Tailoring of residual stresses by specific use of defined prestress during laser shock peening

摘要

The aim of the present study is to tailor laser shock peening-induced residual stresses by applying defined prestress. For this purpose, elastic prestress is introduced during laser shock peening application and subsequently released. The influence of prestress on the resulting residual stresses is investigated experimentally by a four-point bending device that allows prestressing of the specimen during laser shock peening. Furthermore, a semi-analytical model of laser shock peening, extended by a contribution accounting for the prestress, is used to determine the prestress-residual stress relationship. A linear relation between prestress and compressive residual stress is found when the resulting compressive residual stresses are in the range of 20 % - 100 % of the yield strength. Generally, tensile prestress leads to a higher magnitude and penetration depth of resulting compressive residual stress after laser shock peening. As a proof of concept, prestress was used to alter a nonequibiaxial residual stress profile into an equibiaxial one, demonstrating the applicability of prestress as an effective tool for residual stress design.