Accurate Acquisition Of Strain And Analytical Method Of Out-of-Plane Strain For Ship Hull Curved Plate

The shell of ship is made up by many complex curved plates.The automatic forming of the ship hull curved plate has always been an urgent problem to be solved in the shipbuilding industry.The key to solving this problem lies in the development of automated forming equipment for ship hull curved plates.The premise for the development of automated forming equipment that meets the requirements is to clarify the relationship between the target forming sheet and the processing method,and the strain distribution is used as the medium for the initial flat sheet deformation as the target curved plate,which is essential for determining the processing technology.In order to ensure the continuity of the process,the efficiency of the strain distribution calculation is also very important,Moreover,most of the ship hull curved plates belong to medium-thick plates,and its out-of-plane strain dominates the forming process,so the fast and accurate calculation of the out-of-plane strain is particularly important.The background of this paper is the ship hull curved plate forming,exploring calculation method of the out-of-plane strain that effectively improves the computational efficiency under the premise of ens uring the calculation accuracy.The large-deformation elastic FEM is applied to simulate the process of unfolding the curved plate to obtain the strain distribution.Aiming at the special and important shell shape of the spherical shell,the influence factors of strain distribution and the influence of strain composition on the forming were studied.Using the double triangular base fitting function to achieve the fitting of the discrete surface,based on the simple and effective mathematical expression of the discrete surface,use analytical method based on nonlinear kinematics analysis to quickly obtain the out-of-plane strain that curved plates forming requires.On this basis,a calculation program for the out-of-plane strain of the ship hull curved plate is designed.From the input of the discrete curved p late data to the output of the out-of-plane strain distribution map,the flow calculation of the out-of-plane strain distribution can effectively improve the calculation efficiency while ensuring the calculation accuracy.