A Study On The Crashworthiness Of Passenger Car In Low-speed Front Impact

In an impact of passenger vehicle to a barrier at a low-speed of 15 km/h, theremay be no injuries for occupants. Some parts of vehicle can be destroyed. Theconsumers have to change or repair these parts. It is an economic burden for consumersand insurance companies. Governments have therfore introduced legislation toimprove the crashworthiness of the vehicle front bumper system. Now many countrieshave developed low-speed impact regulations. Insurance companies estimate thecrashwortheness perfomace of a car considered the result from the low-speed impact.Also the consumers can buy cars which meet the requirement of the legislation. So it isimportant to improve the performance of vehicle front bumper system at low-speedimpact and reduce the upkeep costs.The aim of present study is to investigate the difference between Nationallegislation and and insurance standards in front bumper impact test at low-speed, andto optimize crashworthiness in the design of automotive front parts.For the aim mentioned above, the three regulations were introduced in this study,including the Federal Motor Vehicle Safety Standards (FMVSS) Part 581, the criterionof vehicle's front and rear protector GB 17354-1998, Research Council for AutomobileRepairs (RCAR) and IIHS-Test (Insurance Institute for Highway Safety). In order tostudy on vehicle low-speed crashworthiness, a finite element model of car was adapted.A car was evaluated according to the three regulations for front crashworthiness. Thiscurrent paper compared the influence of pendulum's height on the bumper, theimpacted energy and collision parts damaged in collision and different design purposeof high-speed collisions and low-speed collisions. Advices were provided to improvethe crashworthiness of front bumper system at the low-speed impact.In order to study the sled front impact test, a finite element model of sled wasadapted, also. A low-speed impact model was constructed according to the RCAR testusing the sled model. Firstly, the parameters of the structure of the crash-box wereselected. Then Orthogonal Arrays design of experiments was used to generate the testsample points. A global optimization of the structure was preformed based on theKriging approximation model. The optimized crash-box can absorb sufficient energy.The section force at crash-box was decreased to meet the requirement of the designstandard.The results from this study indicated that the speed and impact energy ofpendulum is low in test. In the test, the bumper and the cover of the bumper can absorbthe most impact energy. So other parts of the car will not be destroyed. The bumper can transfer the kinetic energy into elastic energy in the test. Therefore, the width of thebumper should be enlarged in the vertical and horizontal. The crash-box is the maincomponent to absorb the impact energy in RCAR test. The structure of the crash-boxshould be optimized to improve the crashworthiness of the low-speed impact. So themain components of the car can be protected and the repairing cost can be reduced. Bycomparing the results from study on the regulations, there is relative low requirementof the car bumper performance in the pendulum test. In the RCAR and IIHS tests it wasindicated that a relative high performance is required. RCAR and IIHS regulations aresimilar with the reality. At present Chinese insurance association has not developed thelow-speed regulation for bumper system performance. So a low-speed regulationshould be developped according to vehicles and road conditions referring to RCAR andthe IIHS tests. The optimization models can be used to save time and costs in design ofnew car front bumper parts.