Numerical Simulation of Two-Point and Four-Point Bending Fatigue Tests on Asphalt Mix Using Intrinsic Material Parameters Calibrated from Digital Image Correlation Data

According to current interpretations, fatigue properties of asphalt mixes vary depending on the type of test performed. The aim of this work is therefore to model and simulate numerically different fatigue tests using intrinsic material parameters. The modeling of the fatigue tests proposed in this work is based on linear elastic fracture mechanics and the Paris law. This modeling is used to simulate four-point bending (4PB) and two-point bending (2PB) fatigue tests performed on the same asphalt mix using similar values of the model parameters. The results obtained are satisfying and attest that the same set of parameter values would be able to predict the mechanical response of different tests. 2PB fatigue tests are then carried out on a sand asphalt with digital images acquisition. The images recorded are processed by Digital Image Correlation (DIC) to provide the displacement and strain fields in the material as well as the crack paths. These are found not systematically identical for different samples of the same material undergoing similar test conditions because of heterogeneity of the material at local scale. The 2PB fatigue tests are then numerically simulated considering the crack paths determined from the DIC data. The results show that the scatter of the fatigue curves can be explained in part by the difference in crack path observed for the different samples.