13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- On the other hand, if we compare the equivalent strain distribution in the outer point, inner point and the adjacent point along the edge of the holes for the two sample (see Fig.14 and 15), we can find that there does exist an obvious up rush for the equivalent strain in the initiated point from the fatigue test in the previous section compared to the surrounding edge point. Thus, it seems that the parameter, equivalent strain, can be considered to describe the new phenomena we found in the test. Furthermore, comparing the first crack propagated direction with the equivalent strain field in the outer edge of the hole; it can be found that on this direction, the equivalent strain has a maximum decrease started from the outer edge point along the direction of the crack propagation, comparing with other direction. 1 F G H F G F F G H G H F G F H F G H F E G H F F G H E G H I E H G F H G F E H H G I F I H H H G D E E F H I F H H E D F E G I H D F C D E G I E F D G H C F H H H H ED H G B C E F H I C D G F B A D E H I H H H H C AB FG I H CDE FG B C ADE I HGF B D A CE CDB A B FE G DA BCE I H F H H A DCB FEH G ABCD I DE GFCB I H EA CDF AB G EF H MN MX X Y Z A=72.764 B=218.293 C=363.821 D=509.349 E=654.878 F=800.406 G=945.934 H=1091 I=1237 NODAL SOLUTION STEP=1 SUB =16 TIME=1 S1 (AVG) DMX =11.719 SMX =1310 Fig.12, the principal stress distribution around the hole for α=15. 1 G D E F G D G F E G G E D F G E G F D G E F G D G E F G F G F E G F G D E G F F G E D C G F D E E F G E F G E C F D G C E F B G D C F G F G EF B G C FED B C D E G F CB E D F G DEG C FB CD DCB C ED G F C B D MN MX X Y Z A=297 B=499 C=699 D=899 E=1099 F=1129 G=1159 H=1189 NODAL SOLUTION STEP=1 SUB =14 TIME=1 SEQV (AVG) DMX =5.17 SMN =297.051 SMX =1189 Fig.11, the equivalent stress distribution around the hole for α=0.
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