This study investigates the effect of material parameters of the Gurson-Tvergaard-Needleman (GTN) model on the failure prediction of cellular structures. The effect of elastic modulus, calibration parameter of GTN model, isotropic hardening, fracture strain, and strut diameter on the load-displacement curve of a lattice structure fabricated by Selective Laser Melting (SLM) has been studied by u...

The question of ‘generalization’ to finite strains of the constitutive relations of infinitesimal strain theory of elasticity, and classical elasto-plasticity with isotropic and kinematic hardening, is critically examined. Simple generalizations, which lead to physically plausible material behaviour, are presented. The current controversies surrounding (i) the choice of stress-rate in the above...

Cement stabilization has been widely used for improving the strength and stiffness of soft clayey soils. Cement treated soil specimens used to investigate the stress-strain behaviour in the laboratory study are usually cured for 7 days. This paper examines the effects of curing time on the strength and stress strain behaviour of cement treated marine clay under triaxial loading condition. Labor...

The boundary value problem representing one time step of the primal formulation of elastoplasticity with positive hardening leads to a variational inequality of the second kind with some non-differentiable functional. This paper establishes an adaptive finite element algorithm for the solution of this variational inequality that yields the energy reduction and, up to higher order terms, the R−l...

In this paper the ratcheting behavior of carbon steel(ASTM A106B) and stainless steel(304L) elbows is studied under steady internal pressure and in-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear isotropic/kinematic (combined) hardening model has been used to evaluate ratcheting behavior of the elbows. Material parameters have...

Hardening plasticity has a long history in constitutive modelling, with many applications in geomechanics. Mathematical models of non-hardening plasticity involve the definition of a single stationary yield surface in stress-space. Examples include the conventional models of elasto-plasticity, often based on the yield criteria of Tresca, von Mises, and Mohr-Coulomb. Within the yield surface the...

A study on the prediction of springback angle is presented, with focus on the straight flanging operation. The objective is to evaluate the reliability of different ways of prediction. An experiment of straight flanging operation is conducted. Major prediction approaches such as analytical model, numerical simulation using Finite Element Method (FEM) and Meshfree Method are discussed. A set of ...

The mechanical constitutive behavior of geomaterials is quite complex, involving pressure-sensitive yielding, differences in strength in triaxial extension vs. compression, the Bauschinger effect, dependence on porosity, and other factors. Capturing these behaviors necessitates the use of fairly complicated and expensive non-linear material models. For elastically isotropic materials, such mode...

We study axisymmetric thermomechanical deformations of a thick target being penetrated by a fast-moving rigid cylindrical rod with a hemispherical nose, and presume that target deformations appear steady to an observer situated at the penetrator nose tip. Both isotropic and kinematic hardening of the target material are considered. It is found that kinematic hardening increases the normal stres...

A fully modularized framework was established to combine isotropic, kinematic, and cross hardening behaviors under non-monotonic loading conditions. Three sets of state variables were defined and applied to consider the effects of, a) loading history, b) twinning and de-twinning and c) different pre-strain. Experiments under two types of nonproportional loading conditions were conducted along d...