Study On Energy Absorption Capability Of Thin-walled Invertion Tube And Its Application In Crash Box

With the increasing rate of accidents, the crashworthiness of energy-absorbing structure is playing a more and more important role in the process of protecting life and property. Inversion tube as a new energy-absorbing structure is found possessing of excellent load stability and energy absorption performance, but the current research on application is very lacking in the domestic. As to the need of crash safety, the research work on the deformation modes and energy absorption property of inversion tube are carried out in this article, as well as some structure design works of inversion energy absorbing structure, and are going to be applied to the automobile crash box. The main works of the dissertation are as follows:(1)Discussed the deformation modes and energy absorption mechanism of free inversion. A comparative study is conducted to compare the energy absorption characteristics of circular tubes, hexagonal tubes, multi-cell tubes and inversion tubes. The results show that the load consistency of inversion tubes is the best, while the effective compression distance is shorter than others. In addition, the research on the deformation modes of inversion tubes shows that the ring width and loading velocity both have effect on the deformation tendency, and the tube material has effect on the deformation stability.(2)Introduce some design projects of two-section inversion tubes with controllable deformation by using chamfer and variable thickness, making the effective compression distance maximum. Introduce the size design equations of two-section and three-section tapered inversion tubes, and the equations will make the effective compression distance maximum and have been verified by numerical simulation. Then designed the three-section inversion tubes by using chamfer and variable thickness. Present two kinds of molding processing scheme according to current tube inversion technology.(3)The energy absorption way with inversion deformation is applied into the structure design of automobile crash box, using the interior space of front rail to improve the compression distance. At the same time, better the capability of absorbing energy by improving the deformation stability under oblique impact by filling with aluminum foam.(4)Executing axial shocking simulation test on filled crash box. For the inversion tube of the same thickness, both of the energy absorption and peak crushing force will decrease linearly for the reason of the aluminum foam porosity increasing. Specific energy absorption will also decrease according to the porosity increasing. However, the outstanding feature is that the smaller the wall thickness is, the larger the drop margin is. At the same time, it is found that the crush force efficiency of the aluminum foam filling structure is highest of which the porosity is about 82.4%.(5)The multi-objective structure optimization with the optimization objectives that the maximum energy absorption in a certain compression distance and minimum weight is proposed.Response surface surrogate model are established, and the Pareto optimal solution set is obtained through Non-dominated Sorting Genetic Algorithm, applying reference for structure design.