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鋼軌缺陷的超聲導(dǎo)波檢測研究

發(fā)布時(shí)間:2018-07-28 17:00
【摘要】:鐵路運(yùn)輸尤其是現(xiàn)在高速發(fā)展的高速鐵路線路,成為了我國交通運(yùn)輸最具代表性的產(chǎn)業(yè),已經(jīng)有許多新型的無損檢測技術(shù)廣泛使用在了尋找鋼軌的缺陷上面。研究鋼軌缺陷無損檢測的實(shí)時(shí)監(jiān)測系統(tǒng)對(duì)鐵路運(yùn)輸產(chǎn)業(yè)的可持續(xù)性發(fā)展和安全平穩(wěn)運(yùn)營是非常重要的。超聲導(dǎo)波在固體結(jié)構(gòu)中傳播,不斷的和結(jié)構(gòu)邊界相互作用,并伴隨著干涉疊加以及縱波和橫波間的模態(tài)轉(zhuǎn)換等現(xiàn)象,也就造成了超聲導(dǎo)波在彈性介質(zhì)結(jié)構(gòu)中通常出現(xiàn)多樣性的傳播模態(tài)。超聲導(dǎo)波在波導(dǎo)介質(zhì)的傳播過程中,絕大多數(shù)傳播模態(tài)都具有頻率色散特性,鋼軌作為具有非常好的聲導(dǎo)特性的固體波導(dǎo)彈性介質(zhì),可以運(yùn)用技術(shù)分析鋼軌中超聲導(dǎo)波的頻散特性來達(dá)到對(duì)應(yīng)力和斷軌等諸如此類的鋼軌狀態(tài)檢測。 首先介紹了超聲導(dǎo)波主要是研究內(nèi)容以及超聲導(dǎo)波無損檢測技術(shù)的四個(gè)模態(tài)特性的分析、模態(tài)的選擇、模態(tài)的控制和模態(tài)的分解部分。還從理論層面介紹了使用半解析有限元的方法可以計(jì)算得出各向同性均質(zhì)自由彈性結(jié)構(gòu)中超聲導(dǎo)波的頻散特性曲線。有限元方法的基本原理以及對(duì)于不同物理性質(zhì)和數(shù)學(xué)模型的問題,還對(duì)有限元方法數(shù)學(xué)建模求解計(jì)算的基本步驟作了一定的簡單介紹。然后介紹了超聲導(dǎo)波無損檢測技術(shù)的情況和大致的檢測過程。然后根據(jù)彈性波在彈性介質(zhì)結(jié)構(gòu)中傳播的運(yùn)動(dòng)方程,應(yīng)變位移關(guān)系和應(yīng)力應(yīng)變關(guān)系,計(jì)算出超聲波在無限大各向異性彈性介質(zhì)結(jié)構(gòu)中傳播的控制方程。同時(shí)介紹了一些彈性介質(zhì)結(jié)構(gòu)中的剛度矩陣的表達(dá)方程。最后簡單計(jì)算推出了超聲導(dǎo)波在各向同性的平板中的色散方程,還描述了超聲導(dǎo)波在平板中傳播的頻散曲線和導(dǎo)波結(jié)構(gòu)。 接著提出了一種通用的方法,應(yīng)用半解析有限元方法推導(dǎo)出在一般彈性介質(zhì)結(jié)構(gòu)任意截面中超聲導(dǎo)波的傳播模型。從過去的提出的半解析有限元方法模型中推導(dǎo)出在阻尼存在的粘彈性結(jié)構(gòu)中,,計(jì)算求解出能量速度曲線和衰減曲線。 最后通過有限元方法對(duì)超聲導(dǎo)波在鋼軌中傳播模態(tài)進(jìn)行了分析,對(duì)ANSYS瞬態(tài)動(dòng)力學(xué)分析基本理論做了簡要描述。通過使用有限元方法首先對(duì)平板彈性介質(zhì)結(jié)構(gòu)中進(jìn)行建模,然后擴(kuò)展到對(duì)鋼軌中超聲導(dǎo)波傳播模態(tài)研究的有限元建模。
[Abstract]:Railway transportation, especially the high-speed railway line, has become the most representative industry in China, and many new nondestructive testing techniques have been widely used to find the defects of rail. It is very important for the sustainable development and safe and stable operation of railway transportation industry to study the real-time monitoring system of rail defect nondestructive detection. Ultrasonic guided waves propagate in solid structures, interact with structural boundaries, and are accompanied by interference superposition and modal conversion between longitudinal and shear waves. Therefore, the ultrasonic guided waves usually appear a variety of modes of propagation in elastic media structures. In the process of ultrasonic guided wave propagation in waveguide medium, most of the propagation modes have frequency dispersion characteristics. Rail is a solid waveguide elastic medium with very good acoustic conductivity. The technique can be used to analyze the dispersion characteristics of ultrasonic guided waves in the rail to detect the stress and the rail breaking. Firstly, the research content of ultrasonic guided wave and the analysis of four modal characteristics of ultrasonic guided wave nondestructive testing technology, modal selection, modal control and modal decomposition are introduced. The dispersion curves of ultrasonic guided waves in isotropic homogeneous free elastic structures can be calculated by using semi-analytical finite element method. The basic principle of the finite element method and the basic steps of solving the mathematical model of the finite element method for different physical properties and mathematical models are also briefly introduced. Then the ultrasonic guided wave nondestructive testing technology and the approximate detection process are introduced. Then the governing equations of ultrasonic wave propagation in infinite anisotropic elastic media structures are calculated according to the equations of motion strain displacement and stress-strain relations of elastic waves propagating in elastic media structures. At the same time, the expression equations of stiffness matrix in some elastic media structures are introduced. Finally, the dispersion equation of ultrasonic guided wave in isotropic plate is derived, and the dispersion curve and structure of ultrasonic guided wave propagating in the plate are also described. Then a general method is proposed, and the propagation model of ultrasonic guided waves in arbitrary sections of elastic media structures is derived by using semi-analytical finite element method. In the viscoelastic structure with damping, the energy velocity curve and the attenuation curve are calculated from the semi-analytical finite element method model proposed in the past. Finally, the mode of ultrasonic guided wave propagation in rail is analyzed by finite element method, and the basic theory of ANSYS transient dynamics analysis is briefly described. The finite element method is used to model the elastic medium structure of a flat plate, and then the finite element method is extended to the finite element modeling of the ultrasonic guided wave propagation mode in the rail.
【學(xué)位授予單位】:武漢紡織大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2014
【分類號(hào)】:U216.3;TB559

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