INITIATION OF CRACK-GROWTH IN LINEARLY VISCOELASTIC MATERIALS

The numerical scheme used in the determination of critical time for crack initiation in an infinite solid of linearly viscoelastic material subjected to remote monotonically increasing tensile stress is discussed. It is assumed that there exists a fracture process zone in front of the crack tip. The material property of the fracture process zone is regarded as linearly viscoelastic. The size of the fracture process zone is therefore time-dependent. A criterion of critical energy release rate for material fracture is used for the determination of critical time for crack initiation. Integral equations are formulated for the growth of the fracture process zone. Numerical solutions are found by means of Lee and Rogers' technique. In the computation, three-element solids are employed to represent the viscoelastic properties outside and within the fracture process zone. Examples are given to demonstrate the effects of the involved physical parameters. © 1990.