Residual stresses near cold-expanded hole at different stages of highcycle fatigue by crack compliance data

摘要

Experimental method for a characterization of high-cycle fatigueevolution of residual stress near cold-expanded hole is developed andimplemented. The technique is based on simultaneous measurements ofdeformation response to narrow notch, inserted in residual stress field, onopposite specimen’s faces by electronic speckle-pattern interferometry(ESPI). Two-side measurements of through notch opening displacements areperformed when a single notch, emanating from cold-expanded hole edge, isinserted. The transition from in-plane displacement component to residualstress intensity factor (SIF) values follows from the relationships of modifiedversion of the crack compliance method. The approach provides a differencein residual stress values referred to mandrel entrance and exit surface. Notchesare inserted at different stages of high-cycle fatigue without applying externalload. The results obtained describe fine nuances of residual stress evolution,which cannot be considered as monotonic relaxation. .