碳纤维复合材料构件微缺陷超声评价系统研究

发布时间：2018-10-29 18:05

【摘要】：碳纤维复合材料的广泛应用,使得复合材料无损检测技术的意义更为凸显。无损检测技术是在不破坏被检测对象的前提下,直接检测产品内部缺陷,并且可在产品的各个制造阶段使用,是产品质量控制的重要手段。但传统的复合材料超声无损检测手段对底波的依赖,使得超声波无损检测的推广出现了较大的局限性,特别是对于复杂形状和厚截面复合材料,这一问题更加突出。本文针对碳纤维复合材料超声检测信号的处理做了深入而广泛的研究,提出了基于递归分析的复合材料缺陷超声无损检测新方法,并通过试验验证了方法的有效性。具体内容包含以下几项工作:(1)详细分析复合材料缺陷超声检测技术现状及存在的问题和不足,对各种超声无损检测和信号分析方法的特点及适用情况进行了研究,在此基础上,引入基于超声背散射信号分析的碳纤维复合材料缺陷检测方法,并对背散射信号进行深入的研究分析。(2)研究递归分析相关理论,在此基础上建立起递归图与材料缺陷之间的联系。围绕超声波在复合材料中传播的非线性特性,结合碳纤维复合材料超声无损检测的现有技术以及金相观察试验,研究了超声检测信号的递归分析及缺陷特征提取方法,提出了基于超声回波背散射信号递归分析的超声无损检测方法。(3)为了更精确的获取检测信号中的信息,引入递归定量分析方法。借助碳纤维复合材料标准试块,验证了递归分析用于碳纤维复合材料超声无损检测的可行性,并选择了两个常用的递归量化分析指标:确定率和递归熵,通过曲线拟合获得了样本材料中孔隙率与量化指标之间的关系。进一步地,使用评价指标对未知碳纤维试块进行检测,并对比金相观察结果,验证递归分析能否有效用于碳纤维复合材料缺陷检测。(4)开发了一套超声无损检测软件。研究了 MATLAB和LabVIEW联合开发的方法,以此为基础开发了超声测试系统软件。软件不仅包含检测信号采集、显示以及存储等基本功能,还具有小波时频分析、谱分析、递归分析等多种检测信号处理功能。
[Abstract]:With the wide application of carbon fiber composites, the significance of nondestructive testing technology is more prominent. Non-destructive testing (NDT) is an important means of product quality control, which directly detects the internal defects of the products without destroying the detected objects and can be used in all manufacturing stages of the products. However, the traditional ultrasonic nondestructive testing method of composite materials depends on the bottom wave, which makes the popularization of ultrasonic nondestructive testing appear great limitation, especially for the composite materials with complex shape and thick section, this problem is more prominent. In this paper, a new ultrasonic nondestructive testing method for composite defects based on recursive analysis is proposed, and the validity of the method is verified by experiments. The specific contents include the following work: (1) the status quo, problems and shortcomings of ultrasonic testing technology for composite defects are analyzed in detail, and the characteristics and application of various ultrasonic nondestructive testing and signal analysis methods are studied. On this basis, the defect detection method of carbon fiber composites based on ultrasonic backscattering signal analysis is introduced, and the backscattering signal is deeply studied. (2) the related theory of recursive analysis is studied. On this basis, the relation between recursion diagram and material defect is established. According to the nonlinear characteristics of ultrasonic wave propagation in composite materials, combined with the existing ultrasonic nondestructive testing technology and metallographic observation test of carbon fiber composites, the recursive analysis and defect feature extraction method of ultrasonic testing signals are studied. A method of ultrasonic nondestructive testing based on recursive analysis of ultrasonic echo backscattering signal is proposed. (3) in order to obtain more accurate information from the detection signal, a recursive quantitative analysis method is introduced. The feasibility of using recursive analysis for ultrasonic nondestructive testing of carbon fiber composites is verified by using standard carbon fiber composite test blocks. Two commonly used recursive quantitative analysis indexes are selected: determination rate and recursive entropy. The relationship between porosity and quantitative index was obtained by curve fitting. Furthermore, the unknown carbon fiber samples are detected by using evaluation indexes, and the results of metallographic observation are compared to verify whether recursive analysis can be effectively used for defect detection of carbon fiber composites. (4) A set of ultrasonic nondestructive testing software is developed. The method of joint development of MATLAB and LabVIEW is studied, and the software of ultrasonic testing system is developed. The software not only includes the basic functions of signal acquisition, display and storage, but also has the functions of wavelet time-frequency analysis, spectrum analysis, recursive analysis and so on.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB302.5;TB33

【参考文献】