抄録
In this study, the evaluation method of fracture toughness values in the stable fracture process of Sheet Molding Compounds: SMC has been researched by the experimental fracture mechanical methods for an elastic-plastic material using a compact type test piece. The length of the stable crack growth is measured by the colored method by ink. Fracture toughness value is evaluated by J-value calculated by Rice's method. The stable fracture process is shown by R-curve. The value of Jin that is a fracture toughness value at the point of stable crack initiation is decided by the results.
Furthermore, the stable fracture process has been evaluated by the diameter of the damage zone at notch tip. The damage zone is obtained by the development of surface cracks. It is found that the diameter depends on the change of the fracture toughness values and the stable crack growth and also this relation is confirmed in the case of corrosion condition.
