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为了研究沥青混合料疲劳损伤断裂特性,应用断裂力学积分守恒定律,提出一种关于沥青混合料对称边缺口试件拉伸疲劳损伤的封闭解法,并根据有限元计算与有关试验结果的对比,确定了合适的试件缺口处应力集中系数和沥青混合料疲劳损伤特性参数,同时证明了在拉伸疲劳试验情况下所提出的沥青混合料非线性疲劳损伤模型的有效性。根据非线性有限元计算,分析了沥青混合料含缺口试件拉伸疲劳损伤开裂、裂纹扩展过程,讨论了不同阶段试件内部损伤度、拉应力的分布规律,以及它们和试件位移、疲劳寿命随预制裂纹起裂、扩展的变化规律。研究结果表明:基于疲劳损伤有限元和Paris公式的沥青混合料含缺口拉伸试件的疲劳损伤分析结果与直接拉伸疲劳试验结果基本一致,但基于Paris公式的计算结果无法反映试件在起裂和扩展初期阶段裂纹扩展速率的变化情况。
In order to study the fatigue damage and fracture characteristics of asphalt mixture, an integrated solution to the tensile fatigue damage of symmetrical notched specimens of asphalt mixture is proposed by applying the law of conservation of integral of fracture mechanics. Based on the comparison between the finite element calculation and the related test results, The stress concentration factor and the fatigue damage parameters of asphalt mixture were tested. At the same time, the validity of the proposed nonlinear fatigue damage model of asphalt mixture under tensile fatigue test was proved. According to the nonlinear finite element calculation, the tensile fatigue damage cracking and crack propagation of asphalt mixture notched specimens are analyzed. The internal damage and tensile stress distributions of the specimens at different stages are discussed, and their relationships with specimen displacement, fatigue Life expectancy with pre-crack initiation and propagation of the law of change. The results show that the fatigue damage analysis results of asphalt mixtures with notched tensile specimens based on fatigue damage FEM and Paris formula are basically consistent with the results of direct tensile fatigue tests. However, the calculation results based on the Paris formula can not reflect the experimental results Crack and expansion in the early stage of crack growth rate changes.