At present, automotive industry is required to improve fuel economy performance due to high oil price and the intensification of environmental regulation. As a result, a study on maintaining the performance of structure and reducing weight is one of the hottest issues of automakers. The research and development of power train has a limit in satisfying these requirements. So, automakers actively carry out studies of reducing the weight of automotive body and component parts. Carbon fiber reinforced composite having high specific strength and specific stiffness properties is excellent in weight reduction effect in the aspect of increasing vehicle fuel economy and efficiency. Accordingly, a study is actively made on its application to vehicle body structure. And a real product was also launched. Recently, owing to the development of composite manufacturing technology, it became possible to manufacture composite parts of various shapes. And it became necessary to design a product where the conformity of structural properties, vehicle''s required properties, was verified in advance in manufacturing composite frame and a vehicle''s outer panel which was directly connected to passengers'' safety.
In this paper, a vehicle fastener made of isotropic material was tested and analytically verified. And on the basis of the verified results, the optimal design of a composite vehicle door was carried out. Hypermesh was used for finite element modeling. And optimal design composed of topology optimization, shape optimization, strength analysis, size optimization and stacking sequence optimization was carried out by using Optistruct.
First of all, an optimization was carried out, passing through the process of classification and calculation of load according to driving environment and application of friction force occurring at the interface when a trailer was fastened to a truck for the optimal design of large truck connector of isotropic material. The direction and magnitude of load due to roll, pitch and yaw phenomena occurring when a truck traveled was calculated. And resultant values were applied to 5th wheel coupler. And on the basis of this, this study presented a model that had a reinforced structure of a type different from conventional model, and satisfied the required performance. And the reliability of optimization regarding isotropic materials was verified analytically and experimentally by carrying out a durability test and road test through the manufacture of real structure. On the basis of these verification results, the optimal design of vehicle side door using composite was carried out. In order to set the boundary conditions for finite element analysis, EuroNCAP Side Impact Test Protocol was applied. And optimal design was carried out. This study presented a standardized finite element model of vehicle side door using composite, passing through free-size optimization, size optimization and stacking sequence optimization phases.