城市轨道交通车辆切削式吸能管轴向冲击性能研究

Research on Axial Impact Performance of Cutting-Type Energy-Absorbing Tubes for Urban Rail Transit Vehicles

  • 摘要:
    目的 材料断裂失效参数是影响切削式吸能管轴向冲击性能的关键因素,直接决定着轴向冲击力的稳定性和切屑卷曲分离模式。因此,有必要从材料断裂失效参数出发,对切削式吸能管轴向冲击性能进行研究。
    方法 对3种典型缺口试样进行拉伸断裂试验,获得材料在不同应力状态下的断裂应变。进而,采用有限元方法模拟3种试样的拉伸断裂试验,获得试样的平均应力三轴度,拟合得到基于Johnson-Cook模型的材料断裂失效模型。对吸能管进行轴向冲击有限元仿真,通过将仿真值与冲击试验结果进行对比,验证了模型的准确性。在此基础上,进一步研究了切深和切宽对吸能管轴向冲击性能的影响。
    结果及结论 拟合得到的Johnson-Cook材料断裂失效模型可有效模拟切削式吸能管切屑卷曲模式,并得到稳定准确的切削力。切削力的峰值力和平均力与切深呈正相关,切深每增加0.4 mm,平均力增大约76.3 kN;随着切宽增加,峰值力和平均力均增大,但增大幅度不断减小。

     

    Abstract:
    Objective As key factors affecting the axial impact performance (AIP) of cutting-type energy-absorbing tubes (CEAT), material fracture failure parameters directly determine the stability of axial impact force and the curling-separation mode of chips. Therefore, it is necessary to investigate the AIP of CEAT from the perspective of material fracture failure parameters.
    Method Tensile fracture tests are carried out on three typical notched specimens to obtain the fracture strain of the material under different stress states. Furthermore, the tensile fracture tests of the three specimens are simulated using finite element method, and the average stress triaxiality of the specimens is obtained. A material fracture failure model based on the Johnson-Cook model is fitted accordingly. Finite element simulations of axial impact on CEAT are conducted, and the accuracy of the model is verified by comparing simulation results with impact test data. On this basis, the effects of cutting depth and cutting width on the AIP of CEAT are further studied.
    Result & Conclusion  The fitted Johnson-Cook material fracture failure model can effectively simulate the cutting-curl mode of CEAT, yielding stable and accurate cutting force. The peak cutting force and average cutting force are positively correlated with cutting depth; the average force increases by approximately 76.3 kN for every 0.4 mm increase in cutting depth. With the increase of cutting width, both the peak force and average force will rise, while the growth rate gradually decreases.

     

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