Characterisation of Sheet Metal Formability - A Review and New Approaches

This paper gives a historical overview of techniques of characterising sheet metal material behaviour. First it reviews the evolution of yield criteria in the past, hardening laws and failure-prediction methods based on comprehensive time tables. After that, it demonstrates some shortcomings of today's material characterisation such as the impact of strain induced texture changes on material characterisation. Then the lecture shows further approaches to a more adequate description of material behaviour with regard to biaxial stress conditions and a new failure criterion for sheet metal bending processes, the so called Bending Limit Curve (BLC) concept. It also presents a new testing method for pure shear and simultaneous tension and shear loading as well as further approaches to understand material behaviour.