Residual Stress Analysis of Ceramic Coating by Laser Ablation and Digital Holography

In this paper, a method for residual stress analysis of ceramic coatings by applying a laser for quasi non-destructive material removal and measuring the 3D displacement around the machined area by means of high-resolution digital holography is described. The residual stresses are retrieved by numerical calculations using the finite element method (FEM) from the measured 3D displacements, the profile of the machined hole and the material parameters of the coating and substrate. Experimental results on thermal spray coatings together with discussion of the difficulties, work in progress, potential of the method, and comparative measurements by the hole-drilling method are presented.