Spectrun Analysis Of Ultrasonic Testing And Application Of Flaw Recognition

Ultrasonic spectrum analysis is the ultrasonic testing technology which puts into use the spectrum analysis theory and approach. Generally speaking, simple and primitive ultrasonic signals can provide relatively limited information and therefore are far from being capable of satisfying the need of sonic analysis and feature recognition which the help of necessary processing and research. Through recognition of domain function chart as well as feature extraction and analysis, more useful information can be obtained to instruct the engineering application.This essay is to study under background of the project "ultrasonic scan testing system development for aircraft workpiece" ultrasonic automatic testing, ultrasonic signal processing in nondestructive evaluation, ultrasonic spectrum analysis theory, and approach as well as its application in relating workpiece-defection recognition. The six chapters of this essay are as follows:Chapter 1 is the preface which introduces the background and necessity of subject research, and thereafter describes the limitation of traditional ultrasonic flaw-detecting technique in addition to the current condition and significance of signal processing and spectrum analysis of testing technology in China and abroad. And along with the model engineering project the research target of this essay is then proposed to offer a general framework of the dissertation.Chapter 2 is to establish theoretical model of ultrasonic spectrum analysis system and to adopt in accordance with subject demands the reasonably designed practical system of ultrasonic spectrum analysis on the basis of regular ultrasonic testing system formation analysis. The calculation formula are attained aiming at the flaw spectrum features of different shapes and sizes as well as theoretical analysis of mutual function between ultrasonic field and flaws. Theory of sonic radiation field is adopted to define the flaw classification on the basis of confirmation of various flaws indicated on the frequency features.Chapter 3 provides primary principles and approaches of ultrasonic spectrum analysis in accordance with features of ultrasonic testing signals. With feature of ultrasonic testing robot, models of system spectrum analysis as well as demands of system software as the foundation, a general introduction of approaches of spectrum analytic processing designs is to offered. We also illustrate in this chapter the general demands, key techniques, chief calculation approaches and realization ofcorresponding software data structures.Chapter 4 introduces the research of application and techniques of ultrasonic spectrum features on the analytic system which has been constructed. Spectrum feature analysis of the transducer apparatus is also conducted with this approach and thus achieves the best testing status. Through the study of sonic adjustment of structure features, analytic examples of metal workpiece defect features are provided.Chapter 5 is to discuss spectrum analytic theory and application of void content measure testing of carbon fibre reinforced plastics in order to analyze and discuss spectrum experiment of it. The impact of void shape on ultrasonic attenuation is discussed as well.Chapter 6 is to analyze error sources and limitations of ultrasonic spectrum analysis and there by suggest the applicable approach to the research work, primary conception of the following research is being advanced.