牙轮钻头在井底破碎岩石过程中受顶部钻压、自身动载荷以及井底接触岩石的随机冲击碰撞作用，存在牙齿与岩石交替压入、刮切和滚动的运动状态，受力情况相当复杂。论文基于岩石弹塑性本构关系和等效塑性应变的岩石破坏准则，考虑井底围压以及钻头与岩石互作用随机接触碰撞，采用有限单元法建立了牙轮钻头与井底岩石互作用下系统非线性动力学模型。探讨了牙轮钻头在破碎井底岩石过程中的运动规律及力学性能，并对岩石破碎坑的形成过程进行了阐述，为有效预测和控制井眼轨迹的形成，实态工况下整体钻柱系统耦合非线性动力学研究提供了理论依据。

In the process of rock-crushing on bottom of hole， drilling pressure、self dynamic loads、random impacts and contacts of cone bit and rock on the roller cone bit system is considered. With alternate pressing-in， scraping and rolling， the motion state and stress of cone bit is extraordinary complex. Based on plastoelastic constitutive equations of rock and equivalent plastic strain damage principle also considering the confining pressure and random loads of bit and rock， nonlinear dynamic model of roller cone bit-bottom rock system is set up using the FEM method. Kinematics law and mechanical property of roller cone bit system are discussed. Also the formation process of craters on the rock is stated in this paper. The research results lay down a theoretical basis to forecast the formation of hole trajectory、establish foundation for nonlinear dynamic theory of drill string system coupling vibration in the actual work condition.