NUMERICAL SIMULATION ON DOUBLY CURVED SHIP HULL-THICK PLATE FORMING WITH MULTI-PRESS HEAD

摘要

Multi-point forming or reconfigurable die forming is an attractive technology for small number production for shipbuilding and aerospace. But there are dimple and wrinkling defects. We proposed a novel method to suppress the defects, which is named metal sheet forming mechanism with rotary square press head and non-pair press technology. In this paper, numerical simulation on the forming process of doubly curved ship hull plate is presented based on Ansys LS/DYNA finite element software. The forming system mainly consists of a reconfigurable lower die and a controlled system. The reconfigurable lower die has 15~*15=225 element punches with rotary square press heads. Every punch is 58mm~*58mm in section, its height is decided by software or calculated, and is adjusted by control system automatically. So the simulation model is built automatically by the height matrix. The dynamic explicit finite element method is chosen to implement the simulation of forming process. The bilinear isotropic hardening material model is used to describe the plate. The contact between the press head and sheet is regarded as rigid. The typical two shapes of doubly sheet, pillow-type and saddle-type plate simulations are carried out. The simulation results show that (1) the surface of square press head will rotate according to the shape of forming surface during the stamping process, which accords with the actual forming process. (2) the forming plate is smooth and the distributions of stress and strain on the sheet is uniform, which will not lead to dimple and wrinkling.