M JAMALI - Ph.D. Student,School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran
B Mohammadi, - Associate Professor,School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran
M.M Shokrieh, - Professor Composites Research Laboratory, Center of Excellence in Experimental Solid Mechanics, School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran

The damage-entropy model is a new approach for predicting the fatigue life of laminated composites based on the concept of thermodynamic entropy. The objective ofthe present paper is to predict the fatigue life of off-axis unidirectional composites based on the damage-entropy model. In this paper, the fracture fatigue entropy (FFE) wasconsidered as the fatigue failure criterion for the life prediction of off-axis unidirectional composites under fatigue loading conditions. The FFE is the accumulated entropygeneration up to the final failure during the fatigue process. The damage-entropy model considers the temperature evolution during the fatigue life, and the dissipated heat due to the viscoelastic property of the matrix. In the present paper, the proposed model is validated by investigating the fatigue behavior of unidirectional off-axis carbon/epoxy AS۴/۳۵۰۱-۶ composites under tension-tension cyclic loading. Results show that the fatigue life prediction by the damage-entropy model is in good agreement with the experimental data.

Fatigue life prediction; Off-axis composites; Damage-entropy model; Fracture fatigue entropy