沥青混合料疲劳过程的损伤力学分析

Damage Mechanical Analysis for Fatigue Failure Process of Bituminous Mixtures

采用损伤力学方法研究沥青混合料的疲劳失效问题。针对悬壁梁弯曲疲劳试件，推导出疲劳过程中应力场、损伤场和疲劳裂纹形成寿命的工程封闭公式。根据沥青混合料特点，提出一种模拟疲劳裂纹扩展的特征单元失效模式，从而将疲劳裂纹形成与扩展两个阶段统一用损伤力学理论进行描述和分析。本文对沥青混合料试件的疲劳裂纹形成寿命与扩展寿命分段进行了预测，还对疲劳过程中刚度衰减及位移幅值的演化过程进行了数值模拟计算。理论预期与实验结果吻合良好。

This paper studies the fatigue failure of bituminous mixtures based on the conti nuum damage mechanics. For the problem of cantilever fatigue failure of bitumino us mixtures, the evolution equations of stress, strain and damage fields are der ived, and the engineering closed solution of fatigue crack initiation life is ob tained. A characteristic element failure model is developed to predict the fatig ue crack propagation life based on the damage characteristics of bituminous mixt ures. The description and analysis of two periods in fatigue process (crack init iation and propagation) are unified into the damage mechanical framework. The cr ack initiation and propagation lives are predicted respectively. The stiffness a ttenuation and displacement evolutions during fatigue damage process are calcula ted. The theoretical predictions are in good agreement with the experimental res ults.