| With the rapid development of Chinese automobile industry, the number of civil vehicleownership has grown very much. At same time, the number of traffic accident happened inchina for every year has increased constantly. Several malignant accidents caused a strongfocus on by national people. Under the current situation in our country, the fundamentalcause of car accidents would inevitably exist for a long time in the foreseeable future.Therefore, road traffic accident has harm to national security. It was urgent that safety studyof vehicle in order to protect drivers and passengers.This research was based on the key project of national nature fund “the basic theory,calculation methods and key technology of Stamping and die design”, National outstandingyouth fund projects “Stamping die CAD based on KBE expert system theory and thepolymer plate shape theory and the calculation method for the research” and the majorproject of national automotive electronics industry. This research was focus on the keytechnology of passive safety and pedestrian protection. The main content and researchresults were followed as:1) A design and optimization method of two-way parameterized was proposed. Thismethod could bring advantage of design optimization whose main characteristics wasrealized parameterization of CAD and CAE. In this design optimization method, the result ofCAE analysis would been feedback to the CAD processing. The design optimization resultof car body parts was displayed in real time and could realize the function that the CAEanalysis guided the structure design early stage. This method could be used design ofauto-body panels not only part but also as a whole. This method could shorten the cycle ofparts design and would be the developing trend of future in the field of auto-body design. Inorder to display the function of the optimization method of two-way parameterize, using thecrashworthiness design optimization of front beam as example, Parameterized finite elementmodel of the vehicle body frame structure was constructed. With the key parameters ofvehicle body frame structure as design variable, the lightweight of the structure as object, thecrashworthiness of front impact as constraint, the design optimization model was constructed.Using the results of design optimization, the design parameters were obtained that they meet the requirements of crashworthiness and lightweight. According the obtained variables, thereal vehicle model was manufacture, and was been validation.2) Firstly, the pedestrian leg protection technology was researched with the designprocess of bumper as example. A new style bumper structure was designed according theactual usage of current bumper. In this new bumper, the filled foam was instead by a newenergy absorption buffer plate. This new style bumper could absorb energy fully. Secondly, anew impact finite element model was proposed based on the response surface model. Theimpact finite element model was validated by simulation and experiment. This finite elementmodel met the regulations of Euro-NCAP. Thirdly, the design optimization of absorb panelof bumper was carried out. With full factors design of experiment method, the combinationof different material property and thickness of panel was simulated. After the analysis ofresults, the final design scheme was determinate. Finally, based on the development processof absorb panel of bumper, a method of technological design optimization process of bumperwas proposed. This method could be referenced by the auto industry.3) The research about pedestrian head protection of auto-body engine hood was carriedout. Based on the theory of multi rigid body, the influence that pedestrian movementcharacteristics to its own protection. The pedestrian parameters based on Chinesecharacteristic were obtained. Through the impact examples, the injury characteristic ofpedestrian in impact between pedestrian and vehicle was researched. The distributionregularities of different influence factors was obtained. Through analysis of the feature ofengine hood structure and impact results, the distribution regularities of HIC value on theengine hood was obtained. It was been proved that HIC value was directly proportional tothe distance between engine hood impact position and second impact position. This relationwas same with material yield strength of second impact position. The correlation empiricalformula was summarized. This formula could be used as the basis of rapidly predictiondangerous position on the engine hood for auto-body designer. According this correlationformula, the trend diagram of relative HIC value could be calculated and the most dangerousposition in each domain could be obtained, before the impact simulation and experiment.These could be referenced by impact simulation and experiment later. Finally, the searchmost dangerous position method was validated by experiment and the result indicated thatthis method was reliable.4) The B pillar was the important part which guaranteed the side crashworthiness ofauto-body. In order to guarantee the crashworthiness and lightweight of B pillar at same time, a design optimization method was proposed. This method could be referenced by lightweightdesign in auto-body. The sub model was constructed using the motion of whole vehicleimpact process as the boundary conditions. Through the comparative analysis of sub andwhole model, the sub model could be used as the surrogate model of the whole. With the submodel, the time of simulation could be decreased. In the sub model, the original outer panelof B pillar was replaced by hot-formed panel, and the original inner reinforcing panel of Bpillar was no using. The design optimization model was constructed using software Optimus.The thickness of outer and inner panels was set as design variable. Through the designoptimization model, the thickness of panel that met the engineering needing was obtained.Comparing with the original panel structure, the weight of new structure decreased4.65kg.Then, the results of optimization were set back the whole model, and validation test wascarried out. The result of validation proved that the proposed design optimization methodwas feasible. |
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