复杂应力下两种胶结颗粒微观力学模型的试验研究

Experimental study on micro-mechanical model for two different bonded granules under complex stress conditions

将胶结颗粒理想化为两铝棒在指定位置处形成胶结,根据铝棒间胶结物厚度的不同,分别定义为有厚度胶结颗粒和无厚度胶结颗粒,对上述两种胶结颗粒进行一系列力学试验(包括:拉伸、压缩、压剪、压扭和复杂应力试验),从而对理想胶结颗粒的微观力学特性进行试验研究。试验结果表明:胶结厚度和法向压力对胶结颗粒的力学性能影响显著,随着胶结厚度的增大,试样的抗拉强度和延性均增大,其抗压特性由塑性硬化向塑性软化转变。无厚度试样抗剪和抗扭强度始终随法向压力的增大而增大,而有厚度试样则先随法向压力的增大而增大,当法向压力超过某一数值后,其强度又随着法向压力的增大而减小。在三维应力空间中(法向压力–扭矩–剪力)无厚度胶结颗粒的强度包线呈椭圆抛物面状,而有厚度胶结颗粒强度包线呈水滴状。

The micro-mechanical properties of idealized bonded granules are experimentally studied.The bonded granules are idealized by two aluminum rods glued together.Two types of bonded granules different from the bond thickness between rods are investigated,namely thin bonded rods and thick bonded rods.The mechanical tests are performed on these two bonded rods.The experimental results show that the bond thickness and the normal force have a significant effect on the mechanical properties of the bonded granules.The tensile strength and ductility both increase with the increase of the bond thickness.The compression curve exhibits strain hardening in the thin bonded rods but strain softening in the thick bonded rods.The peak shear/rotational strength increases with the increase of the normal force in the thin bonded rods,while they increase with the normal force at first,and then decrease in the thick bonded rods.Moreover,the strength envelope in the normal-torsion-shear space is an elliptic paraboloid in the thin bonded rods and a teardrop in the thick bonded rods.