J and Limit Load Analysis of Semi-Elliptical Surface Cracks in Plates under Tension

Systematic detailed non-linear finite element (FE) analyses are described forsemi-elliptical surface cracks in plates under tension. Limit load solutions are obtainedfrom the FE J results through the reference stress method. The results show that theresponse of J to load depends on the ratio a/t, where a is the crack depth and t the thicknessof the plate. For a/t £ 0.5, J for any position along the crack front can be predicted by thereference stress method using a single limit load value, except for the points very close tothe plate surface. For a/t > 0.5, J can only be approximately estimated because no singlelimit load value can be found to satisfy all the FE J solutions along the crack front. Thelimit load data obtained from this work can be well predicted by a global limit loadequation developed by Goodall and Webster.