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    分离式霍普金森压杆试验中金属材料端面摩擦效应误差分析

    Error Analysis of Interface Friction Effect of Metal Material in Split Hopkinson Pressure Bar Test

    • 摘要: 采用分离式霍普金森压杆(SHPB)试验结合有限元模拟方法计算重构38CrMoAl高强度钢的应力-应变曲线,研究了端面摩擦因数(0,0.1,0.2,0.3,0.4,0.5)、子弹入射速度(20,30,40 m·s-1)、试样长径比(0.25,0.50,1.00)和试样形状(圆柱体,立方体)对端面摩擦效应引入的峰值应力、峰值应变测试误差的影响。结果表明:测试误差随端面摩擦因数的增大而增大,随长径比的增加而减小;截面面积相同的圆柱体和立方体试样的测试误差差值小于2%;端面摩擦因数较大时,控制子弹入射速度不能有效减小误差;将端面摩擦因数降到0.1以下,或是选用长径比1.00以上的试样,可以有效减小端面摩擦效应误差;试样中部和端面边缘处发生应力集中,随着试样长径比增大,应力集中部位占试样总长度比例减小,端面摩擦效应影响减小。

       

      Abstract: Stress-strain curves of 38CrMoAl high-strength steel were reconstructed by split Hopkinson pressure bar(SHPB)test and finite element simulation. The effects of end-face friction coefficient(0, 0.1, 0.2, 0.3, 0.4, 0.5), bullet incident velocity(20, 30, 40 m·s-1), sample length-diameter ratio(0.25, 0.50, 1.00)and sample shape(cylinder, cube)on the test error of peak stress and peak strain induced by end-face friction effect were studied. The results show that the test errors of peak stress and peak strain increased with the increase of end-face friction coefficient, and decreased with the increase of length-diameter ratio. With the same section area, the test error difference between cylindrical and cube samples was less than 2%. When the end-face friction coefficient was large, the test error could not be effectively reduced by controlling the bullet incident velocity. If the end-face friction coefficient of the sample was reduced below 0.1, or the length-diameter ratio of the sample was larger than 1.00, the end-face friction effect error could be effectively reduced. The stress concentration occurred in the middle and the edge of the end-face of the sample. With the increase of the length-diameter ratio of the sample, the proportion of the stress concentration in the total length of the sample decreased, and the influence of the end face friction effect decreased.

       

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