动静载荷耦合作用下PDC刀具的失效机理

运用应力波理论分析了冲击-静压切削模式下PDC刀具的破损机理，得出了冲击应力波的幅值、入射角（刀具侵入角）、刀-岩接触间隙，以及在接触面上的多次透、反射造成加载-卸载-再加载的循环，对破岩效果和PDC刀具破坏有很大影响.在自行研制的动静态多功能岩石破碎试验台上，以砂浆块和花岗岩为试验对象进行了冲击-静压切削破岩试验.结果表明：在硬岩破碎中，PDC刀具的破坏模式主要是轴向崩裂、冲击压碎和径向崩裂3种；施加一定的静压可使刃面与岩面充分接触，有利于应力波的传播，从而提高破岩效果和PDC刀具的使用寿命.

Mechanism of PDC cutter failure under coupling dynamic and static loads

The failure mechanism of PDC cutters were analyzed with the pattern cutting under coupling dynamic and static loads by applying the stress wave theory. The amplitude and incidence angle of stress wave，clearance of interface between impacted rock and PDC cutter and cyclic times of loading—unloading—loading resulted from stress wave’s transmission and reflection at the interfaces greatly affect the damage of the cutters and the effects of rock fragmentation. On the multifunctional testing device，the cutting test under coupling dynamic and static loads were conducted on mortar and granite block. Experimental results show that main damage patterns of PDC cutters are axial cracks， impact crushes and radial cracks. During the impact testing， the cutter and the rock surface could contacted adequately by loading certain static pressure. It was useful for stress wave propagation， improved the effects of rock fragmentation and service life of PDC cutter.