沥青混合料非线性疲劳损伤模型

Nonlinear Fatigue Damage Model for Asphalt Mixtures

为了研究沥青混合料的非线性疲劳损伤特性,从疲劳损伤的基本理论出发,介绍了线性疲劳损伤模型和非线性疲劳损伤模型,并基于强度-疲劳寿命方程建立了沥青混合料疲劳损伤模型,分析了沥青混合料的疲劳破坏过程;根据损伤力学理论和疲劳方程建立了沥青混合料的疲劳损伤方程,求出了损伤函数、损伤演化方程,利用该疲劳损伤方程反推得到了与疲劳加载波形、速率一致的一次荷载作用下疲劳动载强度计算模型、实际的初始应力水平计算模型及临界疲劳损伤度计算模型。结果表明:试件破坏时,材料所受到的全部损伤中包含疲劳损伤和静载损伤;沥青混合料的疲劳损伤具有非线性特性;疲劳动载强度的加载速率相关性是沥青混合料疲劳试验结果离散性的主要原因之一。

In order to explore the nonlinear fatigue damage characteristics of asphalt mixture, the linear and nonlinear fatigue damage models were introduced based on the elementary theory of fatigue damage. The fatigue damage model of asphalt mixture was established based on strength and fatigue life （S-N） equation. The fatigue damage process of asphalt mixture was analyzed. The fatigue damage equation of asphalt mixture was established according to the theory of damage mechanics and S-N fatigue equation. The damage function and damage evolution equation were deduced. The calculation model of fatigue dynamic load strength which has the same loading waveform and loading rate was deduced by the fatigue damage equation. The calculation models of actual initial stress level and critical fatigue damage degree were also obtained. Results show that the material damages at failure include the fatigue damage and the static damage. Fatigue damage for asphalt mixtures has nonlinear characteristics. One of the prime reasons which result in discreteness of fatigue test results is the correlation between fatigue dynamic load strength and loading rate.