Micromechanics Modeling and Prediction of Stiffness Degradation Behavior of a Fiber Reinforced Polymer Nanocomposite Under Block Amplitude Fatigue Loads

摘要

The micro-mechanisms of fatigue damage initiation and growth in polymer composites lead to observable progressive degradation in global properties such as strength and stiffness. Thus monitoring stiffness degradation behavior of a composite will assist in evaluating the residual strength, stiffness and remaining fatigue life of the material. In the present investigation, the stiffness degradation behavior of a glass-fiber epoxy silica-nano-particle composite (GFRP nanocomposite) under a two step block load sequence was predicted from micro-mechanics based models. The stiffness of nanocomposite was determined from the properties of the constituent materials. To compare the predicted results, experiments were conducted on a GFRP nanocomposite. The stiffness of the specimen was monitored at regular intervals during the fatigue tests. The predicted stiffness degradation behavior of the nanocomposite under variable amplitude fatigue loads was observed to compare quite well with experiments.