastic stresses in multilayered anisotropic plates are derived for advanced boundary-value problems with general boundary conditions. The extended Stroh formalism is formulated to include the thermal coupling with the Eringen nonlocal elasticity theory that captures small scale effects. The simply supported structures are subjected to time-harmonic

In this paper, we derive an exact closed-form solution of three-dimensional transient Green's functions (GFs) at the free surface of a constrained transversely isotropic (TI) half-space due to an arbitrarily oriented surface point force of Heaviside time variation. The solution clearly delineates the distinct features of body waves (P-, SV- and SH- waves) as well as Rayleigh surface wave in displacement

We analyse a problem of a hydraulic fracture driven by a non-Newtonian shear-thinning fluid. Fluid viscosity is described by the four-parameter truncated power-law model. By varying the parameters of the rheological model we investigate spatial and temporal evolution of fluid flow inside the crack and the resulting fracture geometry. A detailed quantitative and qualitative analysis of the underlying

A homogeneous anisotropic conductive medium with a set of anisotropic heterogeneities of arbitrary shapes is considered. Calculation of local fields in the medium subjected to arbitrary external fields is reduced to systems of volume integral equations. For numerical solution, these equations are discretized using Gaussian approximating functions concentrated at the nodes of a regular grid. The elements

The current article presents a thorough investigation into the natural frequencies and mode shapes of thin doubly curved shallow microshells by taking into account the influence of material length scale parameter. The mathematical model of system is obtained by applying the Hamilton's principle along with the modified couple stress theory and the Kirchhoff-Love's shell theory. In order to extract the

A new methodology of the evaluation of the thermal/electrical properties of the skeleton of a porous material from measurements of the overall properties of this material saturated with various conductive fluids is proposed and numerically verified. The approach is based on the concept of equivalent microstructure and solution of the inverse homogenization problem in the framework of Mori-Tanaka-Benveniste

A nonlocal theory is presented for the bending in large deformations under applied loads of an initially straight rod. This has similarities with the classical Euler’s elastica in the sense that the bending stiffness remains homogeneously constant, but it depends on an integral average of the entire curvature field. The discretized form of the equilibrium equations is identical to those governing the

Several recent experiments have shown that the glass-transition temperature and temperature-dependent storage modulus of graphene-polymer nanocomposites are dependent on the graphene loading, but at present no theory exists to explain these observations. In this paper, we take the view that both issues are closely tied to the principle of irreversible thermodynamics, and that, by considering the phase

The effective piezoelectric properties of heterogeneous materials are evaluated in the context of periodic homogenization, whereby a variational formulation is developed, articulated with the extended Hill macrohomogeneity condition. The entire set of homogenized piezoelectric moduli is obtained as the volumetric averages of the microscopic properties of the individual constituents weighted by the

A new mechanical and analytical models of the human eye is presented in order to study Glaucoma disease and its complications. Mechanical modeling of the human eye is performed with a hollow sphere under internal pressure. The first-order shear deformation theory is used to obtain the governing equations of the model, which are the set of partial differential equations. The nonlinear von Kármán assumption

We investigate the microscopic and long-wave (or macroscopic) instabilities in fiber composites (FCs) with hyperelastic phases. To study the influence of the phase stiffening behavior, we employ the phase constitutive models that are developed based on the non-Gaussian statistics of polymeric molecular chains. These non-Gaussian models accurately predict the non-linear behavior of soft materials. Moreover

The thickness-extensional mode in layered piezoelectric plates can be inevitably interfered by some undesirable eigen-modes due to the lateral edge effect. A reported theoretical method to predict high-frequency coupled vibrations is the 2D high-order plate theory derived based on approximate dispersion relations. In this paper, based on accurate dispersion relations a novel approach called Frequency

By using the variational-asymptotic method, a universal asymptotic model for composite sandwich plates is established to achieve a great compromise between efficiency and accuracy through the synthesis of two competing theories: equivalent single-layer theories and layer-wise theories. When each layer of a sandwich structure can be individually considered as an elastic plate, and all material constitutive

Payne effect is the complex nonlinear response of filled elastomers to oscillatory loading. Although usually characterized by the decrease in the storage modulus with strain amplitude, and by the bell-shaped curve of loss modulus with strain amplitude, the response has many other peculiar features. The manner of decrease in storage modulus with strain amplitude does not change when the frequency of