| Safety, energy saving and environmental protection have always been three topics in the process of automobile design and manufacture. The dissimilar metal body cause the extensive concern of automobile enterprises. Dissimilar metal front rail become one of research hotspots in this filed because its effect on crash energy absorption and the lightweight. Therefore, the study of crashworthiness of top-hat dissimilar metal thin-walled tube has great significance because it is regarded as the best simplified structure of automobile front rail.Firstly, an axial quasi-static compression test of dissimilar metal top-hat thin-walled tube was carried out in this thesis, and according to the test results, a finite element modeling method is validated. Then there is a comparison of crashworthiness between dissimilar metal and single metal top-hat thin-walled tubes under axial impact load based on this finite element model. The results show that aluminum-steel hybrid top-hat tube has better energy-absorbing performance and higher level of lightweight than pure steel top-hat tube. In addition, the geometric parameter analysis of top-hat board thickness and panel thickness was made to check their influence on crush performance of top-hat tubes which have different material combinations. and found that the increase of top-hat board thickness had a significant improvement of energy absorption and energy absorption efficiency. However, the increase of panel thickness makes a small promotion on energy absorption of top-hat tube. Besides, in most combinations of the thickness, the dissimilar metal top-hat tube has better crush performance than single metal top-hat tube.Secondly, in order to meet the requirements of following oblique crushing test of top-hat tube, a new type of oblique crushing test fixture was designed and manufactured. Compared to the previous test fixture, its advantages are that it can be applied to thin-walled tubes which have a variety of cross section shapes and sectional dimensions, and it also creates continuous variation of the impact angle.Finally, the oblique crush performances of dissimilar metal and single metal top-hat tubes under different impact angles were investigated based on the finite element model which was validated again by oblique quasi-static compression test. The results show that aluminum-steel hybrid top-hat tube is superior to single steel top-hat tube on overall crush performance. It's worth noting that dissimilar metal top-hat tubes have obvious advantages respectively on the deformation mode and the energy absorption characteristic. In conclusion, dissimilar metal has a wide application prospect in the design and manufacture of automobile front rail. |
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