VISUAL SIMULATION OF FATIGUE-CRACK GROWTH

An attempt has been made to visually simulate fatigue crack propagatio n from a precrack. An integrated program was developed for this purpos e. The crack-tip shape was determined at four load positions in the fi rst load cycle. The final shape was a blunt front with an ''ear'' prof ile at the precrack tip. A more general model, schematically illustrat ing the mechanism of fatigue crack growth and striation formation in a ductile material, was proposed based on this simulation. According to the present model, fatigue crack growth is an intermittent process; c yclic plastic shear strain is the driving force applied to both state I and II crack growth. No fracture mode transition occurs between the two stages in the present study. The crack growth direction alternates , moving up and down successively, producing fatigue striations. A bri ef examination has been made of the crack growth path in a ductile two -phase material.