THE ROLE OF RESIDUAL STRESS STATE IN THE SUB SURFACE IN FRONT OF THE CRACK TIP AFTER TENSILE OVERLOAD TO CRACK PROPAGATION BEHAVIOR

摘要

To confirm whether residual stress state on the surface in front of the crack tip controls the crack propagation after overloading or not, in the present study the investigation was conducted by observing the behavior of crack propagation after overloading under constant amplitude load with positive and negative stress ratio, respectively. After machining away the surface of the flat section of specimens in several millimeter in depth to remove residual stress developing by a single tensile overload in front of the crack tip, the crack propagation still behaved as the same as the unmachined one. It is an indication that the presence of residual stress in the subsurface dominates the crack propagation behavior on the following overload.