Modelling of Stress Evolution and Its Effect on Formability in Tension Under Cyclic Bending Plus Compression

This chapter delves into the modeling of stress evolution and its effect on formability in tension under cyclic bending and compression, with a focus on incremental sheet forming processes. It introduces the Tension under Cyclic Bending (TCB) and Tension under Cyclic Bending and Compression (TCBC) tests, highlighting their similarities to SPIF and DSIF processes. The study presents a detailed analytical model to capture local stress states, revealing the relationship between stresses in the tension and through-thickness directions. The model also investigates strain evolution in bending and unbending processes, shedding light on the reduced forming forces and stress distribution. Through comparative assessments using a damage function of stress triaxiality and plastic strain rate, the chapter provides insights into the correlation between TCB, TCBC, and SPIF, DSIF processes. The results are validated against FE simulations, emphasizing the importance of through-thickness stress and strain discrepancies in fracture initiation. The chapter concludes by highlighting the limitations of the analytical model and suggesting areas for further investigation to enhance the accuracy of predictions.