在包含多裂縫的結構體中，常由於接觸壓力、接觸摩擦、以及孔隙流體壓力等因素，造成裂縫表面承受非保守及非均佈的作用力，對結構整體的力學行為影響甚巨。本研究因此將針對多裂縫問題，考慮在非保守及非均佈裂縫表面力作用下，採用「M-積分」，計算裂縫生成所需之表面開裂能。研究中首先以解析方式，建構此載重狀態下M-積分結果與表面開裂能的關係，並推導確認此迴圈積分具有「與積分路徑無關」之性質；其次，再進一步以有限元素方法進行計算，討論不同裂縫表面力對結構體破壞行為及承載能力之影響。研究成果期能提供作為多裂縫問題損傷評估的依據。 In this proposed research, an energy parameter based on the concept of the M-integral is to be presented for describing the fracture behavior of a multi-cracked solid subjected to nonconservative and nonuniform crack surface tractions. By using the M-integral with a suitably chosen closed contour, one can evaluate the surface energy required for creation of the stressed cracks. Also, it is to be demonstrated that the property of path-independence holds even under the action of crack surface tractions. Therefore, the singular stress field in the near-tip areas is not directly involved in the calculation so that a complicated finite element model around the crack tips is not required in evaluation of the M-integral. The applicability of the presented approach is to be illustrated for use in assessment of material integrity due to presence of multiple stressed cracks. 研究期間：10008 ~ 10107
