Damage behavior within local materials at different stress states

In order to study the damage behavior within local materials at different stress state, two kinds of doble-hole tests were carried out.The thickness of the specimen is 1 mm.The radius of hole are same in the first specimen.However, the radius of hole are different in the second specimen.One of them is 1 mm, and the other one is 2 mm.Meanwhile, the size of bridge between two hole are different.The former is 0.4 mm, and the later is 0.2 mm.Then the numerical resultes were compared with that of the experiment to verify the validity of Gurson damage models in describing the initiation and propagation of cracks during their evolution.The results show Gurson damage model give good results to the second specimen. Because the stress triaxiality of second specimen greater than 0.4.