傳統上模擬裂縫開展問題的作法多採取凝聚元素鋪設於裂縫開裂沿線上，此方法預先鋪排大量特殊元素使其後續產生開裂後的不連續面，所產生的計算成本相對高；相場法的出現提供了以連續場去近似裂縫面的不連續，而且相場模擬中不預設裂縫開展方向，對於不能確定裂縫開展方向的問題，省去了鋪排大量凝聚元素與預設方向的困擾。
本文運用特定相場分佈形式，配合材料弱化之二次遞減函數或指數型遞減函數在有限元素軟體中建立相場模型，分析脆性裂縫開展問題。分別模擬中央裂縫問題及三點彎矩破壞試驗，並討論載重–位移曲線和裂縫開展過程受到遞減函數形式與其中參數值，裂縫附近元素大小等變因的影響。再以相場模擬不對稱三點彎矩破壞試驗預測開展情形與實驗數據比對。

Different than the traditional cohesive zone model used to simulate the crack propagation, a phase field model approximates the discontinuous crack faces by a continuous phase field. Instead of setting up the cohesive elements along the expected crack path, phase field model can be applied to the fracture problem without knowing the direction of crack propagation in advance.
We applied the phase field model in FEM software to simulate the fracture problems including a center crack under tensile load, a three-point bending fracture test and an asymmetric three-point bending fracture test. A specific phase field distribution and two types of degradation function were used in our model, and how they affect the simulations were also discussed. The phase approximated crack for an asymmetric three-point bending fracture test is compared to experimental data.

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