An ionic polymer-metal composite ~IPMC! consisting of a thin Nafion sheet, platinum plated on both faces, undergoes large bending motion when an electric field is applied across its thickness. Conversely, a voltage is produced across its faces when it is suddenly bent. A micromechanical model is developed which accounts for the coupled ion transport, electric field, and elastic deformation to p...

We consider the mechanical response of random, heterogeneous materials, where each phase is elastic-plastic with an associated flow rule, and the microstnrcture’s statistics is homogeneous and ergodic. Under proportional monotonic loading, the effective (in the macroscopic sense, or overall) elastoplastic response is shown to be bounded from above and below by those obtained, respectively, from...

The problem of development microequipment is discussed. This paper contains description of the main problems connected with micro mechanical equipment developing, requirements to the micro machine tools properties, design and control systems of the prototypes of first generation machine tools, and applications of micro equipment. The mayor idea of this paper is to show the experience of the Lab...

A multiphysics micromechanics model is developed to predict the effective properties as well as the local fields of periodic smart materials responsive to fully coupled electric, magnetic, thermal and mechanical fields. This work is based on the framework of the variational asymptotic method for unit cell homogenization (VAMUCH), a recently developed micromechanics modeling scheme. To treat the...

This document describes a recently developed analysis tool that enhances the resident capabilities of the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) (Refs. 1 to 3) and its application. MAC/GMC is a composite material and laminate analysis software package developed at NASA Glenn Research Center. The primary focus of the current effort is to provide a graphical u...

One of the most common load modes is flexure. The paper measures and models flexural strength modulus a bio-polyethylene reinforced with thermos-mechanical fibers from corn stover. Moreover, authors use modified rules mixtures to evaluate contribution reinforcements properties composite. It was found high impact coupling agent content on composites, materials 6% such 50% reinforcement increased...

Conceptually simple and computationally most efficient polygonal computational grains with voids/inclusions are proposed for the direct numerical simulation of the micromechanics of piezoelectric composite/porous materials with non-symmetrical arrangement of voids/inclusions. These are named “Multi-Physics Computational Grains” (MPCGs) because each “mathematical grain” is geometrically similar ...

A Hashin–Shtrikman–Willis variational principle is employed to derive two exact micromechanics-based nonlocal constitutive equations relating ensemble averages of stress and strain for two-phase, and also many types of multi-phase, random linear elastic composite materials. By exact is meant that the constitutive equations employ the complete spatially-varying ensemble-average strain 6eld, not ...