本文探討在三維問題中，雙層異向性材料界面裂紋受應力作用下，裂紋前緣之破壞力學參數之分佈，利用有限元素法配合虛擬裂紋閉合法計算非等向性雙材料界面裂紋的三維破壞力學參數，包括應變能釋放率，應力強度因子和相位角。其中，應變能釋放率可藉由裂紋尖端元素節點上的力量和位移計算出的裂紋閉合積分式疊加求得。另外，以史磋公式為基礎理論，從得到之界面裂紋尖端的漸近應力和位移場與裂紋閉合積分式之理論關係，可求得以裂紋閉合積分式計算應力強度因子代數式，再由相位角之定義求得相位角。由於界面裂紋尖端的奇異彈性應力場具有震盪的行為，應力強度因子之值亦會隨著使用之長度單位而有震盪的行為。這個震盪的特性，會造成直接使用虛擬裂紋閉合法求解界面裂紋之應力強度因子的困難。對此問題，可藉由特定的材料特徵長度來無因次化震盪的應力強度因子，使其單位回復至(應力)×(長度)1/2。此外，對於較特殊之界面裂紋問題，包含裂紋尖端發生大範圍接觸和裂紋面受到內壓力的情况，本研究亦提出專用的公式來計算其破壞力學參數。針對於本文所提出的破壞力學參數求解數值方法，首先透過與界面裂紋問題的理論解析解比對驗證。而後，本文討論應用虛擬裂紋閉合法來分析非等向性雙材料界面上之幣狀、圓弧形邊緣或角落裂紋界面受到均勻遠端負載的問題。

The problem of a three-dimensional interface crack between two anisotropic materials is investigated by using finite element method with the virtual crack closure technique. Fracture mechanics parameters, including the strain energy release rate, the stress intensity factors and phase angles along the interface crack front are obtained by using the numerical approach. In this approach, the crack closure integrals and the strain energy release rate are first calculated from the nodal load and displacement solutions of the singular quarter-point crack-tip finite elements. A set of algebraic equations relating the crack closure integrals and the stress intensity factors is derived from the asymptotic displacement and stress fields around the interface crack tip, and is applied to determine the stress intensity factors and the corresponding phase angles. The issue of oscillating stress intensity factors associated to the bimaterial interface is overcome by normalizing the stress intensity factors to a characteristic length such that the stress intensity factors have a unit of (stress)x(length)^(1/2). Alternative procedures are also described for the cases of crack under inner pressure and crack faces under large-scale contact. Validation for the procedure is performed by comparing numerical results to analytical solutions for the problems of interface crack subjected to either remote tension or mixed loading. The numerical approach is then applied to study the problem of an anisotropic bimaterial interface crack with circular-shaped crack front. Solutions for an embedded penny-shaped crack, a semi-circular edge crack, or a quarter-circular corner crack on the interface of two cross-ply composite layers under either mode-I or mixed-moded remote loadings are presented as application examples of the proposed approach.

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