Pulse Compression Technology And Its Application In Forging Inspection By Using Phased Array

Since the size and the volume of most forgings is very large, and their shape andproduction process is complex, so it’s easy to produce defects of various propertiesduring the production process, such as white dots and cracks. The defects willseriously affect the performance of the forgings, threatening the reliability and safetyof their use, and can greatly reducing their service life. Therefore it has greatsignificance to study the defect detection method for a forging. For the present SNRand the time resolution of the imaging signal is poor, here the passage is mainly studythe pulse compression technology and the high precision imaging method ofultrasonic phased array, the main work includes:(1) The pulse compression technology. Filter processing is performed on theultrasonic echo signals by using the wiener filter and autoregressive spectral analysismethod. Then the method is applied to the nondestructive test of plate structure.Meanwhile the effect of autoregressive order and the select of frequency windowduring the signal processing are investigated.(2) The study of post-processing of the full matrix of ultrasonic transmit-receivearray data. By using the processing algorithms, the paper realized the plan B-scan,focused B-scan, sector B-scan and the total focusing method, and then use the API toevaluate several imaging methods, the total focusing method is optimal. Then thecorrected TFM method is investigated by using both test and simulation data; at lastthe pulse compression technology is applied on the total focusing method andimproved the imaging quality.(3) The application of ultrasonic phased array technology in the forging detection.In this section, we test the actual large forgings by using the ultrasonic phased arraytechnology, analyzed the type of the defect in the forging by analyzing the A-scanwaveforms and the sector scan results. Then the forging anatomical experiments areconducted, the results of low magnification verify that the flaw detection and thedefect type analysis is effective. On this basis, to verify the validity, the total focusingmethod is applied on the forging test.