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Detection and Surveillance of the Damage for Particle Reinforced Metal Matrix Composites by Ultrasonic Method

Author: YangZhiGuo
Tutor: LongShiGuo
School: Xiangtan University
Course: Physical Electronics
Keywords: Non-destructive Evaluation Particle reinforce metal matrix composites Wavelet analysis Correlation analysis
CLC: O346.5
Type: Master's thesis
Year: 2008
Downloads: 67
Quote: 2
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Abstract


Because of the convenience, speediness and non-destruction, the ultrasonic testing is an important method for detection and surveillance of damage. Particle reinforced metal matrix composites (PMMC) is an important structural material for its excellent performance. In this paper, the research on PMMC under different loads is investigated by ultrasonic detection and acoustic emission (AE) methods.The evolutions of ultrasonic detection, AE and PMMC are firstly presented. Then the damage of the materials is determined. After that, the damage of PMMC under tensile load and fatigue load were studied by ultrasonic method. The ultrasonic signals were processed with wavelet and correlation methods. The damage of PMMC under tensile loads in room and high temperature were surveillanced by AE method. The results are following.(1) With the increase of tensile load, the damage parameter increases. The damage parameter increases slowly when tensile load less than 300MPa, but when tensile load exceeds 300MPa, the damage parameter changes a lot. The ultrasonic signal traveled in the specimen damaged induced under different tensional load was analyzed by correlation method. With the increase of tensile load, the correlation coefficient decreases. The fracture section morphologies of PMMC under tensile load are observed by SEM. There are many concaves in the metal matrix. Therefore the damage evolution can be concluded. The initial damage is induced by void nucleation, growth and subsequent coalescence in the matrix or interface separation.(2) The ultrasonic signal traveled in the specimen damaged induced by fatigue was analyzed by correlation method, wavelet and frequency-analysis method. It can conclude that with the increase of fatigue times, the damage parameter increases. The damage parameter increases quickly at the beginning of fatigue, and then it increases slowly.The ultrasonic signal traveled in the specimen damaged induced by fatigue was analyzed by correlation. With the increase of fatigue times, the correlation coefficient decreases. When the fatigue times less than 50, the correlation coefficient changes quickly, but when the fatigue time exceeds 50, the decrease of correlation coefficient becomes slowly. The ultrasonic signal propagated in the specimen contains a series of frequencies. As the fatigue of the specimen becomes more severe, the ultrasonic signal that traveled in the specimen contains more and more frequency component.(3) The acoustic emission of PMMC under tensile load and three points load in room and high temperature were studied. It is found that much AE events were found before PMMC yield. The evolution of the damage under room temperature and high temperature are different. In the high temperature, the AE events and the amplitude are smaller than that of in room temperature.In this paper, the relationship between properties of PMMC and acoustic parameter of ultrasonic is studied. It provides reference value to make good use of PMMC safely and optimize design of PMMC, as well as accumulates data and research method by ultrasonic non-destructive Evaluation.

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CLC: > Mathematical sciences and chemical > Mechanics > Solid Mechanics > Strength theory > Damage theory
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