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为通过冲击点位移获得复合材料层压板的低速冲击性能,首先,在层压板落重冲击试验中,使用高速激光位移传感器测得冲击点背部的位移和速度;然后,基于弹簧-质量冲击模型,以冲击点位移计算了冲击接触力,并通过无损冲击试验标定了弹簧-质量模型参数;接着,模拟了有损伤冲击过程的接触力,利用实测冲击点速度响应判定了分层产生的时刻,并根据模拟结果得出了分层阈值力;最后,根据无损检测结果进行了层压板抗弯刚度的折减,使用弹簧-质量模型计算了产生冲击损伤后的接触力及能量吸收曲线,使用冲头和冲击点背部位移计算凹坑的实时深度。结果显示:结构受冲击发生分层时,由于层压板刚度的突降,冲击点速度出现剧烈震荡,该现象可以作为结构出现分层损伤的识别特征;产生冲击损伤后的接触力及能量吸收曲线的计算结果与试验测试结果吻合。计算所得凹坑的实时深度随冲击能量的变化趋势与冲击后测试的凹坑深度变化趋势一致。这些结果表明提出的基于非接触测量技术的方法可用于无法直接测量接触力情况下的层压板冲击性能分析。
In order to obtain the low-speed impact performance of the composite laminates through the impact point displacement, firstly, the displacement and velocity of the back of the impact point were measured by using the high-speed laser displacement sensor in the falling impact test of the laminate. Then, based on the spring-mass impact model, The impact contact force was calculated from the impact point displacement, and the spring-mass model parameters were calibrated by the non-destructive impact test. Then, the contact force with the impact damage process was simulated and the delamination time was determined by the measured impact velocity response. According to the simulation results, the delamination threshold force is obtained. Finally, the bending stiffness of the laminate is reduced according to the results of non-destructive testing. The contact force and energy absorption curve after impact damage are calculated by spring-mass model. And the back of the impact point displacement of the real-time calculation of pit depth. The results show that when the structure is stratified by impact, the velocity of the impact point appears violently turbulent due to the sudden decrease of the stiffness of the laminate, which can be used as the identification feature of the stratified damage. The contact force and the energy absorption curve after the impact damage The calculated results agree well with the test results. The trend of the real-time depth of the pit calculated with the impact energy is consistent with the trend of the pit depth after the impact test. These results show that the proposed method based on non-contact measurement can be used to analyze the impact properties of laminates when the contact force can not be directly measured.