Axial crashing analysis for tailor rolled square tubes with axially graded both wall thickness and material strength: Fid-Bau Portal

Axial crashing analysis for tailor rolled square tubes with axially graded both wall thickness and material strength

Lu, Rihuan / Liu, Xianghua / Chen, Shoudong / Hu, Xianlei / Liu, Lizhong

AbstractTailor rolled square tubes with continuous thickness variation along axial direction are successfully obtained by subsequent forming of tailor rolled blanks manufactured by variable gauge rolling technology. The crashworthiness of tailor rolled tubes and traditional equal thickness tubes under axial crashing tests are compared and analyzed. From the test results it can be known that the initial peak load of given tailor rolled tubes are ranged from 45kN to 58kN, which are 52–63% lower than that of traditional tubes. For the combined action of axial variable thickness and variable strength, the energy absorption value and energy absorbed efficiency of tailor rolled tubes respectively 11% and 10.7% larger than traditional tubes. The primary cause of increasing energy absorption is that more metal of tailor rolled tube be entered into plastic deformation stage. In addition, the folding of tailor rolled tubes is always stated to occur at the thin zone near the tube end. Then, it is gradually progressed to the thick zone with graded increased wavelengths. It is should be pointed out that the fold number of tailor rolled tubes after crashing is more than corresponding traditional tubes. According to the crashworthiness criteria, this novel tube structures produced by rolling technology are more suitable for energy absorbing structure. The finite element models are also established considering variation both in thickness and in material strength, and it was verified by experiments. Afterwards, these validated models are carried out to study the crashworthiness of tailor rolled tubes under different geometric parameters. It is concluded that the shorter tailor rolled tubes and proper length of thickness transition zone is of more benefit to improve energy absorption efficiency. It can be concluded that the optimization thickness distribution and material strength of tailor rolled tubes can be designed according to the actual multi-requirements, and can be large-lot manufactured by variable gauge rolling technology to maximize the energy absorption and material saving.

Graphical abstract

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Highlights•Tailor rolled tubes with axially varied thickness distribution are obtained.•Crashworthiness of tailor rolled tubes and traditional equal thickness tubes are compared.•Finite element models both considering thickness and material properties variation are established.•The load characteristic of tailor rolled tubes is more close to the ideal condition of energy-absorbing part.