LASER WELD PROPERTIES IN THE FINITE ELEMENT ANALYSIS OF PRESSFORMED TAILORED BLANKS

摘要

To compare the formability of laser welded tailored blanks (LWTBs) with that of unwelded samples, finite element analysis (FEA) of small scale forming limit tests and modified stretch draw (MSD) tests has been conducted on different strength/thickness laser welded high strength steels, incorporating the weld material properties. Using an alternative strain analysis technique, which was shown to be 20% more accurate than the standard technique, it has been demonstrated experimentally that the forming limit curve (FLC) of a dissimilar strength/thickness LWTB, with the weld orientation transverse to the major strain axis, can be estimated using the FLC of the weaker/thinner parent material. The experimental work has been reinforced by FEA models. Close correlation between FEA and experiment has also been achieved for MSD tests involving different strength/thickness LWTBs. A reduction in the ratio of (0.2% proof strength x thickness), for the chosen parent steels, resulted in a considerable increase in the formability performance of the LWTB. These models can now be used to accurately predict the formability of LWTBs comprising other steels and different laser weld parameters, with a dramatic reduction in the required amount of practical tests.