本文選題：有限元法 + d_(36)型壓電單晶��； 參考：《江蘇大學(xué)》2017年碩士論文

【摘要】：超聲導(dǎo)波具備傳播距離遠(yuǎn),能量損失小的優(yōu)點(diǎn),已成為當(dāng)前結(jié)構(gòu)健康監(jiān)測(cè)/無(wú)損檢測(cè)領(lǐng)域的研究焦點(diǎn)。薄板結(jié)構(gòu)中存在Lamb波和水平剪切(Shear Horizontal:SH)波,其中Lamb波在損傷檢測(cè)中已有許多應(yīng)用,然而其固有的色散和多模態(tài)等特征使得接收信號(hào)的解讀面臨挑戰(zhàn)。相比于Lamb波,SH波在頻率低于一階截止頻率時(shí),具有模態(tài)單一且無(wú)色散的優(yōu)點(diǎn)。因此,SH波在無(wú)損檢測(cè)中極具研究?jī)r(jià)值和應(yīng)用前景。根據(jù)Navier運(yùn)動(dòng)方程,采用勢(shì)函數(shù)法,聯(lián)系邊界條件求解板中導(dǎo)波的色散方程。根據(jù)超聲導(dǎo)波的傳播理論,并參照超聲導(dǎo)波的探傷流程,分析SH波在損傷檢測(cè)領(lǐng)域的特點(diǎn)和優(yōu)勢(shì)。基于壓電雙向耦合效應(yīng)及本構(gòu)方程,研究了壓電材料的導(dǎo)波激發(fā)理論和特征,建立三維有限元數(shù)值模型模擬研究了d_(36)型壓電晶片在金屬板中所激發(fā)的導(dǎo)波場(chǎng)。提取和分析面內(nèi)的位移場(chǎng)信息,對(duì)比傳統(tǒng)的d35型壓電材料,證明了d_(36)型壓電材料在金屬板中高效激發(fā)/傳感SH波的能力。討論了d_(36)型壓電晶片在金屬板中激發(fā)各模態(tài)導(dǎo)波的空間分布狀況,為金屬板中SH波的高效激發(fā)提供理論基礎(chǔ)。基于d_(36)型壓電晶片激發(fā)的SH波,建立SH波與兩種不同類型損傷相互作用的有限元數(shù)值模型。針對(duì)金屬板中的裂縫損傷,利用波形的變化評(píng)價(jià)SH波檢測(cè)裂縫損傷的能力;針對(duì)金屬板中的腐蝕損傷,以反射系數(shù)評(píng)估SH波對(duì)板中腐蝕損傷的敏感程度。本文基于數(shù)值模擬,探究了d_(36)型壓電材料的激發(fā)特征,給出了高效激發(fā)SH波的方法;討論了SH波與金屬板中兩類損傷的相互作用,為SH波探測(cè)特定類型損傷提供了理論依據(jù)。
[Abstract]:Ultrasonic guided waves have the advantages of long propagation distance and low energy loss, which have become the focus of research in the field of structural health monitoring and nondestructive testing. There are Lamb waves and Shear Horizontal: SH waves in thin plate structures. Lamb waves have many applications in damage detection, but their inherent dispersion and multi-mode characteristics make the interpretation of received signals difficult. Compared with Lamb wave SH wave, it has the advantages of single mode and no dispersion when the frequency is lower than the first-order cutoff frequency. Therefore, SH-wave is of great value and application prospect in nondestructive testing. According to the Navier equation of motion, the dispersion equation of guided waves in the plate is solved by using the potential function method and the boundary conditions. According to the theory of ultrasonic guided wave propagation and referring to the flaw detection flow of ultrasonic guided wave, the characteristics and advantages of SH wave in the field of damage detection are analyzed. Based on the piezoelectric bidirectional coupling effect and constitutive equation, the guided wave excitation theory and characteristics of piezoelectric materials are studied. A three-dimensional finite element numerical model is established to simulate the guided wave field excited by d _ (36) piezoelectric wafer in a metal plate. The displacement field information in plane is extracted and analyzed. Compared with the traditional d35 type piezoelectric material, the ability of d _ (36) type piezoelectric material to excite / sense SH wave efficiently in metal plate is proved. The spatial distribution of guided waves excited by d36 type piezoelectric wafers in metal plates is discussed, which provides a theoretical basis for the efficient excitation of SH waves in metal plates. Based on the SH waves excited by d36 piezoelectric wafers, a finite element numerical model for the interaction of SH waves with two different types of damage is established. Aiming at crack damage in metal plate, the ability of detecting crack damage by SH wave is evaluated by waveform change, and the sensitivity of SH wave to corrosion damage in plate is evaluated by reflection coefficient for corrosion damage in metal plate. Based on numerical simulation, the excitation characteristics of d _ (36) type piezoelectric materials are investigated, the method of highly efficient excitation of SH waves is given, and the interaction between SH waves and two kinds of damage in metal plates is discussed, which provides a theoretical basis for SH waves to detect specific types of damage.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG115.285

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本文編號(hào)：2059503