Abstract
Fracture toughness K_<IC> or J_<IC> is generally used as criterion for safety design. These criteria are defined under plane sirain condition. Shear lips on crack surface is caused in case of thin plates fracture. Therefore, fracture mechanism in thin plates is not clarified. And some of these fracture behavior depends on loading speed. In this study, three point bending fracture experiments are demonstrated to gain basic data for elastic plastic fracture in thin plates. The specimens are consists of aluminum alloy. Pure mode I and mixed mode fracture experiments are done under quasi-static loading and dynamic loading. Roughness on crack surfaces are evaluated using laser focus displacement meter. Fracture path, crack surface trend and surface roughness are depended on loading speed.
