Acoustic Emission Characteristics Of FRP Composite Material Damage

Composites was widely used in various aspects for its high specific tenacity,high specific modulus,high tolerance of damage and designable performance. However, during composite materials processing can easily produce composites defects,such as slack,cracks,pores and ill-cohesion of the interface. The factors such as loading,mechanical damage,fatigue, creep and other complex conditions which composites endured in the process of active service may cause the damage of the composite,and the serious damage will lead the entire failure of the material which may cause significant economic losses. Therefore it is important to research on the damage and performance prediction of composites at present.It is a tried and true approach to study on the damage evolutive rule and fracture mode in tensile process of FRP composites by acoustic emission technique, and the feature of damage and fracture can be reflected clearly and directly. This article is based on FRP composite materials as the research object, the damage mechanisms of self-reinforced polyethylene composites laminates being subjected to tensile loading were investigated by acoustic emission technique and a scanning electron microscope technique in this study, discussing FRP composite materials several stages of tensile fracture under tensile loading. And compare with the feature and fracture mechanism of some typical Ply stacking Angle composites,and summarize the approximation relations of fiber Ply stacking Angle,tensile strength and acoustic emission behavior in tensile rupture process of composites.The AE signals of composite material are complex and mostly unsteady,so it is difficult for the traditional method to achieve the desired results, using wavelet de-noising method can solve the problem. Wavelet transform has a good capability of de-noise the AE signals, and it will not occur the edge of leak phenomenon. It is effective for frequency analysis method to distinguish the different mechanisms of composite materials injury. At the same time, results from this study revealed that the acoustic emission technique is a viable and effective tool for identifying the damage mechanisms in the composite materials.