Measurement of two-dimensional residual stress in nanocrystalline superelastic NiTi fabricated with pre-strain laser shock peening

Abstract

The measurement of residual stress is a challenging issue in industrial fields. In this work, focused ion beam (FIB) and digital image correlation (DIC) are combined together to measure the two-dimensional residual stress in nanocrystalline NiTi plates processed with pre-strain laser shock peening (LSP). A four-point bending experiment verifies the accuracy of this measurement method. The pre-strain LSP-treated surfaces are found to have significant compressive residual stress along the pre-strain direction and tensile residual stress along the vertical to pre-strain direction, which verifies pre-strain LSP as an efficient approach to create gradient residual stress layers in nanocrystalline NiTi plates. The FIB-DIC method has also proven to be an attractive tool to measure the two-dimensional residual stress in phase transition nanocrystalline materials.

In memory of Prof. Hui-Hui Dai

“…Prusa et al [12] investigate the pure bending of an elastic prismatic beam where the material parameters are density dependent and a semi-analytical solution is obtained to assess the impact of density-dependent material parameters. Yan et al [13] discuss how focused ion beam and digital image correlation can be combined together to provide an attractive tool for measuring the two-dimensional residual stress in nanocrystalline NiTi plates processed with pre-strain laser shock peening and phase transition nanocrystalline materials.…”