本文選題：激光超聲　切入點(diǎn)：金屬鋁　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：激光超聲檢測(cè)技術(shù)是近年來(lái)新興的一種無(wú)損檢測(cè)方法,它具有非接觸、頻帶寬、分辨率高、適合惡劣環(huán)境等優(yōu)點(diǎn),特別適用于金屬表面缺陷的檢測(cè)。本文從數(shù)值模擬和實(shí)驗(yàn)兩方面展開(kāi)對(duì)激光超聲技術(shù)應(yīng)用于金屬表面缺陷檢測(cè)的研究,研究的主要內(nèi)容有：采用有限元法數(shù)值模擬了脈沖激光在各向同性鋁板材料中產(chǎn)生超聲波的物理過(guò)程,分析了激光參數(shù)對(duì)超聲場(chǎng)的影響,結(jié)果表明改變激光光斑半徑和激光脈沖上升時(shí)間可對(duì)超聲場(chǎng)產(chǎn)生較大影響,進(jìn)而可以通過(guò)調(diào)節(jié)激光脈沖的參數(shù)來(lái)控制所激發(fā)的超聲場(chǎng)。之后分析了激光超聲作用于無(wú)缺陷鋁板激發(fā)各種模態(tài)超聲波的傳播規(guī)律及特點(diǎn),研究了激光超聲與帶表面缺陷的鋁板材料的相互作用,分析了缺陷對(duì)超聲波傳播的影響,得到通過(guò)表面波對(duì)表面缺陷進(jìn)行檢測(cè)以及粗略定位的方法。利用激光超聲檢測(cè)系統(tǒng),對(duì)人工制作的帶缺陷鋁板試件進(jìn)行了檢測(cè)研究。分析了激光超聲與缺陷相互作用的反射波和透射波的產(chǎn)生原因及傳播特點(diǎn),又進(jìn)一步對(duì)比研究了反射波和透射波的傳播規(guī)律。結(jié)果表明,反射波缺陷信號(hào)的信噪比明顯強(qiáng)于透射波信號(hào)。最后分析了缺陷尺寸參數(shù)對(duì)超聲波的影響,得出了缺陷參數(shù)對(duì)超聲波信號(hào)的影響規(guī)律,實(shí)驗(yàn)結(jié)果為缺陷定位和尺寸定量分析提供了依據(jù)。
[Abstract]:Laser ultrasonic testing technology is a new nondestructive testing method in recent years. It has the advantages of non-contact, frequency bandwidth, high resolution, suitable for harsh environment, etc. It is especially suitable for the detection of metal surface defects. In this paper, the application of laser ultrasonic technology to the detection of metal surface defects is studied from the aspects of numerical simulation and experiment. The main contents of the study are as follows: the physical process of ultrasonic produced by pulsed laser in isotropic aluminum plate is simulated numerically by finite element method, and the influence of laser parameters on ultrasonic field is analyzed. The results show that changing the radius of laser spot and the rising time of laser pulse can greatly influence the ultrasonic field. Then the ultrasonic field can be controlled by adjusting the parameters of laser pulse. The interaction between laser ultrasonic and aluminum plate with surface defects is studied, and the influence of defects on ultrasonic propagation is analyzed. The method of detecting and locating surface defects by surface wave is obtained. In this paper, the causes and propagation characteristics of reflection and transmission waves of laser ultrasonic and defect interaction are analyzed. The results show that the signal-to-noise ratio of the reflected wave defect signal is obviously stronger than that of the transmission wave signal. Finally, the influence of defect dimension parameters on ultrasonic wave is analyzed. The influence of defect parameters on ultrasonic signal is obtained. The experimental results provide the basis for defect location and quantitative analysis of size.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN249;TP274

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本文編號(hào)：1572092