ON A DYNAMICALLY ACCELERATING DUGDALE-ZONE IN ELASTIC AND VISCOELASTIC MATERIAL

A closed form solution and numerical simulation are presented for a dy namically accelerating, semi-infinite, anti-plane shear crack with a D ugdale-zone in an Achenbach-Chao linear viscoelastic solid in the limi ting case of a vanishing equilibrium shear modulus. The solution is va lid for arbitrary forward crack motion at speeds below the glassy shea r wave speed. Motivated by previous experimental observations, special attention in the numerical simulation is given to the case of constan t speed for the material crack-tip, which is defined to be the trailin g edge of the Dugdale-zone. Even for this special case, the motion of the mathematical crack-tip, defined to be the leading edge of the Dugd ale-zone at which the stress intensity factor cancellation condition i s applied, is non-steady, necessitating the full generality of previou sly developed dynamically accelerating crack solutions. Comparison wit h results for elastic material is made and implications are drawn on t he use of a critical crack opening displacement fracture criterion. Co pyright (C) 1996 Elsevier Science Ltd