Wavelet-based Acoustic Emission monitoring of composite materials damage under quasi-static 3-point bending test

In this paper, acoustic emission (AE) monitoring with a wavelet-based signal processing technique is developed to detect the delamination process during quasi-static 3-point bending test on glass/epoxy composite materials. The main fracture mode that should be emphasized and has an effect on the residual strength of composite materials is delamination. Mode I inter-laminar fracture has received the greatest attention and various standards have been developed such as the 3-point bending test. This test simulates thrust force due to drilling process without backup plate. In this work, two types of specimen at different layups, woven [0,90]s and unidirectional [0]s, leading to different levels of damage evolution, were studied. Also, mismatching of bending stiffness between two adjacent laminate was proposed as an indicator of delamination the composite laminates subjected to bending loading. Using acoustic emission monitoring can help to detect these fracture mechanism. The obtained AE signals are decomposed into various wavelet levels. The energy distribution criterion is applied to find the more significant components which each one is in relation to intensity of delamination damage. The results show that the energy of AE signals has been concentrated in two significant components for both of the specimens. There is a difference in energy distribution of similar components of two specimens

کلیدواژه ها:

Acoustic emission ، Wavelet ، 3-Point bending ، Delamination