COMPUTER DEMONSTRATION OF CRACK-GROWTH

Crack growth is simulated by means of a simple demonstration program. The fracture mechanism is assumed to consist of hole formation, growth and coalescence. This sequence is visualized on a PC-screen. Holes are assumed to be opened at particles. Several far-reaching simplifications are made, but the following features are taken into account: 1. Holes are opened when the ambient stress reaches a critical value, dependent on the size of the particle. 2. Hole growth occurs under a simple viscosity rule. 3. Hole coalescence takes place when the distance between two holes (or one hole and the main crack) becomes smaller than a certain critical distance. 4. Hole opening and growth causes decreasing stress in the neighbourhood. Several parameters can be varied: 1. Particle average size, size distribution and spacing. 2. Stress intensity factor (SIF). 3. Relation between stress required for hole opening and hole growth. 4. Smoothness of the macroscopic near-tip stress field. The results turn out to be about the expected ones. For SIF below a certain level (only approximately determinable because of randomized particle distribution) sustained crack growth does not occur. For SIF slightly above this level crack growth occurs at a low velocity and involves only one succession of holes. At a substantially higher SIF the velocity as well as the energy dissipation in the process region becomes higher since many more holes are involved. © 1990 Kluwer Academic Publishers.