In accordance with hyperelastic transformation theory, a range of shear-wave manipulation devices can be designed with neo-Hookean materials pre-deformed properly. However, how such devices fit the background medium remains elusive. In this study, a systematic formula is developed in terms of elastic wave transmission and reflection between un-deformed and pre-deformed hyperelastic materials. By both

This paper deals with the fatigue of shape memory alloys considering both experimental and theoretical approaches. Initially, experimental tests are performed considering NiTi pseudoelastic wires subjected to different load conditions. Functional and structural fatigue are investigated considering situations related to phase transformations and plastic behavior. Afterward, experimental macroscopic

Equivalent plate properties are obtained for composite corrugated structures using mechanics of structure genome. The method developed in this paper interprets the unit cell associated with the corrugated structure as an assembly of plates, and the overall strain energy density of the unit cell as a summation of the plate strain energies of these individual plates. Mechanics of structure genome is

The application of ductile fracture criteria to shell elements yields invalid after the onset of necking and sensitivity to element size. The mesh-size regularisation strain study indicates that fracture strain modified with element dimension results in the same stress state. This phenomenon can't be accurately explained by current strain based fracture models. To fill this gap, this paper proposed

Detachment of bonded tiles undermines the aesthetics, functionality, and safety of innumerable buildings world-wide. The plate-type interfacial debonding mechanisms that are the root cause of tile detachments are difficult to observe and monitor because they are hidden by opaque external layers. This invisibility, together with the brittle nature of tile detachments, raises questions regarding the

This paper presents a new general methodology to obtain an approximate analytical expression of the Saint-Venant's torsion. The shear stress in each of the principal Cartesian directions is obtained by the derivation of the stress function, whose analytical expression is obtained from the Prandtl analogy. The proposed methodology uses two variables quadratic piecewise functions to define the Prandtl

The present paper aims to show the ability of the extended overstress subloading surface EOSS theory to model the rate-dependency of metallic materials subjected to different loading conditions. The numerical results were carried out by means of Finite Elements FE simulations reproducing pure creep, stress relaxation, monotonic tensile and cyclic loading conditions. A particular emphasis is given to

The commutative-symmetrical elastic-plastic stretch-tensor product and the multiplicative Bilby-Kröner-Lee decompositions of a deformation gradient are compared to one another in particular with respect to the corresponding time derivatives and tensor rates. It turns out that these multiplicative deformation-tensor models differ with respect to the elastic response just for a Lagrangean point of view

Increasing applications of laminated composite structures necessitate the development of equivalent single layer (ESL) models that can achieve similar accuracy but are more computationally efficient than 3D or layer-wise models. Most ESL displacement-based models do not guarantee interfacial continuity of shear stresses within laminates. A possible remedy is the enforcement of interlaminar equilibrium

In this contribution, a probabilistic micromechanics damage framework is presented to predict the macroscopic stress-strain response and progressive damage in unidirectional glass-reinforced thermoplastic polymer composites. Motivated by different failure modes observed experimentally, the damage mechanism in the vicinity of the fibers (namely, the interphase) is characterized by initiating and growing

In this paper, a lattice structure whose mechanical properties can be systematically designed is presented using tailored sub-unit structures made from curved bars. First, the stiffness of circular-arc curved bars is theoretically studied, and the effects of geometric parameters of the curved bars on the mechanical properties are analyzed. Second, sub-unit structures are designed based on the fractal

This paper develops a simple theoretical model for the adhesive contact between a rigid sphere and a circular membrane radially stretched by constant tension. The adhesive stress between the surfaces in front of the contact edge is approximated by a constant value within a finite length. The mutual relations between net external force, contact radius, and contact displacement are obtained analytically

Structures with clustered cables are widespread in many engineering applications. Most existing works involving clustered cables are based on a finite element formulation and do not address cable friction. This paper presents a novel multibody-based methodology for the mechanical analysis of systems containing clustered cable elements. The generalized coordinates of the system are chosen as configurations

In this article an “hyper-reduced” scheme for the Crisfield’s algorithm (Crisfield, 1981) applied to buckling simulations and plastic instabilities is presented. The two linear systems and the ellipse equation entering the algorithm are projected on a reduced space and solved in a reduced integration domain, resulting in a system of “hyper-reduced” equations. Use is made of the Gappy proper orthogonal

Deployable membrane structures such as inflatable stratospheric balloons are known to be sensitive to the occurrence of local instabilities such as wrinkles. The wrinkling phenomenon affects the working performances of the membrane and the occurrence of this phenomenon has to be controlled numerically in order to predict the best means of deployment during the inflation of aerospace balloons. To improve

A solution is derived for a mixed boundary orthotropic elastic plane problem using a mapping function to solve arbitrary configurations. No stress function using a mapping function seems to have been derived. The problem is solved as a Riemann–Hilbert problem. The final exact stress functions are represented by an irrational mapping function as a closed form. Stress components are represented by one

Smart soft materials, which can flexibly respond to external multi-physics stimuli, have attracted considerable attention over the past few years. Here, we present tunable wrinkling patterns in cylindrical core–shell systems under thermal load via the orientation of director in nematic liquid crystal polymer (LCP). To quantitatively analyze mechanical behavior and morphological evolution of LCP core–shell

Dielectric elastomer minimum energy structure (DEMES) formed by clinging a pre-stretched dielectric elastomer (DE) membrane to the compliant frame possess both material and geometrical nonlinearity. The viscous and hyperelastic nature of the DE membrane and coupling between the compliant frame and membrane forms the basis of these nonlinearities. Practically, DE membrane based DEMES actuator executes

A dispersion of stiff and thin (‘rigid line’) inclusions (RLIs) in a matrix material may result beneficial for stiffening in the elastic range, but might be detrimental to strength, as material instabilities may be triggered by inclusions when the matrix is brought to a viscoplastic-damaging state. This dual role of RLIs is investigated by means of the embedded reinforcement model. Validated against

Fracturing two-dimensional random fiber networks of different densities (porosities) were statistically analyzed using both high-resolution finite element models and image analysis algorithms. Under small strains, the finite element fracture models revealed that networks with high relative densities were able to localize evolving fractures to small cracks while surprisingly larger cracks were required

A numerical method for nonlinear steady-state wave scattering due to a crack with contact acoustic nonlinearity (CAN) is developed in this article. The in-plane scattering problem is addressed here. The two systems studied are composed of an unbounded elastic solid that includes an interior crack and an elastic half plane that includes a surface-breaking crack. A time-harmonic plane wave is incident

The helicoidal fibril structures are identified in a variety of naturally occurring species, like the crustaceans. This paper describes a theoretical modelling approach to study the fracture properties and toughening mechanism of the crustaceans-inspired helicoidal structures. First, due to the low fracture resistance of the commonly used carbon fibre reinforced polymers (CFRPs) cross-ply laminates

Magneto-active polymers (MAPs) consist of a polymeric matrix filled with magnetisable particles. MAPs may change their mechanical properties (i.e., stiffness) and/or mechanical deformation upon the application of an external magnetic stimulus. Mechanical responses of MAPs can be understood as the combined contributions of both polymeric matrix and magnetic particles. Moreover, the magnetic response

The crack tip mechanics of strain gradient plasticity solids is investigated analytically and numerically. A first-order mechanism-based strain gradient (MSG) plasticity theory based on Taylor’s dislocation model is adopted and implemented in the commercial finite element package ANSYS by means of a user subroutine. Two boundary value problems are considered, a single edge tension specimen and a biaxially

The contact stiffness between a poro-elastic spherical grain, made out of an open-cell foam, and a plane is studied with the aim of determining the contact law, and in particular verifying if the Hertz interaction potential, originally derived in the frame of continuum mechanics, holds. The contact law is studied experimentally by compressing a half-sphere of melamine foam into a rigid flat surface

In recent years, Dielectric elastomers (DEs) have received much interest for the dynamics applications as waveguide. However, predicting the wave propagation behavior in a DE medium is very challenging due to the complexity of the problem, which involves the delicate interplay between electromechanical coupling, large deformation, and particularly the intrinsic material viscoelasticity. In this paper

The optimal design of the postbuckling response of variable angle tow composite structures is an important consideration for future lightweight, high-performing structures. Based on this premise, a new optimisation tool is presented for shell-type structures. The starting point is an isogeometric framework which uses NURBS interpolation functions to provide a smooth description of the deformed shapes

The derivation by variational asymptotic homogenization of a 2D-continuum model describing large elastic planar deformations of a discrete bi-pantographic structure is presented. A rectangular bi-pantographic specimen was additively manufactured and subjected to a bias extension test for macroscopic strains up to ca. 40%. The deformations of the bi-pantographic sample were measured via FE-based digital

In this work, the energetic formulation for rate-independent dissipative materials is extended to consider non-associative plasticity models. In associative models, the fulfilment of the principle of maximum dissipation naturally leads to a variational formulation of the evolution problem. This is no longer true for non-associative models, which are generally presented in the literature in a non-variational

It is known from experimental findings that three-dimensional effects can have a strong influence on magnetic shape memory behavior. Such phenomena are, however, often neglected in MSMA constitutive models, as they only become meaningful under complex loading conditions. The extensions of our original modeling framework, cf. Bartel et al. (2020), to include 3D-effects is threefold: (i) vector-valued

A tensegrity family is a group of tensegrity structures that share a common connectivity pattern. The three first members of the Octahedron family are the octahedron, the expanded octahedron and the double-expanded octahedron. In this work a new family is presented: the X-Octahedron family. If in the elementary rhombic cells of the Octahedron family a diagonal cable is introduced then X-rhombic cells

Plastic deformations of metallic materials depend on the rate of loading or deformation, implying rate-independent constitutive theories cannot catch a realistic response of the material when the loading condition is not quasi-static. Considering the conventional rate-dependent algorithms, the description of irreversible deformations does not show a smooth transition of the so-called viscoplastic strain

A new approach is proposed for enabling the exchange and testing of arbitrary yield surface models, solely based on a set of Fourier coefficients. This effectively reduces the implementation efforts to a single generic model description. The proposed method exploits the Fast Fourier Transform algorithm to identify a unique set of coefficients of the FAY model based on any plane stress yield surface

In this paper, the nonlinear vibration of a size-dependent doubly clamped NEMS has been investigated based on the consistent couple-stress theory and Euler-Bernoulli beam theory. The impact of surface elasticity, dispersion Casimir force, and fringing field effect are considered in the nonlinear model. Here, the nanobeam is supposed to be under a single-side electrostatic actuation, which is a combination

Reconfigurable surfaces are useful in many applications. This paper proposes a type of reconfigurable surfaces that consist of rigid elements (tiles) connected by novel compliant joints. Depending on the actuation, these novel connecting joints can either operate as torsional hinges, which create isometric transformation (like origami folding) between connected tiles, or bistable translational springs

This paper proposes a theoretical solution for multi-span continuous sliding cable structures, which were usually analyzed by numerical simulations. Firstly, the analytical equation for the unstressed length of single-span cable based on the undeformed configuration is derived, in which the tension forces at the ends can be accurately calculated. Then, according to the tension balance condition at

The motivation of this work is to better understand the dynamic behaviour of bistable structures presenting an analogy with regularized Ericksen bars. The archetype of such structures is the bistable tape spring, which exhibits a particular scenario of deployment, from the stable coiled configuration to the straight stable configuration: at each time of the deployment, the geometry of the tape is similar

In this paper the scattering of incident surface waves by an inclined subsurface crack in a homogenous, isotropic and linearly elastic half-space has been investigated in a two-dimensional plane strain configuration. The elastodynamic reciprocity theorem together with a virtual wave has been used to determine the amplitude of the scattered surface waves in the far field. It is found that the amplitude

We discuss a reduced-order modeling technique based on Fourier series for membrane wrinkling when the orientation of the wrinkles is not uniform. Indeed, the orientation of the wrinkles depends on geometry and loading, for instance in the case of perforated membrane or with non uniform residual stresses. This Fourier-based reduction technique is an extension of the famous Ginzburg-Landau equation and

Soft robot arms remain challenging to model effectively. The arm’s primary deformation is bending, coupled with extension or compression, but the strains experienced can be high, the materials are generally nonlinear, and the deformations are large. Existing work has focused on models intended to improve control, which rely on post-manufacturing empirical characterization of each arm design. This article

This article focuses on predicting the instant of failure in a real scale component of complex geometry and loading using a ductile damage model calibrated exclusively on small-scale laboratory specimens of relatively simple shape. The ductile behaviour of a strain hardened aluminium alloy AA1050, formed into a thin-walled component, is modelled by a coupled ductile fracture locus model presented in

In this study, a computational framework is proposed for thermomechanical contact and debonding problems with proper thermal resistance at the interface. Using the Variational Multiscale (VMS) framework, we present a fully coupled thermomechanical formulation with an explicit expression of the pressure at the contact interface. The formulation considers the quasi-static balance of the momentum and

Two-dimensional lattices are ideal candidate for developing artificially engineered materials and structures across different length-scales, leading to unprecedented multi-functional mechanical properties which can not be achieved in naturally occurring materials and systems. Characterization of effective elastic properties of these lattices is essential for their adoption as structural elements of

Dynamic strain aging (DSA) widely exists in austenitic stainless steel at elevated temperature. The materials will be drastically strengthened by this phenomenon. A series of symmetric strain-controlled and asymmetric stress-controlled cyclic experiments were conducted at different temperatures from 293K to 823K for 316LN stainless steel. The DSA phenomenon was observed in all the tests under elevated

A finite-element approach based on the first-order FE2 homogenisation technique is formulated to analyse the alkali-silica reaction-induced damage in concrete structures, by linking the concrete degradation at the macro-scale to the reaction extent at the meso-scale. At the meso-scale level, concrete is considered as a heterogeneous material consisting of aggregates embedded in a mortar matrix. The

Basic knowledge of the deformation behavior of fabricated components is of paramount importance in materials processing. Compared to other process methods, the mechanics of metal imprinting, especially at small scales, have received relatively less research attention. However, recent demands for tuning the properties of metal surfaces by forming undulated micropatterns have spurred interest in gaining

Alkali-Silica Reaction (ASR) is a particular type of chemical reaction in concrete, which produces cracking and overall expansion of the affected structural element due to the formation of expansive reaction products within the cracks. This paper develops the formulation of a coupled Chemo-Mechanical (C-M) Finite Element (FE) model for simulating ASR expansions in soda-lime glass concrete at the meso-scale

A conjugate beam analogy is here proposed to evaluate the shear coupling in three-layered laminates formed by two external elastic plies bonded by a compliant interlayer. Based on the formal analogy of the governing equations, the method allows the evaluation of the shear coupling in the external plies by studying the response of a monolithic conjugate beam under a tensile constant axial force and

Insulating Glazing Units (IGUs) are glass panes held together by structural edge seals, entrapping a gas for thermal and acoustic insulation. The bending of one pane induces pressure variations in the cavities, which produce the load sharing through the gas with the other panes. Under mild hypotheses, the whole IGU behaves as a linear elastic system. Hence, for IGUs with panes and cavities of any number

In this effort, the interfibrillar behavior in UHMWPE fibers subjected to tension is investigated using a unique experimental setup that allows for the in-situ monitoring of the deformations of sub-fiber level components within the fiber. Digital image correlation (DIC) is used to measure fiber surface strains, quantify the stress-strain fiber response and interfibrillar sliding between adjacent macrofibrils

Functionally Graded Materials (FGMs) are characterized by the distribution in composition and structure gradually over volume, which were recently designed and developed as a key component of a multifunctional building envelope for the high performance of energy efficiency. It was realized by mixing aluminum particles and fine High-Density Polyethylene (HDPE) powders through a vibration-sedimentation

In this paper an approximate analytical solution for constrained high-pressure torsion problem is proposed. The finite-strain elastic–plastic model based on multiplicative split of deformation gradient tensor is utilized. Plastic deformation is described by non-associative flow rule. Thus, the dependence of the plastic properties of the material on pressure is taken into account. The problem is reduced

An unbounded elliptically orthotropic elastic solid containing a single anisotropic ellipsoidal inhomogeneity is considered. The problem statement assumes arbitrary orientation of ellipsoid with respect to the orthotropy axes and non-uniform far loading. By applying the appropriate affine transformations, the boundary value problem is reduced to that one with the isotropic constituents. The complete