The Calculating System Of Accident Vehicle Body Plastic Deformation Based On The Finite Element Method

With the continuous growth of car ownership, road traffic accidents have become a major social problem,the using of computer technology to deal with road traffic accidents has become a trend, and achieved good results. After the accident, the most intuitive manifestation is the plastic deformation of the body, analyzing and calculating the plastic deformation of the body can provide useful reference information for the Traffic Accidents Department. At present, the commonly used method of calculating plastic deformation of the accident vehicle’s body is calculating according to the collision stiffness, this method requires a large amount of the actual vehicle crash tests to get the vehicle collide stiffness in different directions. It requires a lot of manpower, material and financial resources, and our country did not establish the database of the car crash stiffness. So researching a universal adaptability calculation method of plastic deformation of a vehicle body has important engineering significance.By analyzing the deformation process of vehicle shell structure when vehicle has collision, the dissertation establish the plastic deformation computing system of accident vehicle body’s shell structure based on VC ++ platform and finite element theory. In this paper, the complex plastic deformation of vehicle body’s shell structure is divided into several small elements according to the principles of finite element meshing theory. By using each unit’s mechanical parameters to establish the continuum force balance equation, then calculate nodal forces and calculate the equivalent load and equivalent plastic deformation energy. Finally, completes the test of the effectiveness of the system.Through studying the plastic shell structure of body, constructs the plate element, using the flaps that assembled by plate element to instead of the shell structure, according to the plastic deformation’s stress and strain relationship, using increment method to establish the plate element’s element stiffness model in the plane stress state and bending torsion stress state.In-depth study features of the structure overall stiffness matrix, the dissertation designs the one-dimensional compression storage method of the structure overall stiffness matrix. For the structural form and solving process of nodal force equilibrium equations, the dissertation propose the forward proposed solution method of node force based on one-dimensional storage of overall stiffness matrix.Finally, the dissertation develops the accident vehicle body’s plastic deformation computing system. Based on VC ++ platform, the system establishes processing module, nodal force calculation module and post-processing module. The processing module includes node coding,unit coding and generating nodal displacement. The nodal force calculation module includes plate stress state calculation and bending torsion stress state calculation. The post-processing module establishes the part of equivalent load calculation and equivalent plastic deformation energy calculation for the computing characteristics of load calculation and plastic deformation energy calculation. At last, the system effectiveness test is completed.