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摘要：激光超声检损技术是近年来发展飞速的一项广泛用于工业化生产的保证产品质量的重要方式，随着激光技术水平的日新月异，激光超声检损技术也在向新的台阶迈进。本文从激光超声激光和检测技术入手，简述了激光超声的发展历程，着重关注了激光超声有限元模拟研究进展。分析了激光超声的激发机制和激光超声检测材料内部缺陷的原理，依据检损原理，用有限元模拟软件模拟激光超声在材料中的传播，研究了激光激发超声的各种性质，在增加约束层的情况下探索了不同尺寸的缺陷对超声波信号的不同影响，并且分析了x方向的位置；在上下表面为自由边界的情况下，探索了气孔缺陷z方向的位置。最后通过缺陷材料超声信号和完好材料超声信号的对比，可以评估材料缺陷的位置和大小，完成对内部气孔缺陷的模拟检测。21759
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关键词 激光检损 内部缺陷 模拟检测
毕业论文设计说明书（论文）外文摘要
Title The Simulation Research on Laser Ultrasonic Detection of Defects Inside the Material Pores
Abstract
Laser ultrasonic impaction techniques developed in recent years is an important way to ensure that products are widely used in industrial production quality, with the changing level of laser technology, the ultrasonic inspection techniques are stepping forward . This text starts from laser and laser ultrasonic detection technology, introduces the development process of laser briefly ,mainly focus on the research progress of the finite element simulation of laser ultrasonic. Its analysis is about the mechanisms and principle of excitation laser ultrasonic detection of material laser ultrasonic, according to the principles, it uses finite element simulation to simulate laser ultrasonic propagation in the material which studies various properties of laser excitation of ultrasound to explore effects that different depths and different sizes of defects on ultrasonic propagation. Finally, by comparing the ultrasound signal of defected material with the integrity of the material ultrasound signal, we can assess the position and the size of material defects ,thus, to finish the testing of defects of the internal porosity .
Keywords Laser detection loss Internal defects Analog detection
目录
1绪论 1
1.1课题的研究背景和意义 1
1.2激光超声检损的发展进程 2
1.2.1激光超声激发技术的发展进程 2
1.2.2激光超声检测技术的发展进程 3
1.3激光超声的有限元模拟的研究发展 4
1.4本文的主要工作 5
2激光超声无损检测原理 6
2.1激光超声激发机制 6
2.2各项同性弹性介质中的超声波 6
2.3热弹机制下激光超声的方向性 8
2.4激光激发超声的位移场 9
3激光超声检测内部缺陷的有限元模拟 11
3.1建模 11
3.1.1热弹性原理 11
3.1.2激光作用的力函数 12
3.1.3时间步长与单位长度的选取 12
3.2有限元模拟结果分析 13
3.2.1激光激发超声的方向性分析 13
3.2.2对心检测判断缺陷大小以及x方向的位置 14
3.2.3同侧检测z方向的位置 15