In the present work, large deformation rate-dependent constitutive behavior of isotactic polypropylene is studied via an experimentally validated macroscale model. To analyze nonlinear response material, mechanical tests are conducted at room temperature and a phenomenological model proposed to describe viscoplastic yielding damage semicrystalline polymer. The based on finite elastic-viscoplast...

An efficient numerical integration scheme is proposed for the uniaxial loading of two-layer viscoplastic (TLVP) model, which a built-in material model in commercial finite element software Abaqus. The particular version TLVP under investigation governed by linear isotropic plastic hardening rule with time-hardening nonlinear creep law. new can be easily implemented any programming environment l...

In this study a non-associated viscoplastic flow rule (NAVFR) with combining von Mises and Tresca loci in place of yield and plastic potential functions and vice verse is presented. With the aid of fully implicit time stepping scheme and discussing the other studies on plastic potential flow rules and also experimental results it is shown that the proposed NAVFR can be adopted to forecast the e...

An asymptotic model is constructed to describe the bending of thin sheets, or plates, viscoplastic fluid described by Herschel–Bulkley constitutive law, which incorporates von Mises yield condition and a nonlinear viscous stress. The reduces number previous ones from plasticity theory mechanics in various limits. It characterized criterion proposed Ilyushin compactly combines effect moment in-p...

In recent years, important efforts have been focused on rapid production of tools using Rapid Prototyping and Manufacturing (RP&M) technologies such as the Stereo-Lithography Apparatus (SLA). One of the applications is the development of rapid polymer tooling such as dies for injection molding. For these applications, optimal thermal as well as mechanical properties of final tools are of signif...

Miniaturization of electronics to the nanoscale brings new challenges. Because of their small size and immense information and power processing capacity, large temperature gradients exist across nanoelectronics and power electronics solder joints. In this paper, a fully coupled thermomechanical-diffusion model is introduced to study the thermomigration induced strength degradation. A nonlinear ...

This paper presents failure analysis of solder joints with a damage-coupled viscoplastic model. A material model is developed to characterize the elasticity, plasticity, creep and damage of solder. A semiimplicit time-integration approach is adopted for the numerical implementation of the solder model. This solder model has been implemented into nite element codes developed at Sandia National L...