Research On Optimization Design Of Composite Automotive Bumper Beam With Variable Thickness

The research of automotive body crashworthiness and lightweight has a greatsignificance for automotive industry. It is an effective way for the lightweight design ofautomotive with the application of the composite in the automotive bumper beam. Withthe improvement of the performance of composite, it will be applied more broadly.Based on the requirements of regulation GB17354-1998, the author did the research onthe application of carbon fiber/epoxy composite in the automotive bumper beam by thispaper, which can be described as follow:First of all, the finite element models of two dissimilar materials of the automotivebumper beam under the low-speed impact is established in accordance with therequirements of regulation GB17354-1998. The crashworthiness of the two dissimilarmaterials of the automotive bumper beam is comparative analysed from the aspects ofmaterial failure, the intrusion volume of pendulum, cross-section force of the crash boxand specific energy absorption of the bumper system.Secondly, in accordance with the mechanical behavior of the automotive bumperbeam and the intrusion volume of pendulum under the two conditions of low-velocityangulate and frontal impact, the automotive bumper beam is designed with differentthickness in different areas. Moreover, the thickness and the length of the thickened areaare selected as variables, then the Kriging models for the section force of the crash boxand the mass of the automotive bumper beam are constructed, respectively. The last,NSGA-II is applied to search the global optimal designs.Finally, since all the possibilities of multi-working conditions are considered in theprocess of variable thickness optimization design. Through transforming the possibilitiesof various multi-working conditions to the weighting factors of the optimization objects,the cross-section force and specific energy absorption are changed to weightedcross-section force and weighted specific energy absorption. The Kriging models of theweighted cross-section force and weighted specific energy absorption are constructed tobe solved using genetic algorithm.The results indicate that the carbon fiber/epoxy composite automotive bumper beamsatisfies the requirements of low-speed impact standard, and furthermore, thecrashworthiness of the composite automotive bumper beam with the variable thicknessdesign is optimized without adding mass under the two conditions of low-velocity impact. In addition, the optimization design of variable thickness based onmulti-working conditions can further improve the crashworthiness of the compositeautomotive bumper beam, and the result also has a guiding significance in the realsituation.