GPA Combined with the Hole‐Drilling Method Applied for Curved Surface Strain Measurement

Abstract: This paper describes three methods that were modified and combined to investigate the residual strain of a curved surface. First, the traditional grating transfer method previously only applied to a flat surface was extended to a curved surface using a new fabrication and transition approach. Second, the GPA method previously only applied in the nanoscopic field was extended to the macroscopic field. Third, both of the above methods were combined with the hole‐drilling method to obtain deformation information on the plane analysing grating. The data obtained were used to analyse the in‐plane residual strain by the GPA method, and an algorithm that can use the plane analysing grating data was used to calculate the curved specimen grating deformation. The feasibility and reliability of these methods were verified by using them to measure and analyse the residual strain of a welded joint on a stainless steel tube.