Continuum Damage Approach to Asphalt Concrete Fatigue Modeling

Abstract

A nonlocal damage model is proposed to predict the behavior of pavement fatigue cracking. This constitutive relation has been implemented in a finite-element code, along with a self-adaptive jump-in-cycle procedure for high cycle fatigue computations. Strain localization analysis shows that during uniaxial fatigue tests, bifurcation due to strain softening occurs much later than in monotonic tests. The incorporation of an internal length into the constitutive model is advocated since the model should encompass loading histories with very different amplitudes of cycles, in which localization may still occur. The influence of the internal length on the fatigue life of bending beams is also investigated. Calibration of the damage model is performed after thermal effects have been evaluated and accounted for in a simplified way, uncoupled to damage. Parameter identification is performed in bending and uniaxial tests. The resulting calibrated constitutive relation is found to yield a good description of several different uniaxial tests.