ANALYSIS OF DYNAMIC CONTACT OF CRACKS IN VISCOELASTIC MEDIA

A novel single-step method is proposed for the analysis of dynamic res ponse of contactable crack in viscoelastic media. In the method, a two -level algorithm is employed for dealing with a non-linear boundary co ndition caused by the dynamic contact of crack surfaces. At the first level, an explicit method is adopted to calculate nodal displacements of the global viscoelastic system without considering the effect of dy namic contact of cracks and at the second level, by introducing the co ntact condition of crack surfaces, a group of equations of smaller ord er is derived to calculate dynamic contact forces on the crack surface s. The method is very convenient and efficient for the analysis of pro blems of dynamic contact. The accuracy and the stability condition of the method are also discussed in the paper. It is shown that the accur acy of the method is of the second order and the numerical stability c ondition is wider than that of other explicit methods, such as the pre dictor-corrector method and the explicit difference methods in which a backward difference form is used for the velocity term of the equatio n. Numerical results are obtained for the impact of a thick plate with an infinite crack. The results demonstrate that when damping exists, the high-frequency oscillation in the solution of contact force is red uced and the opening of crack faces becomes smaller.