针对SHPB试验中试件的轴向应力均匀性问题,采用一维弹性波理论.推导了具有任意形状前沿的入射波加载下,试件内应力的时空分布计算公式。以脉冲前沿的上升时间为参数.将矩形、梯形和坡形3种典型的输入脉冲统一表示为梯形波的形式,计算了不同入射波上升时间和不同试件-压杆波阻抗比情况下试件中的应力传播过程,得到了相应的应力均匀度时程曲线以及应力平衡时间。分析了入射波上升时间和试件-压杆波阻抗比对应力平衡时间的影响,得到了一些有意义的认识,为SHPB试验的设计与分析提供了一定的理论依据。
Stress uniformity along the axial direction in specimens of split Hopkinson pressure bar (SHPB) tests was investigated. By theory of one-dimensional elastic stress wave, the temporal and spatial distribution of stress in specimen induced by incident pulses with any rising shape was derived. Wave propagation processes in specimens were calculated under rectangular, trapezoidal and sloping waves, which were uniquely expressed as the trapezoidal type by the parameter of rise time. Stress uniformity histories were obtained, and the influences of relative rise time of incident pulse and specimen-bar relative mechanical impedance on relative time required for stress uniformity were investigated. Researched results can provide guidelines to design and analyze SHPB tests.