Laser Forming of Varying Thickness Plate—Part II: Process Synthesis

Laser forming (LF) is a non-traditional forming process that does not require hard tooling or external forces and, hence, may dramatically increase process flexibility and reduce the cost of forming. While extensive progress has been made in analyzing and predicting the deformation given a set of process parameters, few attempts have been made to determine the laser scanning paths and laser heat conditions given a desired shape. This paper presents a strain-based strategy for laser forming process design for thin plates with varying thickness, which is utilized in determining the scanning paths and the proper heating conditions. For varying thickness plates, both the in-plane membrane strain and the bending strain need to be accounted for in process design. Compared with uniform thickness plate, the required bending strain varies with not only the shape curvature but also with the plate thickness. The scanning paths are determined by considering the different weight of bending strain and in-plane strain. A thickness-dependent database is established by LF finite element analysis simulation, and the heating conditions are determined by matching the ratio of bending strain to in-plane strain between the required values and the laser forming values found in the database. The approach is validated by numerical simulation and experiments using several typical shapes.