| The main material of AC313helicopter fuselage is honeycomb sandwichcomposite. Honeycomb sandwich composite materials used for multilayer structureand anisotropy. In the process of research stress damage, conventional NDTmethods are difficult to monitor the inside structure change of materials. The methodof Acoustic emission is acquisition and processing acoustic emission signal in theprocess of loading to evaluate the development of internal damage and damage mode,then predicting ultimate bearing capacity of the material.This paper chooses AEwin Acoustic emission produced by the physicalacoustics corporation monitor the compression process of honeycomb sandwichcomposite for the AC313helicopter components. Simulating and analysis the stressdistribution of honeycomb sandwich composite materials in the process of loading byfinite element software. According to the results of simulation analyse the process ofmaterial damage. Through parameter analysis, waveform analysis and clusteringanalysis extract the Acoustic emission signal characteristic.Parameter analysis shows that at the beginning of the load, rise time andduration of acoustic emission signal is short, ringing counts are less, average energy isrelatively low; In the middle of the load, rise time and duration increased, the averageenergy has increased obviously; In the late loading, the signal is main big ringingcount, large energy, and long duration one. Waveform analysis results are as follows.During the process of jig friction and fibre friction, the energy is generally low, andthe energy is average, the frequency is low, high frequency signal is less. During theprocess of matrix cracking and crack initiation, the l energy increased, the frequencyis low, high frequency signal increased. During the process of fibre breakage, theaverage energy is larger, contains a lot of high frequency signal. K-means clusteranalysis shows that the Acoustic emission signal in the process of compression isdivided into three categories. Analysing three kinds of signal characteristics find outfollow conclusions. Cluster1signal exists in the whole process of compressionloading. Assembly technology clamp start to extrusion and friction with the sample.With the increase of load, the inside fibre of honeycomb sandwich composite isrubbing. Cluster2signal started in the middle of the load，for a sign of deformation and the honeycomb core delamination damage. Cluster3signals appeared in the lateloading stage, for honeycomb sandwich composite material plate fibre fault signal.This paper obtained the relations of honeycomb sandwich composite acousticemission signals and stress damage. Through stress damage signals to identifydamage types, design damage criterion, provides the theoretical basis and importanttest analysis data for the design of helicopters. |
