One of the most challenging issues in the automotive industry is to reliably predict the fracture limits across a broad range of the deformation modes subjected to various forming processes. Sheet metals in general exhibit anisotropy in both their deformation and fracture behaviors, and accordingly the stress and strain states at fracture strongly depend on both the loading condition and direction

This paper critically examines the predictive capabilities of three computational approaches for the elastic-plastic response of nanoporous materials with energetic surfaces simulated with the Gurtin-Murdoch coherent interface model. These approaches involve the classical composite cylinder assemblage model, and the finite-element and generalized finite-volume homogenization theories. Exact elastic-plastic

The main attraction of metallic nanolayered composites (MNCs) lies not only with their five-to ten-fold increases in strength over that of their constituents, but also in the tunability of their superior strength with nanolayer thickness. While the size scaling in strength prevails in many MNC material systems, the size scaling cannot be accurately predicted with crystal plasticity framework. Here

Plasticity in body centered cubic (BCC) crystals is shown to be controlled by slow screw dislocation motion, owing to the thermally-activated process of kink pair nucleation and migration. Through three dimensional discrete dislocation dynamics simulations, this work unravels the mystery of how such slow screw dislocation behavior contributes to extremely rapid strain bursts in submicron BCC tungsten

Orientation-dependent irradiation hardening phenomena in pure Zr have been studied, and the corresponding mechanisms investigated based on the combined use of SEM, TEM, and CPFEM. Nanoindentation was conducted on ten grains at room temperature before and after ion irradiation (0.3 dpa, 250 °C). The hardness decreases as the declination angle (the angle between c-axis and sample surface normal) increases

Shape Memory Alloys (SMAs) have the main interesting property to recover an inelastic strain induced by martensitic transformation. The initial shape can be recovered directly after unloading or with the application of an additional heating. Iron-based SMAs (Fe-SMAs) are characterized by a high coupling between phase transformation and plastic slip at low temperatures under small stress levels. Thermomechanical

Single crystal plasticity plays a major role in the analysis of material anisotropy and texture evolution, treats each crystalline grain individually. The polycrystalline material response is obtained upon considering a structure consisting of various individual grains, often also considering interface effects at the grain boundaries. On the individual grain level, single crystal plasticity can be

Both experiments and theoretical investigations have evidenced the existence of compressive-shear fracture mode in geomaterials like concrete, rocks and gypsum. Proper description and modeling of intricate fracturing pattern with consideration of strong tension-compression asymmetry in mechanical response remain an open issue in phase-field modeling and simulation. In this work, a new phase field model

The interfaces introduced in metals by heterostructural design play crucial roles in mechanical behaviors. Here the effect of gradient interfaces on mechanical behavior was investigated in a laminated Cu–30Zn sample composed of coarse-grained and ultrafine-grained layers. Tensile tests revealed a superior strength-ductility synergy with extraordinary strengthening and work hardening. By combining the

It is well known that twinning likely nucleates and forms pairs at grain boundaries (GBs) during the deformation of Mg alloys. Therefore, the crystallography of GBs plays an important role in selecting twin variants. In this regard, the Schmid factor (SF) cannot predict from which GBs twinning prefers to nucleate. To solve this problem, a composite Schmid factor (CSF) is proposed in this paper that

A large class of rock-like materials are composed of a plastic solid matrix in which various inclusions and pores are embedded. This paper is devoted to determine macroscopic inelastic responses of such materials by a nonlinear homogenization procedure. The plastic behavior of solid matrix is described by a plastic model based on the pressure-dependent Drucker-Prager criterion. The plastic strain field

It has been proposed that a plastic strain surface is reset to a point and re-evolves every cycle to correctly evaluate the plastic strain range under cyclic loading (Ohno et al., 2018b). This resetting scheme has the advantage of providing a definite value for the evolution parameter irrespective of the amounts of cyclic hardening, pre-straining, and ratcheting. In the present study, the resetting

In this contribution, for the first time, the effect of crystal orientation on the critical stress for martensitic transformation in a medium Mn steel is explicitly revealed by using micropillar compression experiments. Although the martensitic transformation is observed in both [100] and [110] micropillars during compression tests, the average critical stress for martensitic transformation in [100]

Commonly implemented material processing routines not limited to quenching, welding or heat treatment requires exposure of a part to complex thermal and mechanical loading histories that manifest as residual stress and distortion. Of interest to material designers and fabricators is modeling and simulating the evolutionary process a part undergoes for the sake of capturing this observable residual

This paper investigates the intergranular deformation behavior and its effect on the overall ductility of a Mg-Gd-Y alloy, using in-situ tension in scanning electron microscopy (SEM) combined with electron backscattered diffraction (EBSD) and digital image correlation (DIC) techniques. At regions surrounding grain boundaries, the majority of activated dislocation slip traces were found to form in pairs

A model is proposed explaining enhanced strength of ultrafine-grained alloys that contain grain boundary (GB) solute segregations. In the framework of the proposed model these segregations are treated as homogeneous ellipsoidal inclusions and act as the sources of elastic stresses affecting the emission of lattice dislocations from GBs. These segregations pin the ends of lattice dislocation segments

A model for distorting the yield surface by flattening the part in the reverse of the loading direction, is suggested. As the basis for the distortion, the model applies a pair of second-order back-stress tensors of similar type as in kinematic hardening models. The yield-surface formulation provides a flattening and shrinkage of a given first-order homogeneous yield surface in the reverse directions

Directional anisotropic hardening under non-proportional loading is modeled. A recently proposed coupled quadratic-nonquadratic (CQN) yield function (Lee et al., 2017b) successfully captured the directional hardening behavior under the proportional loadings. This paper shows a constitutive equation to capture both directional hardening response and Bauschinger effect through an extended model of the

A new mathematical modelling framework for simulation of metal cyclic plasticity is proposed and experimental validation based on tension-compression cyclic testing of S355J2 low carbon structural steel presented over the two parts of this paper. The advantages and limitations of the stress-strain curve shape modelling given by “Armstrong and Frederick” type hardening rules are discussed and a new

The second part of the study presents development of the Dirac delta functions framework to modelling of cyclic hardening and softening of material during cyclic loading conditions for the investigated in Part I low carbon S355J2 steel. A new criterion of plastic strain range change is formulated. This provides more certainty in the cyclic plasticity modelling framework compared to classical plastic

Despites of some efforts in deformation simulations by the Phase field crystal (PFC) method, simulations of phase transitions and plasticity of crystals under continuous deformations are still lack and some related fundamental issues remain open as well, for example the definition of stresses and the non-zero stresses of unstrained system. In the present work, we propose a deformation simulation method

The ability to predict the formation of twin variants during deformation is essential for modelling the mechanical response of a material. The present study aims to provide a criteria for twin variant selection in an α-Zr alloy. Here Zircaloy-4 was uniaxially deformed at 25 and 300 °C to strain of 0.10 leading to formation of {101¯2}1¯011 tensile twins. Twin variants were characterized using electron

In elastic and plastic deformation of glassy polymers and with the increase of deformation, the material would exhibit elastic, viscoelastic, and viscoelastic-viscoplastic (VE-VP) responses in sequence. These deformation behaviors should be constitutively modeled in such a way to accurately and efficiently simulate many important physical behaviors and phenomena involved in polymer deformation and

This paper deals with molecular ordering in polymers that exhibit strain-induced phase transformation accompanied with plastic yielding. The study is motivated by the anisotropic effects caused by the molecular ordering during the progressive strain-hardening, and thus attempts to contribute to the understanding of the strengthen mechanisms in initially isotropic glassy polymers. The application is

High strength titanium alloys are generally used in widespread applications ranging over, but not limited to biomedical, aerospace, automotive, marine, oil and gas, and energy. Besides other manufacturing processes, forming is one of the common manufacturing process used to produce components out of these alloys. Forming processes generally involve significant plastic deformation of material under

Nanoindentation has been used for a long time to investigate the mechanical properties of materials. A well-known displacement burst, the so-called “pop-in,” is usually observed during nanoindentation tests. In particular for the first pop-in has been well studied because it should be directly related to the fundamental mechanical strength of the local volume beneath the indenter. The first pop-in

The mechanical behaviors of commercially pure titanium (CP–Ti) sheets under uniaxial and reverse loadings along various in-plane directions are investigated by crystal plasticity modeling together with experiments. The elastic viscoplastic self-consistent (EVPSC) crystal plasticity model, that incorporates an enhanced twinning and detwinning (TDT) scheme to consider multiple twinning modes, is employed

The single crystal elastic anisotropy is one of the most important properties affecting the macroscopic response of polycrystalline materials, both in the elastic regime and the early stages of plastic deformation. In this work, the impact of monocrystalline parameters on the mechanical behaviour of cubic polycrystals is studied in detail. The analysis is conducted with an RVE-based computational homogenisation

A thermo-elastic-viscoplastic-damage model based on thermodynamics is developed to describe the self-heating and stress-strain behavior of thermoplastic polymers under tensile loading. The constitutive model considers temperature-dependent elasticity, nonlinear viscoplastic flow and damage evolution. The model includes the important self-heating of a polymer caused by the viscoplasticity and the often

Intragranular failure plays an important role in the failure process of superhard nanocrystalline ceramics. But the atomistic deformation mechanisms leading to intragranular failure have not been well established. Here we performed large-scale reactive force field (ReaxFF) reactive molecular dynamics (RMD) simulations on the finite shear deformation of nanocrystalline boron carbide (n-B4C) with a grain

This paper describes the main results from an experimental investigation into the consequences of various microstructural features, created by laser powder bed fusion (LPBF) and subsequent heat treatments (HTs), in alloy Mar-M-509 on several aspects of plastic deformation including mechanical anisotropy and elongation-to-fracture (ETF). To ensure successful manufacturing of the alloy, porosity fraction

Crystal plasticity-finite element method (CP-FEM) is now widely used to understand the mechanical response of polycrystalline materials. However, quantitative mesh convergence tests and verification of the necessary size of polycrystalline representative volume elements (RVE) are often overlooked in CP-FEM simulations. Mesh convergence studies in CP-FEM models are more challenging compared to conventional

A number of constitutive models have been developed for solid polymers to describe the large deformation behavior. However, most of the existing models rely on a purely elastic or hyperelastic initial response when they are incapable of accurately predicting the cyclic stress-strain hysteresis loops. In this work, therefore, a compact cyclic viscoelastic-viscoplastic constitutive model is proposed

This is the first of a two part paper that systematically develops a finite deformation elasto-plastic, parametrically homogenized constitutive model (PHCM) for structural-scale macroscopic simulations of Titanium alloy Ti6242S. The PHCMs are thermodynamically consistent, reduced-order continuum models that incorporate functional forms of representative aggregated microstructural parameters (RAMPs)

In this second of the two-part paper on the development of Parametrically Homogenized Constitutive Models (PHCMs), constitutive coefficients are represented in functional forms of the representative aggregate microstructural parameters (RAMPs), e.g. texture intensity parameters, misorientation parameter and grain size, identified in the first part (Kotha et al., 2019). Efficient and accurate PHCMs

The tensile properties of additively manufactured (AM) metals and alloys are among the most important variables that impact the potential applications of these materials. Here we examine and report on the tensile properties of AM 316L stainless steels fabricated by the laser powder-bed-fusion (L-PBF) technique, via twelve sets of optimized laser processing parameters that produce materials with density

The steady state is expected when applying severe plastic deformation (SPD) techniques to process metals. In this study, we propose a method to study the steady state regarding the microstructural features and the mechanical properties, which are verified by the experimental results. More importantly, the initial state of as-prepared metal depending mainly on the processing conditions is critical for

A dislocation mechanics based isotropic strain gradient plasticity model is developed. The model is derived from self-energies of dislocations and the Taylor model for plastic dissipation. It is shown that the same microstructural length scale emerges for both the energetic and the dissipative parts of the model. Apart from a non-dimensional factor of the order of unity, the length scale is defined

We consider a mesoscale continuum model for the evolution of dislocation density in small-strain crystal plasticity. The model is based on the continuum dislocation dynamics theory and extended by a formulation for impenetrable grain boundaries. We introduce a fully coupled numerical method combining a conforming finite element approximation of elasto-plasticity with an implicit Runge-Kutta discontinuous

It has been shown in experiments that self-climb of prismatic dislocation loops by pipe diffusion plays important roles in their dynamical behaviors, e.g., coarsening of prismatic loops upon annealing, as well as the physical and mechanical properties of materials with irradiation. In this paper, we show that the dislocation dynamics self-climb formulation that we derived in (Niu et al., 2017) is able

This paper outlines a single crystal plasticity theory for the mesoscale resolution of the diffusionless transformation process of deformation twinning. Unlike prevalent crystal plasticity models of lattice transformation that characterize volume fraction evolution of coexisting parent and product lattices at a material point, our model alternates between two deformation gradient decompositions, depending

Machine learning techniques are widely used to understand and predict data trends and therefore can provide a huge computational advantage over conventional numerical techniques. In this work, an artificial neural network (ANN) model is coupled with a rate-dependant crystal plasticity finite element method (CPFEM) formulation to predict the stress-strain behavior and texture evolution in AA6063-T6

Nanostructured and architectured copper niobium composite wires are excellent candidates for the generation of intense pulsed magnetic fields (∼100T) as they combine both high strength and high electrical conductivity. Multi-scaled Cu-Nb wires are fabricated by accumulative drawing and bundling (a severe plastic deformation technique), leading to a multiscale, architectured, and nanostructured microstructure

This work adapts a recently developed multi-level constitutive model for polycrystalline metals that deform by a combination of elasticity, crystallographic slip, and deformation twinning to interpret the deformation behavior of alloy WE43 as a function of strain rate. The model involves a two-level homogenization scheme. First, to relate the grain level to the level of a polycrystalline aggregate