Creep‐fatigue behavior of thin‐walled plate with holes: Stress state characterization and life estimation

Abstract This paper proposes a novel creep‐fatigue life estimation method considering the effect of non‐uniform stress state, through the comprehensively experimental and numerical investigation. Conventional and digital image correlation (DIC) based in‐situ creep‐fatigue tests were performed on thin‐walled plates with various types of holes at 850°C. DIC measurements and scanning electron microscope (SEM) analysis show that tensile stress plays the dominant role in the creep‐fatigue failure of plate with holes, and the crack initiated at the maximum stress position of the end hole. An equivalent stress was defined to describe the complex stress state between the adjacent holes. The stress factor was proposed to account for the holes‐related stress concentration and multi‐axial stress state. Moreover, a novel weight function was proposed to assess the damage contribution of non‐uniform stress in the damage zone. Creep‐fatigue life model was developed by introducing this proposed weight function, and was validated based on test data.