玻璃-橡胶混合颗粒的力学响应研究

通过直剪实验和离散元模拟, 研究掺杂了橡胶软球的玻璃体系的力学响应. 改变颗粒固体中橡胶颗粒的含量, 研究体系剪切强度以及剪胀变化等特性, 发现随着橡胶颗粒的增加, 会出现剪胀到剪缩的相转变现象, 且混合颗粒固体的弹性有了很大的提高. 实验研究发现, 随着体系中橡胶颗粒含量的增加, 剪切屈服强度值逐渐减小, 体积发生从剪胀到剪缩的相转变现象, 但临界剪切强度在一定橡胶颗粒含量范围内保持一致; 实验所采取的剪切速率下, 应力应变曲线能较好重合, 即实验处于率无关区域; 混合样品的屈服强度值随正压力的增大而增大. 离散元模拟也得到了上述结果, 另外模拟还发现, 随着橡胶颗粒含量的增加, 颗粒的平均配位数增大; 橡胶颗粒含量和正压力对剪胀-剪缩相转变的位置有影响, 橡胶颗粒含量较小时, 在较大的正压力下易发生相转变现象, 且剪胀-剪缩相转变点对应的平均配位数在5.6-5.9之间; 在橡胶颗粒含量小于30%时, 混合颗粒样品的残剪强度与不掺杂的颗粒体系相近; 大于30%时, 残剪强度随橡胶颗粒含量的增加而减小; 残剪强度随正压力加大而增加.

Mechanical response study of glass-rubber particle mixtures

Mechanical response of mixtures composed of glass and rubber particles are investigated in direct shear experiments in laboratory and by means of discrete element method simulations. The mixtures are prepared with different contents of rubber fractions. It is found that, with increasing rubber particles, volume phase transition occurs from dilatancy to reduction, and the elastic properties of the mixtures are improved. Experimental results show that, as the rubber particles (up to 30% in volume) are added, the value of the shear stress falls, and the volume phase transition occurs, but the critical states are the same. The shear stress is independent of shear rates, however, it grows with the normal force. We have obtained the consistent results in the simulation. Furthermore, statistical analysis of the simulation results shows that the average coordination number is raised with the increase of rubber particles. Volume phase transition occurs at low rubber fraction when the normal force is large. It is very important to keep in mind that the average coordination number is always between 5.6 and 5.9 at the phase transition points even under different normal forces. When the rubber fraction is less than 30%, the residual shear strength is nearly the same as in the system of glass beads. However, the residual shear strength decreases when the rubber particles increase to the fraction larger than 30%. Meanwhile, the residual shear strength increases with the normal pressure.