We consider numerical approximations of a class of abstract nonlinear evolutionary systems arising in the study of quasistatic frictional contact problems for elastic-viscoplastic materials. Both spatially semi-discrete and fully discrete schemes are analyzed with the nite element method employed to discretize the spatial domain. Strong convergence of both approximations is established under mi...

We consider a class of abstract nonlinear evolution systems arising in the study of quasistatic frictionless contact problems for elastic-viscoplastic materials. The variational analysis of such systems, including existence and uniqueness results as well as some properties concerning the behavior of the solution, has been done in 12]. In this paper we consider numerical approximations of this c...

The algorithmic consistency conditions are derived which yield the plastic loading index for the combined isotropic– kinematic hardening plasticity with the Armstrong–Frederick evolution equation for the back stress. Rate-independent elastic–plastic, and rate-dependent viscoelastic–plastic and elastic–viscoplastic material models are all encompassed by the analysis. The directions of the plasti...

We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels which we proposed in a previous paper (Nature Mater. 5, 552 (2006)), which attributes decohesion to the viscoplastic pull-out of the networ...

This contribution is focused on the Mullins effect in polyethylene. An ultra-low-density polyethylene with 0.15 crystal content, a low-density polyethylene with 0.3 crystal content and a high-density polyethylene with 0.72 crystal content are subjected to cyclic stretching over a large strain range. Experimental observations are first reported to examine how the crystal content influences the M...

This paper deals with full face excavation of large size tunnels in rock masses of very poor quality which exhibit squeezing problems. Three different time dependent constitutive models of increasing complexity (a viscoelasticplastic model, an elastic-viscoplastic model, and an elastic-plastic-viscoplastic model) are used to analyze the tunnel response during excavation of the Saint Martin La P...