An approximate method for evaluating the fracture process zone near mode II dynamic crack tip

Abstract

Fracture process zone is the key for understanding the nonlinear fracture of quasi-brittle materials. Evaluation of the shape and size of fracture process zone near mode II dynamic crack tip is still a problem unsolved completely at present. The analytical methods for study on dynamic crack like integral transformation method and Wiener-hopf method are not easy to be used to calculate the stress fields near dynamic crack tip. So far the studies on fracture process zone near dynamic crack tip mostly focused on the experimental and numerical simulations. An approximate method for evaluating the shape and the size of fracture process zone is proposed and the feasibility of the new method is demonstrated by comparing with the results calculated based on the well-known stress fields. The shape and size of the fracture process zone near the mode II dynamic crack tip in dependence on crack propagation velocity are determined based on the approximate method. The results show that the areas of fracture process zone calculated based on the new method are nearly the same with the results calculated based on the well-known stress fields under plane stress condition and plane strain condition by the Von Mises criterion. The approximate method can provide a good reference for determination of the fracture process zone near mode II dynamic crack tip since no analytic method has been found for evaluating the fracture process zone near dynamic crack tip to the authors’ knowledge. The fracture process zone near mode II dynamic crack tip is distributed symmetrically with respect to crack plane and increases with the crack propagation velocity. The area of fracture process zone changes more rapidly when the Rayleigh wave velocity is approached. The areas of fracture process zone calculated under plane stress condition are bigger than these calculated under plane strain condition.