混凝土材料的平板撞击实验与数值模拟研究

Study on Planar Impact and Numerical Simulation for Concrete Materials

通过实验和数值模拟研究了混凝土材料在强冲击载荷（平板撞击）下的动态特性.采用内径57mm的一级轻气炮实验结合高阻锰铜压阻计的动态测试技术,得到了C40混凝土试样的原始电压-时间波形曲线,并换算得到相应的应力-时间波形;分析应力波传播速度,得到材料的最大应变率约为55.40×10s-1,压力峰值区间为0.340~2.702GPa.实测结果表明：不同位置处的压力在快速上升至峰值后均随时间衰减,且冲击波峰值随传播距离快速衰减,呈现出明显的粘弹性特征和耗散特性.并利用LS-DYNA程序对混凝土试样的平板撞击实验过程进行了数值模拟,模拟的应力-时间曲线与实测压力波形走势完全一致,峰值很接近,整体吻合较好.

The dynamic characteristics of concrete materials under shock loading （planar impact） are studied with experiments and numerical simulation. By taking advantage of the inner diameter 57 mm of light gas gun, the planar impact experiments of C40 concrete samples are conducted. The samples’ voltage-time waveforms are recorded by means of high impedance manganin piezoresistive meter. And then the corresponding stress - time waveforms are derived. By analyzing the propagation velocity of stress wave, the maximum strain rate of the material is resulted with about 5 5.40 × 10s -1 , and the pressure peak is at about 0.340-2.702 GPa. The stress waveforms of different position found in the experiment indicate that the stress wave is on rapid rise to the peak then decays with time and the propagation distance. The results clearly show the rate dependent features of concrete on the viscoelastic characteristics and dissipation. LS-DYNA program is used to simulate the process of impact experiment and stress-time curves of concrete. Experiment stress waveforms are in good agreement with simulated ones.