The Research On Analysis And Mesurement In Frequency And Acoustic Field Of Water-Logging Ultrasonic Probe

The challenge of ultrasonic nondestructive testing (NDT) focuses on fast , effective and accurate obtaining position , form and size of defect and guaranteeing the test result high reliably and sensitivity. Ultrasonic probe, whose function is launching and receiving ultrasonic wave plays an important role in the detection system. After test equipment and craft are confirmed , choice of probe becomes the main factor in guaranteeing the test result. Characteristics of probe directly restrict the performance of the whole test system. Precision and dependability of the result are uncertain if unacquainted with the characteristics before measuring .Using time-frequently analysis and visualization, the dissertion analyses probe's characteristics in frequency and acoustic field, and then constructs the system of digital spectrum analysis and acoustic field scan, measures and evaluates characteristics of frequency and ultrasonic acoustic field on the foundation of equipment " Automatically Ultrasonic Water-logging test system with C scans " developed independently.Firstly, the history of ultrasonic piezoelectricity transducer and configuration, characteristics, influence of water-logging ultrasonic probe are introduced .Then significance and content of the dissertion are given combining the project background and function to be realized .Chapter two studies the radiated acoustic field of probe in round piston type, in order to offer the theoretical foundation for analysis and mesurement of frequency and acoustic field . And how the characteristics of probe influence the test result was investigated from three respects (ultrasonic range finding in profile measurement of NDT , defect ration in AVG and orientation of real focus of immersion focusing probe in angle beam incidence) to improve localization and ration of defect test.In the guide of ASTM E 1065-99(Reapproved 2003) "Standard Guide for Evaluating Characteristics of Ultrasonic Search Unit" isued by the American Institute of material test, Chapter three puts forward the method of digital spectral analysis and ball target to measure the frequency and acoustic field of probe respectively, and the key technology such as conceiveing the model of ultrasonic digital spectral analysis,...