INTRODUCTION Although the role of viscoelasticity in muscle mechanics is well recognized, methods for measurement in situ are limited. Recent advances in elastography have made possible the imaging of viscoelastic moduli within individual muscles [1, 2]. We have investigated a new approach, supersonic shear imaging (SSI), which combines high frame-rate (5kHz) ultrasound with acoustic radiation ...

A proof of convergence of the finite-element method in rate-type, quasistatic boundary value problems is presented. The bodies considered may be discretely heterogeneous and elastically anisotropic, their plastic behavior governed by historydependent, piecewise-linear yield functions and fully coupled hardening rules. Elastic moduli are required to be positive-definite and plastic moduli nonneg...