考虑松弛的沥青混合料疲劳损伤累计模型研究

根据应变控制疲劳试验的受力特点,通过分解沥青混合料应变,控制疲劳试验输入和输出响应,分析沥青混合料应变控制疲劳试验过程中的松弛现象.基于损伤力学和粘弹理论,分析由应力松弛引起的疲劳损伤和演化规律,建立考虑应力松弛沥青混合料疲劳损伤累计模型.相同条件下一组大样本疲劳试验结果与模型计算结果的对比表明,提出的损伤演化模型不仅拟合效果良好,且揭示沥青混合料在重复载荷作用下初期模量衰减的粘弹非线性本质,有利于沥青混合料疲劳研究和寿命预测.

A fatigue damage model of asphalt mixture considering stress relaxation

The cycled strain input and stress output were analyzed with the loading characteristic of the strain-control fatigue test.It was found that there was stress relaxation during the test of asphalt mixture.Based on the damage mechanics and viscoelastic theory,with the analysis of fatigue damage caused by stress relaxation and the law of evolution,a nonlinear mathematical model for evolution of fatigue damage of asphalt mixture was proposed.A comparison with the results of a set of large sample fatigue tests shows that the proposed damage evolution model not only has good fitting effect,but also discloses the nonlinear nature of viscoelasticity of asphalt mixture with initial modulus attenuation under repeated load.This has a certain theoretic significance in researches on fatigue of asphalt mixture and the prediction of fatigue life.