Experimental and numerical study on effect of forming process on low‐cycle fatigue behaviour of high‐strength steel

Application of high‐strength steel on different structural components is becoming more attractive. In spite of their great advantages of high yield strength, the use of these steel grades faces some important challenges as well. There are many formed steel components of different structures that are subjected to fatigue loading conditions. The main objective of the present study is to investigate the effect of pre‐bending process of high‐strength steel subjected to low‐cycle fatigue loading conditions. For this purpose, a new test set‐up has been designed to take into consideration the effect of pre‐bending process when the fatigue load is applied. To detect fatigue crack initiation onset, lock‐in thermography technique is used to monitor the incremental temperature variation during fatigue cycling. Furthermore, to estimate fatigue lifetime of the formed fatigue sample, continuum damage mechanics approach is applied by means of numerical modelling.