Inversion of residual stress

A technique for inverting residual stress based on a theory of acoustoelast icity is presented. A general incremental constitutive relation is first de rived for a pre-stressed material subjected to an additional infinitesimal elastic deformation. The theory is then employed on using ultrasonic means to evaluate residual stresses of residually stressed materials. The residua l stresses are assumed to be homogeneous in materials as usual. The only ma jor assumption in this formulation is that the additional deformations caus ed by ultrasonic evaluating process are infinitesimal and elastic. No assum ption on the origin of residual stresses is needed, nor the assumption on t he possible existence of "natural state" of the materials. Successful inver sion of residual stresses are demonstrated through a preliminary numerical experiment.