Low cycle fatigue of composite laminates: A damage-mode-sensitive model

Low cycle fatigue (LCF) behavior of composite laminates is investigated along with the associated micromechanical damage. At the ply level, fatigue damage is described by a damage-mode-sensitive model, which is based on a family of S-N curves that are tailored for various types of damage. Since the LCF conditions may involve high loads reaching up to 90% of the material ultimate-strength, the S-N curves reflect unique LCF features such as non-cyclic and bi-linear corrections due to high property-degradation rates. The LCF characterization of laminates is based on authors' previous research and other relevant studies. The proposed fatigue model is implemented in a laminate and finite element analysis, and a case of a notched laminated plate is analyzed to examine accumulation of fatigue damage at the ply level in the plate. The effective fatigue-damage is predicted by the new fatigue model and compared with experimental results.