本文模擬一具有邊緣初始裂縫之異向性平板試片受垂直於裂縫方向之疲勞負載所造成之裂縫延伸情況。
考慮裂縫於穩定成長下之實際延伸情形，每一週次負載使裂縫沿一定方向延伸。模擬中裂縫依循所假設之方向選取機率規則隨機成長，而裂縫成長速率則簡化由該成長方向裂縫之第Ⅰ型應力強度因子決定，由初始裂縫成長至達到臨界不穩定成長之裂縫。

其中，決定應力強度因子與裂縫成長量關係之式由文獻所推導而來，可充份地描述裂縫穩定成長之特性，對於該式之材料係數，本文定義一誤差函數以試誤法由實驗數據求取，直接反應實際的材料疲勞性質。另一方面，在裂縫成長方向的選取規則上，本文採用較文獻上更為精緻的選取函數，提昇了模擬的準確性。

由本模擬模型之建立，該型態幾何與負載下之疲勞裂縫問題可經由數值計算模擬其發展，由各組參數化條件進行模擬的結果可得參數個別對於疲勞週次之影響。另一方面，滾軋材料於方向上的抗疲勞差異性在本文中亦被模擬比較，可提供設計時選擇板材方向之參考。

本文主要以增加模擬的精確性為目標，使得模擬方法在破裂問題上增加其應用價值。

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