اثر اضافه بار بر ویژگی های چقرمگی

A controlled overloading of some structures containing sharp defects can lead to improvement of the integrity of the structures due to blunting the defect tip, enlarging the plastic zone and giving rise to residual compressive stresses at the defect tip. On the other hand, the overloading of a structure, free of sharp defects, to the plastic region can reduce the integrity of the structure. This is proved by impact and fracture toughness tests of specimens manufactured from sheets which were prestrained to the plastic region. While impact toughness was improved the fracture toughness was found to be reduced.