Application Research On Damage Detection Based On Acoustic Emission Technique

When the material damage occurs, acoustic emission signals is generated because local energy is quickly released, which can be collected and analyzed to dynamicly detect the emergence and development of material defects. As a non-destructive testing technology, acoustic emission technology has great practical value in the security warning, monitoring equipment operation, which is widely used in transportation, aerospace materials, petrochemical and other fields. However, due to the complexity of the acoustic emission signal itself and vulnerability to the external environment,the acoustic emission signals with different section forms have different characteristics. In this paper, the application of acoustic emission technique in damage detection of metal materials with different preset damage is studied. The main contents are as follows:(1) This paper introduces application of acoustic emission technology in damage detection of materials and propagation characteristics of acoustic emission signals in the material, describes the main features,the development process and basic principles of acoustic emission testing technology, and discusses the acoustic emission technology in the research and application of testing metal materials.(2) In practice, the structure of non-destructive testing is often interfered by all kinds of noise. In order to ensure the accuracy of the test results, it is necessary for acoustic emission signals including noise interference to reduce noise. Common acoustic emission signal denoising methods are introduced in this paper, focusing on the application of wavelet noise reduction method, which is used for noise reduction of acoustic emission signals collected in the test.(3) During the tensile test of three different preset sectional injury specimens, acoustic emission monitoring instrument is used for the entire stretch and collect material damage acoustic emission data. A variety of analytical methods is used to analyze the characteristics of acoustic emission signal in different stages of damage evolution. According to the correlation between acoustic emission parameters, two sets of parameters with greater correlation are proposed to be applicated in the regression line slope of energy and duration to research material injury.(4) On the basis of the research of acoustic emission characteristic, this paper also made in-depth discussion in the acoustic emission technique in quantitative analysis of metal material injury and select the appropriate parameters to establish damage model of metallic materials. On the basis of the main component of the integration principle, a damage model based on main component fusion data is proposed, and model based on fusion value can do better quantitative analysis for metal injury.(5) Acoustic emission technology in the application of localization of sound source is further explored. And specimens' damage location features in different stages of stretching, the relationship between the stage positioning feature and overall positioning feature are also studied. After finite element model is established, damage characteristics of different stages of a metallic material are analyzed, and comparison is made between positioning characteristic maps of acoustic emission at different stages of injury and results of finite element simulation analysis. The paper improves the acoustic emission technique in damage identification of metal components and laid a good foundation for acoustic emission testing technology to be effectively applied to practical engineering.