Research On Mass-spring Model And Simplified FEM Model For Side Impact

Side impact is a classic form of vehicle crash,500,000 people were killed and 1,000,000 people were wounded in vehicle traffic accident all over the world every year, a great number of which were caused by the vehicle side impact. There is no special statistic about accident caused by automotive side impact in China, but the fact---that the vehicle side impact is even more serious in China than in other primary countries in the world---is indicated by the large number of traffic accidents and low vehicle safety. Therefore, it is significant to research into the mechanism of side impact and to improve the design capability of side impact crashworthiness.Firstly, the side impact were introduced systematically, from C-NCAP side impact test (including test strategy and characteristics of Moving Deformable Barrier, MDB) and analyzing the process of side impact to the movement of dummy in the crash, injury mechanism and criteria. Then the modeling procedure for side impact FEM model is summarized, and a side impact FEM model was established and calculated. Comparing simulation results to the results of the C-NCAP side impact test, the model shows high consistence to the crash test, indicating high reliability of the model.In order to reveal more deeply both the mechanics and kinetic mechanism of side impact, a couple of guiding lines for the side impact crashworthiness design are brought out and a side impact mass-spring model established. Analytic solution of the model relating to the movement of both the test vehicle and MDB are proved that it can reflect the test process precisely, especially during the first 60ms, which is the most determinant. According to the results of the mass-spring model, a series of principles for enhancing crashworthiness and improving occupant protection are brought forward.In this dissertation, the sensitivity of the MDB and the movement of the test vehicle to the structure of side wall are further studied, and the results show that the former is not very sensitive to the latter in a certain range. The conclusion is proved in both the FEM model and the mass-spring model.According to the conclusion on sensitivity, a simplified FEM model derived from the full-scale FEM model is offered. The calculation efficiency of the simplified FEM is enhanced to be 7 times higher than the full-scale FEM model, benefiting from the reduced number of calculation. It is found that the simplified model can guarantee the preciseness of calculation at the same time of improving the efficiency, by comparing the body deformation,B-pillar displacement and the energy absorbed by the honey foam between full-scale model and the simplified model.Finally, the simplified model, with association to Design of Experiment, is applied to weight lightening and improvement of the side impact crashworthiness of the MPV, and it is demonstrated that the dominant calculation efficiency of the simplified model help to achieve the design goals with controlled cost.