Strain gradient and wavelet interpretation of size effects in yield and strength

Document Type

Conference Proceeding

Publication Date



The problem of yield stress and ultimate strength dependence on the specimen size is considered. This dependence, in otherwise geometrically similar specimens, is herein interpreted on the basis of gradient plasticity and wavelet analysis which introduce an internal length scale in the stress vs. strain relation. In particular, gradient plasticity within a simple strength of materials approach and wavelets within a simple scale-dependent constitutive equations approach, are used to derive expressions for the yield stress and the ultimate strength of solid bars subjected to torsion and bending. It is shown that these expressions depend on the size of the specimen. When the dimensions of the specimen become comparable to the internal length scale, size effects become important, while for larger specimens such dependence becomes negligible. Comparisons of the theoretical predictions to available experimental data are given. © 2002 Elsevier Science Ltd. All rights reserved.

Publication Title

Mechanics of Materials