Deformation mechanisms and fracture in tension under cyclic bending plus compression, single point and double-sided incremental sheet forming processes

This study investigates the deformation and fracture mechanisms of two testing methods, tension under cyclic bending (TCB) plus compression (TCBC) their relationship to single point (SPIF) double-sided (DSIF) incremental sheet forming processes. Experimental tests were carried out by using a bespoke TCBC test rig DSIF machine with grade 1 pure Ti samples. The results show elongation-to-fracture has high relevance depth compression, which leads detailed investigation stress strain evolutions in local region finite element (FE) method. A new Gurson-Tvergaard-Needleman (GTN) model is proposed modified shear damage mechanism utilising experimental loci calibrate Lode angle effect low triaxiality. It found reverse-bending stages correspond different states significantly affect occurrence TCB, SPIF, For first time, paths plane triaxiality parameter are used reveal transition modes from equi-biaxial SPIF DSIF, as compared TCB TCBC. Using GTN model, simulation gives accurate predictions TCBC, an error less than 8% comparison results. Although there distinction between uniaxial deformations, concludes that provide insight into formability improvement represent intrinsic processes, ongoing research question, drawn considerable attention recent years.