The higher-order unified gradient elasticity theory is conceived in a mixed variational framework based on suitable functional space of kinetic test fields. The intrinsic form of the differential and boundary conditions of equilibrium along with the constitutive laws is consistently established. Various forms of the gradient elasticity theory, in the sense of stress or strain gradient models, can be

The paper presents a unified closed-form solution for the lifetime of elastic spherical and cylindrical vessels of arbitrary thickness subjected to pressures of corrosive media at different temperatures. The analysis takes into account the mechanochemical effect, the presence of anti-corrosion coatings, and possible inhibition of corrosion. The life of the vessels is determined by competition of different

In this paper, electrokinetic flow of Newtonian fluids with pressure-dependent viscosity through a nanoslit is investigated. Under the assumption of unidirectional steady flow, taking the dimensionless pressure-viscosity coefficient ɛ as a small parameter, the asymptotic analytical solutions of velocity and pressure up to second order in ɛ, streaming potential and electrokinetic energy conversion (EKEC)

Porous materials are highly relevant in engineering and medical applications due to their enhanced properties and lightweight nature. Current micromechanical models of porous materials can accurately predict the response under the assumptions of small deformations and drained conditions, typically driven by imposed deformations. However, the theoretical framework for the micromechanical modeling of

A machine learning aided non-deterministic damage prediction framework against both 2D and 3D fracture problems is presented in this paper. By introducing a newly developed extended support vector regression (X-SVR) with generalized Dirichlet feature mapping into the phase field crack growth model, a damage assessment method that contains both crack diagnosis and prognosis is designed. Within the proposed

The mixed boundary value problem associated with scattering of obliquely incident water waves by a flexible porous barrier of different barrier configurations is considered here. The originally defined half-plane problem is converted into a quarter-plane problem. Then a novel connection is established between the solution potential of the converted problem and a resolvable potential in the quarter-plane

The heat pulse (flash) experiment is a well-known and widely accepted method to measure the thermal diffusivity of a material. In recent years, it has been observed that the thermal behavior of heterogeneous materials can show deviation from the classical Fourier equation, resulting in a different thermal diffusivity and requiring further thermal parameters to identify. Such heterogeneity can be inclusions

The role of thermodynamics in deriving constitutive equations is unique, and various approaches have been developed in the last decades. In the present paper, the frameworks of Extended Irreversible Thermodynamics (EIT) and Non-Equilibrium Thermodynamics with Internal Variables (NET-IV) are discussed and compared to each other on the basis of a particular problem of rarefied gases. In this comparison

In this paper, we carry out linear stability analysis of a coupled solid–fluid system in a plane Couette flow past an initially stressed neo-Hookean solid at creeping flow limit (Re=0) and arbitrary Reynolds number (Re), as well as for different solid thicknesses. In biological and engineering systems, we often encounter flows past initially stressed deformable solids. For these cases, initial strain

In this paper, a model for the phase change process due to irradiation with an Ultraviolet (UV) light in a mold filled with a viscoelastic fluid in roll-to-roll nanoimprinting lithography is developed. Employing a thermomechanical approach, constitutive equations for the phase change of a mixture of viscoelastic fluid and solid constituents of the polymer are derived. A general model describing phase

This study presents an extensive numerical investigation on the flow phenomena of a blood analogous fluid through an axisymmetric stenosed artery under both steady and pulsatile flow conditions. Most of the previous investigations, carried out for this benchmark problem, used either a simple Newtonian fluid model or a generalized Newtonian (GNF) fluid model like the power-law or Bingham plastic fluid

Within the context of mixture theory, an attempt is made to solve a particular problem of radially directed fluid diffusion through a two-layer thick-walled pre-stressed fibrous hollow cylinder submitted to combined large deformations. With respect to both limitations due to perfect interface hypothesis and particular properties of rubber-fluid mixture, our investigation exhibit new results, which

Hydrostatic, deviatoric, and external field-driven irreversible dissipations have generally been modeled by separated models. However, since all the irreversible dissipations are governed by the laws of thermodynamics, it is possible to describe the coupled multi-irreversible dissipations with a general model. This paper presents a modeling structure of inelastic potential for coupled multi-irreversible

The high-fidelity generalized method of cells (HFGMC) micromechanical analysis is employed for the prediction of microbuckling stresses of composite materials which are composed of elastic–viscoplastic constituents. The inelastic material behavior is represented by a unified viscoplasticity theory which can model non-proportional loading paths, namely it is capable of providing the effect of axial

Exploiting acoustic streaming effects for microfluidic devices has been proven to be important for cell, microparticle and fluid manipulation in many fields such as, biomedical engineering, medical diagnostic devices, cell studies and chemistry. Acoustic streaming is used in acoustofluidic systems for directing and sorting microparticles as well as mixing and pumping fluids. To understand the underlying

A general class of implicit bodies was proposed to describe elastic response of solids, which contains the Cauchy–Green tensor as a function of Cauchy stress. Here, we consider the buckling of solids described by such a subclass of implicit constitutive relation. We present a general linear incremental theory and carry out bifurcation analysis of a uniaxially compressed rectangular layer described

We address the challenging issue of simultaneously finding transverse shear and normal stresses at all points in a plate from a priori known values of the in-plane stresses at plate's interior points. The principle of virtual work is employed to equate the work done by the transverse stresses to the difference between the work done by the external forces (applied surface tractions and body forces)

Microstructural information on damage in a metastable austenitic steel developed under low-cycle fatigue conditions is extracted from the acoustic monitoring of Poisson's ratio supplemented by the eddy current, and, under certain conditions, specific weight data. These data imply that damage has the form of мicropores of strongly oblate, crack-like shapes (aspect ratios of 0.01–0.04). This means that

Microstructural changes under low-cycle fatigue of a metastable austenitic steel are monitored by a combination of the acoustic parameters: Poisson's ratio (more precisely, its change) as indicator of the “diffused” damage and anisotropy change as indicator of changes of texture. Three stages of the Poisson's ratio evolution are identified; they serve as markers of the process of material degradation

The effective field method is applied to solution of the homogenization problem for anisotropic media containing random sets of thin inclusions of low conductivity (crack-like inclusions) or cracks. The derived expression for the tensor of effective conductivity of cracked media on the one hand, takes into account peculiarities of shapes and conductivity of thin inclusions, and on the other hand, reflect

The transformation method is a powerful tool providing the constitutive parameters necessary for arbitrary geometric transformations of solution fields. These constitutive parameters, in elasticity, describe a constitutive law that, unlike conventional Hooke's law, is polar and chiral and that no known solids exhibit. This raises the question of whether polar and chiral elastic solids can be designed

We propose an analytical framework to model the effect of single and multiple mechanical surface oscillators on the dynamics of vertically polarized elastic waves propagating in a half-space. The formulation extends the canonical Lamb’s problem, originally developed to obtain the wavefield induced by a harmonic line source in an elastic half-space. In short, our approach utilizes the solution of the

The purpose of this contribution is to extend the concept of thermoelasticity without energy dissipation traceable back to Green and Naghdi to damped solutions, making use of concrete physical arguments. Specifically, it is assumed that the external rate of supply of heat r, which is formally taken into account in the original model, is such as to include in it an effect of radiation of thermal energy

A model for dry friction is developed based on a model of a shearing layer with a smooth elastic–inelastic transition. The resulting model for friction has a single history-dependent variable that characterizes elastic shear strain in the layer and is determined by integrating an evolution equation for its rate. The model uses an experimentally determined functional form for the coefficient of friction

We propose a new approach for assessing microstructural properties of materials via nondestructive testing (NDT). This approach lies on the observation that, accounting for the microstructure within the materials, reveals a nonclassical band propagation pattern for Love waves. Precisely this propagation structure may be directly related to the internal microstructure. To illustrate this, propagation

The ellipsoidal inhomogeneity with transversely isotropic incoherent interface is considered in the conductivity and elasticity context. The general imperfect interface is modeled by the first order approximation of thin transversely isotropic interphase layer. This model expands the Gurtin et al. (1998) theory of curved deformable interfaces in solids with a nanometer-scale microstructure to the incoherent

In the present study, a novel geometrically exact nonlinear beam model based on the nonlinear displacement field, centerline-inextensibility condition, Euler-Bernoulli beam hypothesis, and modified couple stress theory is established to investigate the extremely large deformations and stability characteristics of size-dependent microcantilevers subjected to a tip-concentrated non-conservative (follower

We consider the implication of allowing the distortion rate in a fluid to be the sum of two smooth components, both incompatible in the sense that they are not gradients of vector fields. Whereas one of these components embodies a smooth distribution of slippage, the other describing the repair needed to ensure that the distortion rate is the gradient of the velocity field. Our considerations lead

Monte Carlo (MC) method is often adopted to calculate the DC conductivity of nanocomposites with straight-line carbon nanotubes (CNT), but calculations for the frequency-dependent AC conductivity and dielectric properties with curved CNTs are rare. The difficulties lie in the geometrical modeling of curved CNTs and the determination of electric potentials for thousands of CNTs and thousands of random

Recent experimental results show that apparent magneto-elastocaloric effect can be induced in the magnetostrictive-shape memory alloy composite system under an ultra-low magnetic field. In this paper, a multiscale theoretical model is constructed to predict the magneto-thermo-mechanically coupled response of such a composite system by considering the multi-field interactions among the heterogeneous

This paper is determined to study the forced vibration response of doubly-curved shells including different shape panels. A power-full higher-order shear-deformation theory in curvilinear coordinate is developed to model the doubly-curved nano-size shell. Furthermore, a general nonlocal strain gradient theory is employed in order to catch up with both phenomena of small-scale behaves. The nanoshell

The topic presented in this research is the calibration of small-scale parameters of non-classical continuum theories such as nonlocal strain gradient theory, strain gradient theory, stress-driven nonlocal elasticity, and strain-driven nonlocal elasticity. Governing equations of vibrational behavior of circular nanoplate and associated boundary conditions for each method derived using Hamilton's principle

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