LAUSR

Abstract An unconventional destructive method for quantitative assessment of fatigue damage accumulation in the stress concentration zone is proposed and verified. Damage accumulation in strain gradient area is reached by preliminary push-pull loading of plane specimens with open holes. Narrow notches, emanating from the hole edge at different stages of low-cycle fatigue, serve to manifest a damage degree. These notches are inserted under constant external load. Deformation response to local material removing is measured by electronic speckle pattern interferometry (ESPI) in terms of in-plane displacement components. It is shown that normalized values of the notch mouth open displacement (NMOD), the stress intensity factor (SIF) and the T-stress can reliably be used as current damage parameter. Numerical integration of curves, describing an evolution of fracture mechanics parameters, produces the damage accumulation function in an explicit form. It is established that all three fracture mechanics parameters give close results.