Design And Study Of The Acoustic Emission System For Three-dimensional Composites

The acoustic emission technology (AE) is one kind of new dynamic nondestructive-testing technology which works to detect and analyse with special instruments at a passive-testing way. As known, when the defect or the potent defect of solid (material or some components of machines) changes, the AE signal will be detected include 3D braided composite material. This paper managed to design a sort of AE detecting system about 3D braided composite material, which is used to analyse frequency spectrum and damage evolution.Through the analysis, this paper concludes these conclusions as below: The AE signals of 3D braided composite material are mostly unsteady, which traditional AE detecting system cannot deal with well. But AE detecting system with wavelet theory takes place of it to make up the defect; the theory of wavelet has good performances on both frequency and time, and can analyse perfectly the high frequency and the low frequency of AE signals under different scales in detail, what's more, can extract the information in the AE signals; wavelet transform has a good capability of de-noise the AE signals; because virtual instruments technology ,which has bright future in the area of designing of AE detecting system, is open , flexible and easy to update and maintain, instruments are able to be defined and put together at will; the number of AE events relates to C-fiber composite material consanguineously, and damage evolution is divided into phases: initial damage period and heavy damage period.