Research On Fatigue Life Prediction Of Unidirectional Composite

The fibre reinforced plastic (FRP) has been widely used in the fields of aeronautics, automobile,shipping and civil industry. With the improvement of structure and design technology, more and moreattention has been paid on the fatigue damage problem of FRP. It is difficult to predict the fatigue lifeof laminated plates and complex composite structure directly. As the basic unit of laminated plates,research of the effect of off-axis angle on the fatigue behavior of unidirectional composite can providetheoretical basis for fatigue research of laminated plates and complex composite.The previous research results of the FRP were reviewed and discussed firstly in this paper.Characteristics of these researches are compared. The research methods of static strength and fatiguestrength of unidirectional composite is reviewed and compared followed. Through analysis of staticmechanical properties, component force rate is proposed to measure the contribution of componentforce to the failure of unidirectional composite, and extended to fatigue condition. Then throughanalysis of fatigue damage mechanism and relationship of component force rate with off-axis angle foroff-axis unidirectional composite, a fatigue life prediction model for unidirectional composite isproposed. This proposed model is based on the component force stress rate and the decay rate offatigue strength. To predict the unidirectional composite with off-axis angle(0°~90°), the static strengthand S-N curve of0°,90°unidirectional composite must be acquired in advance. Through comparing themodel predicting fatigue life with the experiment data, result of this model is quiet accurate. Moreover,this model need fewer material constants and is suitable for engineering application.