Abstract:

 A conceptual design process of vehicle body structure was presented with a simplified space frame model being established since conceptual design is important for vehicle body design. A stiffness chain model of vehicle body was established by using a semi-rigid beam and transfer matrix method. The strain energy and strain energy density of the optimized beam element were analyzed by solving the optimization model with constrains only including the static and dynamic performance. The coefficient of variation was introduced as the constraint index to coordinate and optimize the utilization and distribution of materials under multiple working conditions. The design method considered the vehicle body semi-rigid beam stiffness chain and the strain energy factor. Body lightweight was taken as the objective function, and the vehicle body static stiffness, natural frequency, and the uniformity of the strain energy density at each working condition were taken as constraints for optimization. The genetic algorithm was used to solve the optimization problems and determine the main crosssection parameters. The results of the design method were compared with the simulation results of benchmark vehicle. The results show that the uniformity of strain energy density can improve the utility of the material and the performance of the vehicle body. Therefore, the design method is feasible. Key

Key words:  vehicle body conceptual design ,  semi-rigid beam stiffness chain model , strain energy , strain energy density , structure optimization