一种新的内翻管理论模型及其耐撞性研究

A NOVEL THEORETICAL MODEL AND CRASHWORTHINESS RESEARCH FOR INTERNAL INVERSION TUBE

圆管圆角模具内翻作为金属薄壁管的一种变形模式有着良好的吸能特性.现有关于内翻模式的理论模型均假设变形区曲率恒定且很少有关于翻转全过程翻转力的研究.通过试验测试和有限元模拟对6063铝管的内翻过程进行了研究,并结合外翻模式变形特点详细探讨了内翻模式的变形特点.根据试验和有限元结果提出了一种新的描述内翻模式的理论模型,该理论模型在同时考虑了变形区曲率变化和管壁增厚的基础上,对内翻全过程的翻转力也进行了预测,进而可以得到内翻模式总吸能和比吸能的理论结果.通过与前人理论结果和试验结果的对比得到,文章理论结果更吻合试验和有限元结果.最后,根据验证后的理论模型对内翻模式的耐撞性进行了分析讨论,结果表明:存在最优模具半径使得内翻稳态力、总吸能和比吸能最小;增大圆管壁厚可显著提高内翻模式吸能特性;增大圆管半径能提高内翻稳态力和总吸能,但会降低比吸能.新的内翻理论模型为描述内翻变形模式和内翻管作为吸能元件提供了理论依据.

As a deformation mode of thin-walled metal tube,the internal inversion mode of circular tube over a circular die has good energy absorption characteristics.However,in all previous theoretical models,the curvature in the deformation area is assumed to be a constant value and few of them pay attention to the inversion force of the whole inversion process.The internal inversion process of 6063 aluminum tube is studied by experimental testing and finite element simulation,and the deformation characteristics of the internal inversion mode were discussed in detail.Based on the experimental and numerical results,the curvature is found to be varying in the deformation zone and the wall thickness has thickened.Then a novel theoretical model for the internal inversion mode is proposed based on the characteristics of the deformation mode for internal inversion process.Additionally,the novel theoretical model can predict the internal inversion force throughout the whole internal inversion process,enabling us to obtain theoretical results for both total energy absorption(EA)and specific energy absorption(SEA).Furthermore,upon comparison with the previous theoretical results,the current theoretical results exhibit a higher degree of both experimental and numerical results.Finally,the effects of tube wall thickness,tube average radius and die radius on crashworthiness indicators are theoretically investigated using the validated theoretical model.The results show that there exists an optimal die radius which minimizes the internal steady inversion force,the total energy absorption and the specific energy absorption.Increasing the wall thickness can significantly enhance all crashworthiness indicators.Augmenting the tube average radius can increase both the internal steady inversion force and the total energy absorption,while decrease the specific energy absorption.The novel inversion theoretical model provides a theoretical foundation for characterizing the internal inversion deformation mode and utilizing the internal inversion tube as an energy absorber.