We present a class of constitutive updates for general viscoplastic solids including such aspects of material behavior as nite elastic and plastic deformations, non-Newtonian viscosity, rate-sensitivity and arbitrary ow and hardening rules. The distinguishing characteristic of the proposed constitutive updates is that, by construction, the corresponding incremental stress-strain relations deriv...

The problem of steady-state penetration by a semi-infinite, rigid cylindrical penetrator with an ellipsoidal nose into an infinite, rigid-viscoplastic target has been studied. The target material is assumed to obey a generalized form of Von Mises yield criterion to account for the strain-rate dependence. Contact between target and penetrator is assumed to be smooth. Computed results show that t...

We observe a new type of behavior in a shear-thinning yield stress fluid: freestanding convection rolls driven by vertical oscillation. The convection occurs without the constraint of container boundaries, yet the diameter of the rolls is spontaneously selected for a wide range of parameters. The transition to the convecting state occurs without hysteresis when the amplitude of the plate accele...

We propose a dynamical theory of low-temperature shear deformation in amorphous solids. Our analysis is based on molecular-dynamics simulations of a two-dimensional, two-component noncrystalline system. These numerical simulations reveal behavior typical of metallic glasses and other viscoplastic materials, specifically, reversible elastic deformation at small applied stresses, irreversible pla...

Recent advances in non-contact strain measurement techniques and large-strain constitutive modeling of the Linear Low-Density Polyethylene film used in NASA Superpressure balloons, StratoFilm 420, are combined to provide a novel measurement technique for the tear propagation critical value of the J-integral. Previously these measurements have required complex test configurations and procedures....

Using a general theory for evolution inclusions, existence and uniqueness theorems are obtained for weak solutions to a frictional dynamic contact problem for elastic visco-plastic material. An existence theorem in the case where the friction coefficient is discontinuous is also presented.