Absorption Characteristics Analysis And The Experimental Research Of The Car Bumper

Security, energy saving and environmental protection, which are not only theexpectations from car consumers, but also the missions for the car designers, have becomethe three themes of the development of automobile industry. As an effective measure tosave energy and reduce emissions，the lightweight design has been universally recognizedand highly valued. Automobile bumper, located in the front of the car, is the first contactsite in front collision accident and therefore plays an important role in reducingpedestrians’ injuries in pedestrian-vehicle collision and decreasing the damage to thevehicles in vehicle-vehicle collision. Therefore, it is of great significance to study theabsorption characteristics of automobile bumper, to improve the absorption characteristics,to realize the lightweight design and to reduce the quality of parts on the premise ofmeeting the performance requirements.The paper makes a comparative study on the energy absorption characteristics of thesteel bumper and the aluminum bumper by the combination of the simulation analysis andthe experimental research, and the combination of the material replacement and the methodof structural optimization design, and achieves a lightweight design. The research workinvolves several parts as follows:Firstly, the paper builds bumper geometry model in CATIA according to the scanimage obtained by scanner and the finite element model in the pre-processing softwareHypermesh, makes simulation analysis on the crashworthiness of steel bumper inlow-speed frontal collision，offset collision and static extrusion based on LS-DYNA, andconducts the corresponding experimental research. The intrusion is more than the allowedmaximum in low-speed100%frontal collision, the bumper should be redesigned.Secondly, the paper studies material replacement in steel bumper, builds aluminumalloy bumper model according to the boundary size of steel bumper and makes thesimulation analysis and experimental research on the low-speed crashworthiness of thealuminum alloy bumper. As the test results are in good agreement with the simulationresults, the correctness of the finite element model of aluminum bumper is verified.6101aluminum alloy bumper has much better low-speed crashworthiness, higher energyabsorption capacity and specific energy absorption.Thirdly, the paper builds a topology optimization model of bumper beam, carries out topology optimization by using Optistruct software and makes size optimization of the wallthickness of topologized new structure to get a new beam structure. The chapter also makesa comparative analysis of the impact on energy absorption characteristics caused byenergy-absorbing box cross-sectional shapes with the help of the experimental designmethod to get the best cross-sectional shape, studies the impact on the energy absorptioncharacteristics by the wall thickness and the location of the V-induced.Lastly, the paper matches the new6101aluminum alloy bumper and the stiffness ofthe front longitudinal beam to meet the design requirements of the step increment of thestructural stiffness. With the material replacement and the improved design, the newaluminum bumper has a good performance on the simulation experiments includinglow-speed collision. three static pressure, completely crushing crash, and its intrusion ofthe beam is lower than the allowed maximum in all these experiments. Meanwhile, thestiffness of the bumper is improved with the increase of the static crushing force peak.Compared with steel bumper, with the material replacement and the optimizing structure ofthe new aluminum bumper, its energy-absorbing capacity is increased by211.9%, thequality lowered by46.2%, the specific energy absorption increased by580%, and theenergy-absorbing characteristics is greatly improved as well as the lightweighting effect.