It is crucial to understand the creep behavior of Pb-free solder alloys in electronic packaging. Typical service environments are between 298 and 373K. The thermal mismatch induced stresses acting on solder joints result in extensive rate-dependent plastic deformation. The solder alloy is potentially the weakest component in the electronic package because normal operating temperatures are alrea...

We study thermomechanical deformations of a viscoplastic body deformed in simple shear. The strain gradients are taken as independent kinematic variables and the corresponding higher order stresses are included in the balance laws, and the equation for the yield surface. Three different functional relationships, the power law, and those proposed by Wright and Batra, and Johnson and Cook are use...

A granular front emerges whenever the free-surface flow of a concentrated suspension spontaneously alters its internal structure, exhibiting a higher concentration of particles close to its front. This is a common and yet unexplained phenomenon, which is usually believed to be the result of fluid convection in combination with particle size segregation. However, suspensions composed of uniforml...

This study deals with the viscoplastic behavior of a porous polycrystal pores and grains similar sizes. Such microstructure can be encountered in irradiated nuclear Mixed OXide (MOX) fuel materials. MIcronized MASter blend (MIMAS) MOX are multi-phase materials mainly composed two or three phases depending on their fabrication process. One these corresponds to plutonium-rich agglomerates which s...

We examine theoretically the spread of a jet impacting on circular disk and hydraulic jump viscoplastic fluid Herschel–Bulkley type. The depth-averaging approach is employed in supercritical region, subcritical flow assumed to be inertialess lubrication treated as shock, where balance mass momentum established radial direction, including effect surface tension across jump. show that, contrast N...

Abstract In continuum mechanics, viscous materials are those that lack rigidity and elastic response under shear stress. We argue using the term to refer aseismic lithosphere is thus a misnomer because it denies propagation of S waves through in total contradiction decades seismic surveys. Similarly, yield stress, which another feature expected most situations within but more difficult assess. ...

An elasto-viscoplastic constitutive model was previously developed and successfully used to describe the anisotropic time-dependent response of short fiber reinforced thermoplastics. It is demonstrated that when it applied systems with a higher level anisotropy, apparent anisotropy rate-dependent yield stress deviates from Hill parameters are define it. This becomes more if increased. The origi...

A finite strain micromechanical model is generalized in order to incorporate the effect of evolving damage in the metallic and polymeric phases of unidirectional composites. As a result, it is possible to predict the response of composites with ductile and brittle phases undergoing large coupled inelastic-damage and viscoelastic-damage deformations, respectively. For inelastic composites, both ...

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...