脆性颗粒材料的应变率效应机理研究

INVESTIGATIONS ON THE INTRINSIC MECHANISMS OF STRAIN RATE EFFECTS OF BRITTLE GRANULAR MATERIALS

利用分离式Hopkinson压杆(SHPB),对干燥石英砂进行了被动围压下的动态压缩实验,发现石英砂表现出了明显应变率效应.通过激光粒度分析测量了动静态压缩后的试件的级配曲线,发现同一应力水平下准静态压缩后比动态压缩后的试件的颗粒破碎量更大.而通过拟合相对破碎率与外力功之间的关系,发现准静态压缩在颗粒破碎方面能量利用率更高也即破碎效率更高,而这正是脆性颗粒材料应变率效应的本质原因.

With the modified Split Hopkinson Pressure Bar（SHPB） ,the dynamic and quasi-static com pression responses of silica sand were tested,exhibiting obvious stress-strain effects. With laser diffractom- etry,corresponding grain size distributions of the specimens after dynamic and quasi static loading were measured. Under the same stress level, the breakage amount in the specimen after quasi-static compression was bigger than that after dynamic compression. Fitting the relationship of the relative breakage to external work,the results show that the breakage efficiency of quasi static loading was much higher,which is the intrinsic mechanism of strain rate effects for brittle granular materials.