Optimized butterfly specimen for the fracture testing of sheet materials under combined normal and shear loading

摘要: Abstract The present paper is concerned with multi-axial ductile fracture experiments on sheet metals. Different stress-states are achieved within a flat specimen by applying different combinations of normal and transverse loads to the boundaries. geometry optimized such that initiates remote from free Fracture carried out TRIP780 steel for four loading conditions, varying pure shear plane strain tension. Hybrid experimental–numerical analyses performed determine stress fields gage section. results show localization cannot be avoided prior onset fracture. Through-thickness necking prevails under tension-dominated while deformation localizes along band crossing entire section shear-dominated loading. Both experimental simulation demonstrate proposed testing method very sensitive imperfections in machining. paths determined terms triaxiality, Lode angle parameter equivalent plastic strain. data indicates relationship between triaxiality at not unique.