Sequestration of carbon dioxide (CO2) in deep saline aquifers has emerged as an option for reducing greenhouse gas emissions to the atmosphere. The large amounts of supercritical CO2 that need to be injected into deep saline aquifers may cause large fluid pressure increases. The resulting overpressure may promote reactivation of sealed fractures or the creation of new ones in the caprock seal. ...

A model for the elastic-viscoplastic response of metallic single crystals is developed on the basis of the modern finite-deformation theory of plasticity combined with considerations of material symmetry. This is proposed as an alternative to conventional crystal plasticity theory, based on a decomposition of the plastic deformation rate into a superposition of slips on active slip systems. A s...

The hysteresis or internal friction in the deformation of crystalline solids stressed cyclically is studied from the viewpoint of collective dislocation dynamics. Stress-controlled simulations of a dislocation dynamics model at various loading frequencies and amplitudes are performed to study the stress-strain rate hysteresis. The hysteresis loop areas exhibit a maximum at a characteristic freq...

Numerical studies of the ductile-brittle transition are described that are based on incorporating physically based models of the competing fracture mechanisms into the material's constitutive relation. An elastic-viscoplastic constitutive relation for a porous plastic solid is used to model ductile fracture by the nucleation and subsequent growth of voids to coalescence. Cleavage is modeled in ...

An optimal control problem is considered for the variational inequality representing the stress-based (dual) formulation of static elastoplasticity. The linear kinematic hardening model and the von Mises yield condition are used. Existence and uniqueness of the plastic multiplier is rigorously proved, which allows for the re-formulation of the forward system using a complementarity condition. I...

Abstract In this paper a selected type of elasto-viscoplastic constitutive equations is considered. The viscoplastic model which was proposed by Marquis generalized allowing multiple terms describing the isotropic and kinematic hardening. Furthermore, presented formulation enables one to use an arbitrary equivalent plastic strain function describe hardening behavior. What more, backstress evolu...

The concept of the local approach is applied to investigate different damage mechanisms of structural steels by micromechanical material models. Static and dynamic fracture resistance curves for a neutron-embrittled weld material are derived from tensile and Charpy-type specimens with the modified Gurson model. The behaviour of a test piece with a crack in the fenitic base material beneath an a...

The determination of the effective or macroscopic properties of composite materials from the corresponding local properties of the constituent phases and the underlying sub-structure constitutes the fundamental problem in Mechanics of Composites. This problem is motivated from the remarkable physical observation that the constitutive properties of these materials appear to be homogeneous or uni...

In this study, the effects of random laminate misalignment on macroscopic and microscopic elastic/viscoplastic behaviors ultrafine plate–fin structures are statistically investigated adopting Monte Carlo simulation. To end, a multiscale method that analyzes elastic–viscoplastic behavior with both macroscopically microscopically is proposed based homogenization theory for nonlinear time-dependen...