Simulation And Validation Of Crash Performance Of Composite Energy Absorption Cones And Research On Their Energy Absorption Mechanisms

With the rapid development of economic and automobile production technique, the carbecomes a popular means of transport for people today. At the same time, many attendantproblems cause the attention of car manufacturers and automotive consumers, which mainly inenvironmental issues caused by automobile exhaust emissions and the safety of cars.With the dramatic increase in the number of cars, traffic congestion became more and morenormal. As a result, car accidents also increased. In order to reduce the incidence of automobileaccidents, some measures had been made. on the one hand, the government continue to perfect thetraffic laws, on the other hand the car manufacturers adopt adequate security facilities in the car.The most commonly used in automotive safety facilities are airbags, ABS anti-lock brakingsystems, car bumper beams, car energy absorption boxes and so on. In addition to the problem oftraffic congestion, environmental problems caused by vehicle exhaust emissions also fix people’sattention a lot. Thus reducing vehicle exhaust emissions to improve energy efficiency is necessary.Faced with such circumstances, many researchers considered to use other materials which is lightand good mechanic property to replace the use of traditional metal material. The material can notonly reduce the body weight of the car and increase the fuel utilization but also improve the safetyperformance of vehicles. As a result, fiber-reinforced Composite went into the researchers’attention.Compared with conventional metallic materials, fiber-reinforced composite materials arelight weight and high mechanical performance. Fiber-reinforced composite materials in the automotive sector can not only improve the performance of the car crash, but also reduce theweight of the body which can improve fuel utilization to reduce emissions.This study comes from ESI-group, USCAR project. Intending to use carbon fiber reinforcedplastic energy absorption tubes to replace the traditional metal energy absorption boxes. Shape ofthe tube was designed as frustoconical, the smaller end of the crash cone is the front of energyabsorption tube, the size of crash cone was designed in accordance with the size of theconventional metal energy absorption box. Tube was molded by vacuum assisted molding method,carbon fiber prepreg was chosen as raw material to fabricate the half specimen with flanges,finally a complete pipe was made by assembling on the flanges. Such a production method can notonly increase productivity but also reduce production costs, which make it possible for theapplication of compression modeling during the industrial production.With the development of computer-aided analysis technology, finite element analysis hasbeen increasingly used to predict the performance in many fields. In this study, before themanufacture and the connection of the half carsh cans, their performance were simulatedrespectively. Five kinds of structures were designed named A1、A2、A3、A4、A5, Each kind ofstructure was simulated, the result showed that A3type had the best energy absorption propertyand it was stable during the crash test. According to the results of PAM-CRASH finite elementanalysis, A3structure was then carried out as the final structure to build the crash cones specimens.The finished pipes need to be assembled to fabricate the complete crash cans, the glue from DOWchemical company was selected to finish the connection of flanges. Before the drop tower tests theADHESIVE COS3D model was used to predict the crash performance, the result of the modelshowed that the glue was failure from the beginning of the test which resulted in the low energyabsorption. In order to validate this model, the specimen were tested, the results of the test is thesame situation with the prediction results. To solve the glue failure problem, the bolts assemblywas considered. Before the operation of bolts assembly, bolts assembly model also was simulated,the result showed bolts connection worked much better than glue only, the connected partsuccessfully hold the flanges during the drop tower test. the experimental results and the predictedresults are close, the crash cone absorbed11kJ when the crash length was about110mm,90%ofthe total energy. It is found that the carbon fibers of glue connected cone was not damaged enoughand the bolts connected cone were damaged enough, which resulted in its high energy absorption.