A CONTACT FORCE MODEL FOR THE DYNAMIC-RESPONSE OF CRACKS

A finite element method is proposed for the time-domain analysis of th e dynamic response of cracks. The stress equilibrium and displacement continuity conditions at the point of dynamic contact are ensured in t his method. By using this method, the contact normal stress and its di stribution as well as the state of motion on the surfaces of the crack can be determined. The model satisfactorily simulates the process of contact, slip and separation of the two crack surfaces and can be used to study the problems of elastic wave scattering due to cracks and cr ack extension due to impact or cyclic loading. Numerical examples are used to demonstrate the effectiveness and accuracy of the established model and the results are compared with those obtained by ignoring the contact problem. It is found that the effects of dynamic contact on t he motion of the crack surfaces and on that of the near-field are sign ificant.