Habit plane variants (HPVs) are traditionally used as the fundamental microstructure unit in micromechanical models of shape memory alloys. Recently, an approach using Correspondence Variants (CVs) has emerged. Previous research has shown that HPVs cannot completely explain superelastic deformation of Nitinol, especially beyond initiation of the martensitic phase transformation that gives rise to superelasticity

A micropolar peridynamic model is presented for characterizing crack propagation in isotropic and orthotropic brittle materials. The analytical formulation of the two-dimensional model is based on the definition of a micropotential energy function that accounts for the four independent elastic constants that define orthotropy and that in the limit can be reduced to isotropy. A distinctive feature of

High-density polyethylene exhibits discontinuous slow crack growth (SCG) mode in fatigue and creep conditions. To simulate the unique SCG mode, the crack layer (CL) theory can be adopted as an alternative method. However, the stochastic approach is also required for reliability-related problems. In this study, the current deterministic CL model was modified to describe the stochastic discontinuous

The elastic strain and stress fields in an n-layered transversely isotropic cylindrical inclusion surrounded or not by an infinite transversely isotropic cylindrical matrix and subjected to uniform conditions respectively at infinity or on the limit of the n-layered inclusion are derived in a simpler way than before by means of a recently introduced transfer matrix. The interface between the different

Using Bloch-Floquet boundary conditions implies a periodicity in both the spatial and wavenumber domains, causing the numerically computed wavenumbers to be folded or aliased within the Brillouin zone. A methodology is presented to unwrap the wavenumber spectrum to extended Brillouin zones using a Fourier transform method in the spatial domain, thus providing new insights on the physical meaning and

The swelling and drying behavior of a gelatin-glycerol-water hydrogel are examined experimentally for different compositions and different environmental conditions. Significant asymmetry in the swelling and drying kinetics is observed from these measurements. The early time measurements are interpreted first within the context of a linear poroelastic theory, but a fully nonlinear Flory-Rehner theory

Magnetoelectric (ME) coupling is of interest for a variety of applications, but it is weak in a single-phase material. Strain-coupled laminates are an efficient way to achieve a high ME coupling. In this paper, we first derive an exact solution for a simply supported multilayered anisotropic magneto-electro-elastic plate with interfacial magneto-electro-elasticity. It is expressed in terms of the extended

In this paper, we investigate the surface roughness-dependence of buckling of beam-nanostructures. A new variational formulation of buckling of Euler-Bernoulli rough beams is developed based on the Hamilton's principle. The equation of motion of the beam is obtained with a coupling term that depends on the beam surface roughness. Exact solutions are derived for the buckling configurations and the pre-buckling

This work presents a three-dimensional constitutive model for shape memory alloys considering the TRansformation-Induced Plasticity (TRIP) as well as the Two-Way Shape Memory Effect (TWSME) through a large deformation framework. The presented logarithmic strain based model is able to capture the large strains and rotations exhibited by SMAs under general thermomechanical cycling. By using the martensitic

Multistable laminates are potential candidates for adaptive structures due to the existence of multiple stable states. Commonly, such bistable shapes are generated from the cool-down process of the unsymmetric laminates from the curing temperature. In this work, we exploit unsymmetric variable stiffness laminates with curvilinear fiber paths to generate similar bistable shapes as unsymmetric cross-ply

This paper presents the results of 124 pure Mode I fracture toughness tests on two types of anisotropic rocks, the metamorphic Grimsel Granite and the sedimentary Mont Terri Opalinus Clay. The results show that Mode I cracks in anisotropic rocks tend to kink towards the foliation or bedding planes that are weaker in strength. The experiment data for kink angle and apparent fracture toughness are compared

Gradient polyconvex materials are nonsimple materials where we do not assume smoothness of the elastic strain but instead regularity of minors of the strain is required. This allows for a larger class of admissible deformations than in the case of second-grade materials. We describe a possible implementation of gradient polyconvex elastic energies in nonlinear finite strain elastostatics. Besides,

For the investigation of the initial post-buckling of a column built in at one end, clamped in rotation with a flexible support at the other, the stability of the bifurcation point is studied using the Fourier series. The second-order variation of the potential energy is proved to be semi-positive-definite at the bifurcation point. When the disturbance matches the buckling mode, the fourth-order variation

Nanocrystalline NiTi shape memory alloys show fundamental changes in phase transition behavior when the grain size is reduced down to nano-scale (grain size<30 nm). However, due to the extreme difficulties of in-situ experimental observation, universally acknowledged physical mechanisms and detailed microstructures at atomic level are still not clear. In this paper, detailed microstructure images and

NiTi shape memory alloys (SMAs) exhibit distinct thermo-mechanical behaviors affected by the loading frequency, ambient conditions, and the specimen geometry. The effects of these factors are essentially due to the competition of different timescales in phase transitions of NiTi SMAs. However, quantifying the timescale competition still remains a challenge for SMAs subjected to force- or displacement-controlled

One-dimensional vibrating nanostructures show remarkable performance in detecting small adherent masses added to a referential configuration. The mass sensing principle is based on measuring the resonant frequency shifts caused by the unknown attached masses. In spite of its important application in several fields, few studies have been devoted to this inverse eigenvalue problem. In this paper we have

Dielectric elastomer actuators (DEAs) are an emerging type of soft actuator that show many advantages including large actuation strains, high energy density and high theoretical efficiency. Due to the inherent elasticity, such actuators can also be used as soft oscillators and, when at resonance, the dielectric elastomer oscillators (DEOs) can exhibit a peak oscillation amplitude and power output with

Flexible rockfall barriers are protection systems against risks of falling rocks. Their complex behaviour is still not well understood and the development of relevant models allowing for quick calculations is a need toward the optimisation of such structures. The key issue is the modelling of the so-called ”curtain effect”, where the cable net slides along the supporting cables. The present paper proposes

Pseudoelastic NiTi structural components have been shown to exhibit tension/compression asymmetry. Under tension, phase transformation induces localized strains of nearly 7% that spread under nearly constant stress, while under compression the transformation leads to hardening at significantly higher stress, the strain is smaller and grows homogeneously. Bending of tubes ovalizes their cross-section

Understanding the response of solid materials to shock loading is important for mitigating shock-induced damages and failures, as well as advancing the beneficial use of shock waves for material modifications. In this paper, we consider a representative brittle material, BegoStone, in the form of cylindrical bodies and submerged in water. We present a computational study on the causal relationship

Many materials of everyday use are fibrous and their strength is important in most applications. In this work we study the dependence of the strength of random fiber networks on structural parameters such as the network density, cross-link density, fiber tortuosity, and the strength of the inter-fiber cross-links. Athermal networks of cellular and fibrous type are considered. We conclude that the network

Transformation toughening has been used in commercial products for several decades in order to increase the toughness of brittle materials. Composites made from an elastic matrix and elastic-plastic inclusions similarly exhibit increased toughness and R-curve behavior due to the residual stress induced in the wake of the crack tip by the unloaded, plastically deforming fillers. These two mechanisms

Towards understanding the bulk material response in nanocomposites, an interfacial zone model was proposed to define a variety of material interface behaviors (e.g. brittle, ductile, rubber-like, elastic-perfectly plastic behavior etc.). It also has the capability to predict bulk material response though independently control of the interface properties (e.g. stiffness, strength, toughness). The mechanical

Lithographically defined interconnects with filamentary, serpentine configurations have been widely used in various forms of stretchable electronic devices, owing to the ultra-high stretchability that can be achieved and the relative simple geometry that facilitates the design and fabrication. Theoretical models of serpentine interconnects developed previously for predicting the performance of stretchability

In this work the frictionless, adhesive contact between a rigid spherical indenter and an elastic multi-layer coated half-space was investigated by means of an integral transform formulation. The indented multi-layer coats were considered as made of isotropic layers that are perfectly bonded to each other and to an isotropic substrate. The adhesive interaction between indenter and contacting surface

The transient rotation responses of simple, axisymmetric, viscoelastic structures are of interest for interpretation of experiments designed to characterize materials and closed structures such as the brain using magnetic resonance techniques. Here, we studied the response of a Maxwell viscoelastic cylinder to small, sinusoidal displacement of its outer boundary. The transient strain field can be calculated

A new formulation to model the mechanical behavior of high performance fiber reinforced cement composites with arbitrarily oriented short fibers is presented. The formulation can be considered as a two scale approach, in which the macroscopic model, at the structural level, takes into account the mesostructural phenomenon associated with the fiber-matrix interface bond/slip process. This phenomenon

An effective spring stiffness approximation is proposed for a hexagonal array of coplanar penny shaped cracks located at the interface between two dissimilar solids. The approximation is based on the factorization of the solution on the material dissimilarity factor, the crack interaction factor and the effective spring stiffness solution for non-interacting cracks in a homogeneous material. Such factorization

The effect of crack interactions on stress intensity factors is examined for a periodic array of coplanar penny-shaped cracks. Kachanov's approximate method for crack interactions (Int. J. Solid. Struct. 1987; 23(1):23-43) is employed to analyze both hexagonal and square crack configurations. In approximating crack interactions, the solution converges when the total truncation number of the cracks

A novel asymptotic approach to the theory of non-homogeneous anisotropic plates is suggested. For the problem of linear static deformations we consider solutions, which are slowly varying in the plane of the plate in comparison to the thickness direction. A small parameter is introduced in the general equations of the theory of elasticity. According to the procedure of asymptotic splitting, the principal

Reinforcement of fibrous composites by stiff particles embedded in the matrix offers the potential for simple, economical functional grading, enhanced response to mechanical loads, and improved functioning at high temperatures. Here, we consider laminated plates made of such a material, with spherical reinforcement tailored by layer. The moduli for this material lie within relatively narrow bounds