Effect of stress concentration at weld toes on combined high and low cycle fatigue of EH36 steel welded joints

In order to study the effect of stress concentration at the weld toes on combined high and low cycle fatigue(CCF) of EH36 steel welded joints for ship structure, CCF tests were carried out on EH36 steel double-sided butt joints with 20 mm thick and different weld profiles. The results show the extent of reduction in joint life subjected to CCF increased with increasing high stress ratio of high cycle fatigue; Based on the digital image correlation method, the higher the stress concentration coefficient at the weld toes, the lower the CCF life of the joints. The extent of reduction increased with increasing stress ratio of high cycle fatigue. Validation of the models based on experimental data shows that joints with high stress concentration coefficient have lower fatigue life and increased dispersion of life prediction results; The Palmgren-Miner model and Zhu model do not fully consider the CCF damage effect, which leads to dangerous prediction results of CCF life. The modified Zhu model fully considers the influence of CCF. There are few prediction data points that the predicted life is higher than the actual life.The prediction results are relatively safer. The dispersion and the error are smaller.