Residual stress/strain evolution due to low-cycle fatigue by removing local material volume and optical interferometric data

摘要

Three experimental methods, based on optical interferometric measurements of deformation response to local material removing, have been implemented for residual stresses determination. Two first techniques are employed to characterize initial residual stress values and their evolution near welded joints of aluminium plates under low-cycle fatigue. The hole-drilling method gives high-accurate dependencies between residual stress components and number of cycles. The second approach comprises cracks modelling by narrow notches to describe residual stress distributions in more wide spatial range near the weld. The results demonstrate residual stress evolution is of complex character and cannot be uniquely qualified as a gradual relaxation. Besides, the secondary hole drilling method is developed and used as a fast and reliable tool to quantify the redistribution of residual strains near cold-expanded holes due to low-cycle fatigue. Dependencies of circumferential residual strains along the secondary hole edge versus number of cycles are constructed.