焊縫無(wú)損探傷導(dǎo)波探頭設(shè)計(jì)
Design on ultrasonic weld-guided probe

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摘要 焊接結(jié)構(gòu)是巨大工業(yè)財(cái)富的組成部分，如不能對(duì)焊縫缺陷進(jìn)行定期檢查及有效的安全評(píng)定勢(shì)必會(huì)造成重大惡性事故，給企業(yè)帶來(lái)重大的經(jīng)濟(jì)損失。焊接結(jié)構(gòu)的安全性直接影響著工業(yè)生產(chǎn)的效率和安全。如何保證焊縫安全，實(shí)現(xiàn)對(duì)焊縫內(nèi)部缺陷的精確定位、定量和定性分析及缺陷評(píng)定，是迫切需要解決的課題。
傳統(tǒng)的超聲檢測(cè)方法由于檢測(cè)深度大；缺陷定位準(zhǔn)確，檢測(cè)靈敏度高；成本低，速度快，對(duì)人體無(wú)害以及便于現(xiàn)場(chǎng)使用等特點(diǎn)，而被廣泛應(yīng)用。但是這種方法對(duì)被測(cè)焊縫逐點(diǎn)檢測(cè)，相對(duì)于長(zhǎng)距離焊縫檢測(cè)效率較低，不適用于大規(guī)模焊接結(jié)構(gòu)的檢測(cè)。超聲導(dǎo)波檢測(cè)是近年來(lái)發(fā)展起來(lái)無(wú)損檢測(cè)新方法，一次掃描內(nèi)即可測(cè)量整個(gè)厚度范圍內(nèi)包括內(nèi)部和表面的所有缺陷，并且可同時(shí)實(shí)現(xiàn)缺陷定位與尺度檢測(cè)。超聲導(dǎo)波檢測(cè)雖然在很多大型長(zhǎng)輸結(jié)構(gòu)如管道、鐵軌等得到了廣泛的應(yīng)用，但在大型板料結(jié)構(gòu)焊縫缺陷無(wú)損檢測(cè)的應(yīng)用仍停留在理論和實(shí)驗(yàn)室階段。
本課題在現(xiàn)有橫波探頭基礎(chǔ)上，從研究大型板材焊縫的結(jié)構(gòu)形式、導(dǎo)波在焊縫中的傳播特性及其與焊縫缺陷的相互作用機(jī)理入手，研究并設(shè)計(jì)焊縫檢測(cè)超聲導(dǎo)波傳感器及其固定、耦合系統(tǒng)，從而真正滿足焊縫無(wú)損檢測(cè)的需要，為焊縫缺陷的特征導(dǎo)波無(wú)損檢測(cè)提供保障，對(duì)促進(jìn)大型板料結(jié)構(gòu)焊縫無(wú)損檢測(cè)的應(yīng)用研究具有重要意義。

關(guān)鍵詞： 超聲導(dǎo)波；無(wú)損檢測(cè)；焊縫缺陷；探頭；壓電式

Design on ultrasonic weld-guided probe
ABSTRACT
The welding structure is a huge part of the industrial wealth. If we cannot inspect the weld defects and cannot give the efficient safety eva luation regularly, it will result in major accidents and brings huge pecuniary loss to the company. The safety of welding structures directly affects the efficiency and safety of industrial production. How to ensure the safety of the welding structure and to achieve precise positioning, quantitative and qualitative analysis of internal defects of weld and how to eva luate defects are the urgent problem to solve.
Because of larger depth of detection, accurate defect locating, high detection sensitivity, low cost, fast speed, harmless to the human body and convenient field use etc, the traditional ultrasonic detection method is widely used by all of us. But this method measure the weld detection point by point, it has a low efficiency with respect to the long distance detection. It is not applicable for large-scale detection of welding structure. Ultrasonic guided wave detection is a new method in nondestructive testing that developed in recent years, it can measure all internal and surface defects throughout the thickness range by a scan and it will also realize the defect location and scale detection by the same time. Although it is widely used in long distant detection such as pipeline and rail, the application of Ultrasonic guided wave detection in large sheet structure of weld defects is still stay in the stage of theory and laboratory.
My course is based on the shear wave probe, from the structural form of large sheet weld and the mechanism of interaction of the propagation characteristics of the guided waves in the weld and weld defects, research and design ultrasonic guided wave sensor of the welding seam detection, and its fixed and coupling system to provide protection for the characteristics of welding defect for wave nondestructive testing. It is of great significance to promote the application of large sheet structure weld NDT.
Key wards: Ultrasonic guided wave, Non-destructive testing(NDT), Weld defect, Probe, Piezo-electric

目 錄
摘要 iv
ABSTRACT v
第一章 緒論 1
1.1課題研究目的和意義 1
1.2 國(guó)內(nèi)外研究現(xiàn)狀 3
1.2.1 現(xiàn)有焊縫檢測(cè)方法 3
1.2.2 超聲導(dǎo)波在焊縫檢測(cè)中的研究及應(yīng)用 4
1.3課題主要研究?jī)?nèi)容及論文框架 6
第二章 超聲導(dǎo)波理論概述 8
2.1超聲導(dǎo)波概念 8
2.2超聲導(dǎo)波的傳播特性 8
2.2.1超聲導(dǎo)波的群速度和相速度 9
2.2.2導(dǎo)波多模態(tài)性及頻散現(xiàn)象 9
2.3焊縫特征導(dǎo)波 10
2.4本章小結(jié) 10
第三章 探頭選型及結(jié)構(gòu)設(shè)計(jì) 11
3.1探頭類(lèi)型選擇 11
3.2探頭結(jié)構(gòu)及設(shè)計(jì) 12
3.3本章小結(jié) 13
第四章 壓電晶片 14
4.1 壓電材料選擇及設(shè)計(jì) 14
4.1.1壓電效應(yīng)與壓電材料 14
4.1.2壓電陶瓷的性能參數(shù) 15
4.2壓電陶瓷的振動(dòng)模式 17
4.3激勵(lì)波頻率選擇 17
4.3.1 基礎(chǔ)理論分析 17
4.3.2 實(shí)驗(yàn)設(shè)備 20
4.3.3 實(shí)驗(yàn)方法 21
4.3.4 實(shí)驗(yàn)數(shù)據(jù)記錄 22
4.3.5 總結(jié)分析 25
4.4壓電陶瓷的參數(shù) 25
4.4.1壓電陶瓷型號(hào) 25
4.4.2壓電陶瓷的尺寸 26
4.5本章小結(jié) 27
第五章 探頭固定方式及耦合方式 28
5.1探頭夾具設(shè)計(jì) 28
5.2探頭耦合方式 30
5.3本章小結(jié) 31
第六章 實(shí)驗(yàn)及結(jié)果分析 32
6.1 焊縫導(dǎo)波檢測(cè)系統(tǒng) 32
6.2 激勵(lì)接收實(shí)驗(yàn)及結(jié)果分析 32
6.3 缺陷檢測(cè)實(shí)驗(yàn)及結(jié)果分析 34
6.4 本章小結(jié) 35
第七章 總結(jié)與展望 36
7.1總結(jié) 36
7.2展望 37
致謝 38
參考文獻(xiàn) 39