Parameterized Model For Conceptual Design Of Sedan Side Crashworthiness

1. PrefaceNow more and more people in China know that it is really important to buy a safer car, because there are more cars here, and with it the spreading technologies and common sense of safety. While the traffic accidents caused by side impact crashes still have made many people injured even killed. And the road crosses in China are mainly planar, which help to make thing even worst. The side body of car is rather thin, which can provide little capability to prevent itself from deformation or to absorb the impact energy. That is to say, the occupant is subject to be injured and could hardly be protected in a side impact. So we have to make sure the side crashworthiness of vehicle, which is the basis of occupant protection system.The CAE technologies have been applied to car structure design in many fields, and the vehicle safety design flow has been transferred from traditional serial flow pattern to parallel flow pattern, which is also called CE (concurrent engineering). And the CE could make the vehicle safety analysis done during the early period of design, conceptual design phase. So that there could be an effective direction for the next step design to avoid faults which could not be corrected. The conceptual design phase is the most important one of the whole design flow, because it is the base of the design and the key direction of the design. Modern computers and CAE technologies have developed quickly and made many design analyzed in the phase of conceptual design. It is the power of vehicle design development.In the phase of conceptual design, an approximate simulation could be made by CAE technology. It could help to design, compare and analyze the vehicle structure. This method could be used with clear concept, close result, quick computation and in-control error. So that a quick optimal structure scheme could be found to be the input of next step analysis, which is also the base of detail design phase.2. Content The side crashworthiness has been studied using large deformation non-linear FEM theory and explicit nonlinear finite element software ESI/PAM-CRASH which is developed by a French company. The main content of this study is as follows.In this paper, situation of the research of passive safety and the domestic vehicle usage have been learned to introduce the signification of car side impact crashworthiness research, and with it the occupants injury mechanism and the vehicle side structure characteristics. With the development of safety regulations and market needs, the safety research methods have become a lot. Under a mature research condition, CAE analysis in conceptual design phase is most important for the vehicle side crashworthiness.This paper introduces the application of CAE technology in vehicle design and compares FMVSS 214 with ECE R95. According to ECE R95, this paper introduces the detailed FE ( finite element) model for the side impact simulation, which has been validated.In addition, this paper has analyzed the characteristic of vehicle structure deformation in the side impact. The entire deformation and local change both have been studied. So the simplified element types could be decided. Then the nodes position and elements'properties could be abstracted from the detailed model. Finally, the parameterized model has been set up from the simplified elements with inertia and stiffness parameters.Learn the importance of side crashworthiness study. Study the present situation and trends so as to decide the useful theory and methods. To design the side crashworthiness during the conceptual design phase, the basic principle to setup the parameterized model has to be made. Learn the validated full FE model and study its simulation results, so that to get a scope view of the side deformation of the vehicle in side impact. This can lead to the nature so that we could find the main loading structure, the feature of deformation and the loading path. Decide the main deformed place as the rigid point position according to the side deformation characteristics. And abstract the main structure to simplified elements accordingly. Find the sub-structure deformation ways, so that the simplified elements could have inertia properties and stiffness properties. Setup the parameterized model of side impact and decide the parameters. Run the simulation test of side impact and do the validation. Make sure the model is useful while during the conceptual design phase.In the end, the CAE Driven flow of concept design for crashworthiness has been introduced. This paper introduces an index for side crashworthiness and an easy way for concept design with the parameterized model. So a parameter study has been done to find the most sensitive parameters. Using a respond surface analysis, this paper does a design of crashworthiness and finds a optimal stiffness parameter scheme.3. SignificanceA parameterized model takes less computation resources at a rather quicker speed with reasonable accuracy. All these make it fit for the conceptual design. With its characteristic, we could find the main loading path and assess the contribution the main energy-absorbing structure in a short time. So that a quickly parameter study work could be done. And multi cases could be compared and optimized.The parameterized model can lead to less overall-concept design faults so as to limit the modification of designed concept. And it applied CAE-Driven design method, which is the trend of modern design, to the side crashworthiness design flow.It could shorten the design cycle, cut the cost and make the design more effective. It is the key point that the parameterized model could design the side crashworthiness during early design phase so that the design quality could be ensured.