Laurent Bernard Chappuis

A Path-Independent Forming Limit Criterion for Stamping Simulations

Forming Limit Diagram (FLD) has been proved to be a powerful tool for assessing necking failures in sheet metal forming analysis for majority of stamping operations over the last three decades. However, experimental evidence and theoretical analysis suggest that its applications are limited to linear or almost linear strain paths during its deformation history. Abrupt changes or even gradual deviations from linear strain‐paths will shift forming limit curves from their original values, a situation that occurs in vast majority of sequential stamping operations such as where the drawing process is followed by flanging and re‐strike processes. Various forming limit models have been put forward recently to provide remedies for the problem, noticeably stress‐based and strain gradient‐based forming limit criteria. This study presents an alternative path‐independent forming limit criterion. Instead of traditional Forming Limit Diagrams (FLD) which are constructed in terms of major ‐ minor principal strains throu...