激光超声对铝合金材料内部缺陷检测的实验研究

摘要激光超声检测技术是利用激光脉冲照射样品表面，激发出超声波，并利用光学方法对超声波进行检测，从而实现对样品进行无损检测的一种方法。它随着现代科技和工业的发展，应用范围也越来越广。激光超声检测技术由于能够在短时间内不接触物体进行激光激励，适合于环境复杂的检测环境，并具有极强的抗干扰能力。所以，激光超声技术在材料缺陷和性能的无损检测中发挥了超声检测的优势。67120

本文对激光超声技术进行阐述，并介绍了激光超声检测技术的具体应用。在此基础上，着重介绍了激光产生超声的激发机理，包括热弹激发和融蚀激发；并对横波、纵波和声表面波的运动方程和方向性做了具体分析。通过体波透射法对缺陷进行定位，结合体波反射法检测缺陷深度。

毕业论文关键词激光超声热弹性激发体波透射法体波反射法

毕业设计说明书（论文）外文摘要

Title Experimental study of laser ultrasonic detection of

internal defects of aluminum alloy material

Abstract

Laser ultrasonic detection technology is the pulse irradiates the sample surface by using laser ultrasonic, inspire, and to detect the ultrasound using optical methods, so as to achieve a nondestructive detection method for sample. It is with the development of modern science and technology, more and more wide range of applications. Laser ultrasonic detection technology because in a short time can not contact with the object of laser excitation, suitable for complex testing environment, and has a strong anti-interference ability. So, the laser ultrasonic technique play an ultrasonic detection advantage in nondestructive detection of material defects and performance of.

This paper elaborates on the laser ultrasonic technique, and introduces the application of laser ultrasonic detection technology. On this basis, emphatically introduces the laser generated ultrasound excitation mechanism, including the thermoelastic excitation and thermal erosion excitation; and makes a concrete analysis equations of motion and the direction of shear wave, longitudinal wave and surface acoustic wave. The positioning of defects by body wave transmission method, combined with the defect depth of reflected wave testing method.

Keywords Laser ultrasonic Thermoelastic excitation Body wave transmission method Body wave reflection method

1 绪论 1

1.1 激光超声的概述 1

1.2 激光超声的检测应用 2

1.3 本课题的工作 3

2 激光超声检测缺陷的理论基础 5

2.1 激光超声的激发机理 5

2.2 主要的波形 6

3 激光超声检测缺陷 11

3.1 激光超声检测缺陷的方法 11

3.2 检测结果与讨论 13

结论 21

致谢 22

参考文献 23

1 绪论

在影响材料、构件质量和安全性等诸多因素中，内部缺陷的危害性极大，而隐藏在材料和构件中的缺陷往往又是致命裂纹的起点，更具隐蔽性和危险性，所以作为无损检测技术的一个重要方面，就是对材料和构件的内部缺陷进行检测。在缺陷检测中，常规的无损检测方法是磁粉检测和射线检测在磁粉检测中，不但有检测对象的限制，还有灵敏度等许多问题；而射线检测对人体存在危害。激光超声检测技术，以其非接触式测量，光声转换效率高，高准确度和高分辨率等优点受到国内外的关注。激光超声对铝合金材料内部缺陷检测的实验研究:http://www.751com.cn/wuli/lunwen_75210.html