Residual stress analysis of hull plate in multi-point forming

Hull structures and offshore structures are composed of curved thick plates. The flame bending has traditionally been used to produce such curved plates. However, it is difficult to accurately achieve the desired shape due to the unmanageable process and residual deformation. Multi-point forming mechanism with square press heads is a new forming process for 3D ship hull plate. However, spring-back and residual stress are the major problems in cold-forming process. The present researches focus on the spring-back but ignore the effect of residual stress in cold-forming. This paper uses both theoretical derivation method and numerical research to analyze the residual stress distribution in the multi-point forming. The maximum residual stresses calculated from the theoretical model agree well with the numerical results.