轴向静载对变截面杆中应力波幅值的影响

Effects of axial static loads on stress wave amplitude in at apered aluminum rod

针对变截面构件受到动静组合荷载作用的工程实际,研究轴向静载对变截面杆中应力波幅值的影响。选用铝制备锥形直杆试件,基于动静组合加载试验系统,对试件进行不同轴向静载工况下的应力波传播试验。通过沿轴向不同位置处布置的应变片测定应变时程曲线,以动应变幅值随传播距离及静载的变化规律表征其传播衰减特性。结果表明,轴向静载对应力波下降沿有较大的影响;随着静载的增大,直锥铝杆中应力波传播速度先小幅增加后趋于不变;幅值空间衰减系数呈现“小幅降低—基本不变”的变化特征;试件入射端响应幅值持续减小,且其变化率先逐渐增大,后趋于不变;不同测点的幅值均随静应力的增加近似线性减小,越远离入射端,幅值的变化率越小。

Aiming at engineering practice of variable cross-section members being subjected to coupled static-dynamic loads,effects of axial static stress on amplitude of stress wave in a rod with variable cross-section were studied.Based on a SHPB test system with coupled static-dynamic loading,stress wave propagation tests for a tapered aluminum rod were performed under different axial static loads.Time history curves of dynamic strain were measured with strain gauges arranged at different positions in axial direction,and propagation attenuation characteristics of stress wave were characterized with variation laws of dynamic strain amplitudes versus propagating distance and static loads.The results showed that axial static loads have a larger effect on decrease in stress wave;with increase in static loads,stress wave’s propagating velocity in the tapered aluminum rod slightly increases firstly,and then tends to be constant;amplitude spatial attenuation coefficient reveals a variation feature of“slightly decrease-almost constant”,while response amplitude at the tapered rod’s incident end decreases continuously,its rate gradually increases firstly and then tends to be constant;amplitudes of different strain gauges decrease almost linearly with increase in static loads,the farther the distance from the incident end,the smaller the decrease rate of amplitude.