Optimization Matching Of Different Metal Sheets In Steel-aluminum Hybrid Car Body Structural Components

With the development of automobile industry, every kind of light materials likealuminum alloy and magnesium alloy are put into car manufacturing co ntinually. This trendalso becomes a development direction of vital importance. Car body light weight design isone of the most effective methods to improve fuel economy and reduce emission. Comparingto the traditional steel structure car body, the steel-aluminum hybrid car body are consisted ofadvanced high strength steel(AHSS) and aluminum alloy. This kind of mode will take theadvantage of superiorities existing in the AHSS on the facts of strength and price, also thecharacters of aluminum alloy in energy absorbing and weight reducing will be taken intoaccount in order to achieve the crashworthiness design of lightweight car body.When developing steel-aluminum hybrid car body structures, its crashworthiness designwill face the problem of matching materials concerning strength grade and thickness. Take athin-walled structure from the steel-aluminum hybrid car body as an example ofcrashworthiness design. So a new type of steel–aluminum hybrid structure was presented,where aluminum alloy was used for the front part and AHSS for the back. By consideringmaterial types and the sheet thickness as variables, the theoretical models of multi-objectiveoptimization for its lightweight and crashworthiness were established. In order to solve thecrashworthiness problem, their feasibility and suitability were emphatically investigated byusing polynomial, Kriging and radial basis function (RBF) metamodels. The result shows thatRBF is more suitable to be adopted as a metamodel to solve the problem about material typesand sheet thickness. Comparing to the traditional pure steel structure, the usage ofsteel–aluminum hybrid materials can significantly improve the crashworthiness andlightweight of front rails. It also provides a reference for the development of furthersteel-aluminum hybrid car body structures.Another problem exists in the development of steel–aluminum combined structure is theconnection between dissimilar materials. The steel sheet SPFC590and aluminum sheetA5052-H34with thicknesses of both1.5mm were chosen as the research objects, and thenumerical simulation and experimental research were carried out to study the join feasibilityby using mechanical clinching. With the right results from both two sides, the applicationrange of mechanical clinching will be expanded. It also provides a base for the optimizationof clinching joints on the following steps.Focused on the place order of the sheets, strength grade of materials and sheets thickness, the performance of clinching joints are researched. Some rules for the place order of sheetsare concluded. By considering material types and the sheet thickness as variables, theMulti-objective optimization method are implemented on the optimization job of theclinching joints performance. After the optimization, these clinching joints with highmechanical strength and lightweight are acquired.