銅膜材の屈折疲労き裂伝ぱ挙動に及ぼす圧延方向の影響 : 混合モード膜疲労試験とき裂に沿う不連続変位分布計測に基づいて

抄録

Since film materials used in electronic devise are often loaded from various directions, the crack initiated in such devises seems to propagate to various directions with bending. Therefore, it is important to consider about the fatigue crack propagation behavior under mixed-mode conditions with the crack opening and the crack sliding displacement. It this study, by using a new fatigue testing method in which the film was bonded to the cyclic loaded base plate with the inclined ellipsoidal through hole from the loading axis, the fatigue crack propagation behavior was discussed under mixed-mode conditions for a thin copper film. From the FEM analysis, stress on the film was uniform and principal stress direction was inclined from the loading axis of the base plate. Mode I and mode II stress intensity factors at the bent fatigue crack tip were calculated by using a displacement extrapolation method. As a result, the bent fatigue crack was initiated from the precrack and the crack propagation direction was almost perpendicular to the principal axis for an annealed copper film. On the other hand, the bent crack inclined to the rolling direction for cold rolled copper film with crystal grains extended to the rolling direction.