Study on fault vibration characteristics of shield cutters based on FEM-MBD

The geological conditions in coal mine tunnel construction are complex, the vibration impact of shield machine due to rock breaking easily leads to cutters failure, thus causing safety problems and causing economic losses. In order to explore the fault vibration characteristics of shield cutters in rock breaking process, numerical simulation of rock breaking of single-blade fault cutters is carried out based on finite element-multi-body dynamics coupling model. The accuracy and reliability of simulation results are verified by comprehensive application of dynamic energy conservation law and hourglass energy control theory, and the fault vibration characteristics of cutter center, cutter body outer side and rock surface outer side are analyzed, and the influence of penetration degree and blade type on fault vibration characteristics is explored. The result showed that: in the three stages of initial contact-leaving rock-secondary contact, the axial and lateral linear velocity of cutter body decreases sharply, the normal linear velocity increases sharply, and the axial and lateral angular velocity of cutter increases sharply at the initial stage of contact. During the second contact period, the axial and lateral linear velocity of the cutter body increases sharply, the normal linear velocity decreases sharply, and the axial and lateral angular velocity of the cutter decreases sharply, and an obvious deviation trend is formed. And that, the fault characteristics of eccentric grinding cutter will appear earlier than fracture cutter, but it takes longer to fully manifest, and the vibration intensity of cutter decreases significantly with the increase of wear degree. In addition, angular velocity and angular acceleration data on rock surface are derived by displacement gradient tensor and numerical differentiation method, and it is found that fault vibration characteristics are not obvious on the outer side of rock surface. Meanwhile, through conducting indoor shield fault roller cutter rock-breaking experiments, the accuracy and rationality of the numerical simulation were verified. This paper provides a theoretical basis for the identification of fault cutter in multi-cutter system and complex shield construction conditions.