發(fā)布時(shí)間：2018-05-05 06:22

  本文選題：Lamb波 + 結(jié)構(gòu)健康監(jiān)測(cè)��； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：在過(guò)去的二十年間,結(jié)構(gòu)健康監(jiān)測(cè)技術(shù)(SHM)因其在薄板結(jié)構(gòu)中優(yōu)于傳統(tǒng)的無(wú)損檢測(cè)技術(shù),而獲得了學(xué)術(shù)界的廣泛關(guān)注。在不同研究方法中,基于Lamb波的方法有很多優(yōu)點(diǎn)而被廣泛應(yīng)用。壓電陶瓷傳感器被用來(lái)在薄板結(jié)構(gòu)中激勵(lì)和探測(cè)Lamb波,通過(guò)激勵(lì)和探測(cè)經(jīng)結(jié)構(gòu)不同部位反射回的Lamb波,我們可以判斷損傷的位置和程度。復(fù)合材料層合板被大量應(yīng)用于航空航天領(lǐng)域,但在其服役過(guò)程中常經(jīng)受沖擊載荷。所以,針對(duì)復(fù)合材料層合板沖擊損傷的結(jié)構(gòu)損傷識(shí)別研究是十分有意義的。本文的主要研究?jī)?nèi)容包括:首先對(duì)Lamb波的基本特性進(jìn)行了詳細(xì)的闡述,從構(gòu)建各向同性體中彈性波的運(yùn)動(dòng)方程入手,代入板的邊界條件,得到了各向同性材料板中Lamb波的頻散方程,以及相速度與群速度的關(guān)系,以鋁板和鋼板為例繪制了頻散曲線。推導(dǎo)了截止頻率的表達(dá)形式,指出了其應(yīng)用意義。根據(jù)分波理論,推導(dǎo)了各向異性材料層中,Lamb波的頻散方程。這些工作為后面的研究打下了基礎(chǔ),提供了理論依據(jù)。接著詳細(xì)地介紹了Lamb波在復(fù)合材料層合板中傳播行為有限元模擬的相關(guān)內(nèi)容。首先介紹了顯式動(dòng)態(tài)算法,接著對(duì)傳感器和損傷的模型建立分別進(jìn)行了說(shuō)明和相關(guān)理論闡述,然后給出了有限元仿真的具體過(guò)程以及相關(guān)參數(shù)設(shè)置的解釋,最后簡(jiǎn)單分析了有限元仿真結(jié)果�？偟膩�(lái)說(shuō),完整的提供了一套關(guān)于含沖擊損傷復(fù)合材料層合板中Lamb波傳播行為有限元仿真的方法。最后針對(duì)第三章有限元仿真所得結(jié)果,進(jìn)行了簡(jiǎn)單的信號(hào)處理及損傷位置識(shí)別。利用典型頻域法快速傅里葉變換及時(shí)頻法小波變換進(jìn)行了信號(hào)處理,比較了不同頻率下Lamb波的傳播特性,定性地判斷了損傷的存在性,并且對(duì)比了時(shí)頻法與頻域法的優(yōu)缺點(diǎn)。之后基于Lamb波信號(hào)的飛行時(shí)間,利用橢圓定位法對(duì)損傷位置進(jìn)行了粗略的識(shí)別,考慮到算法中的近似,誤差范圍可以接受。同時(shí)也側(cè)面地證明了前面所用建模仿真方法的正確性和有效性。
[Abstract]:In the past 20 years, structural health monitoring (SHM) technology has attracted much attention because it is superior to traditional nondestructive testing (NDT) technology in thin plate structures. In different research methods, the method based on Lamb wave has many advantages and is widely used. Piezoelectric ceramic sensors are used to excite and detect Lamb waves in thin plate structures. By exciting and detecting Lamb waves reflected from different parts of the structure, we can judge the location and extent of damage. Composite laminates are widely used in aerospace field, but they are often subjected to impact load during their service. Therefore, it is of great significance to study the structural damage identification of composite laminated plates. The main contents of this paper are as follows: firstly, the basic characteristics of Lamb waves are described in detail, and the boundary conditions of plates are replaced by constructing the equations of motion of elastic waves in isotropic bodies. The dispersion equation of Lamb wave in isotropic plate and the relationship between phase velocity and group velocity are obtained. The dispersion curves of aluminum plate and steel plate are plotted. The expression of cutoff frequency is derived and its application significance is pointed out. The dispersion equation of Lamb wave in anisotropic material layer is derived according to the theory of fractional wave. These work have laid the foundation for the later research and provided the theoretical basis. Then the finite element simulation of Lamb wave propagation in composite laminates is introduced in detail. Firstly, the explicit dynamic algorithm is introduced, then the modeling of sensor and damage is explained and related theories are explained, then the concrete process of finite element simulation and the explanation of relevant parameter setting are given. Finally, the finite element simulation results are simply analyzed. In general, a complete finite element simulation method of Lamb wave propagation in composite laminates with impact damage is provided. Finally, a simple signal processing and damage location identification are carried out according to the results of finite element simulation in chapter 3. In this paper, the fast Fourier transform (FFT) method in frequency domain is used to process the signal, the propagation characteristics of Lamb waves at different frequencies are compared, the existence of damage is judged qualitatively, and the advantages and disadvantages of time-frequency method and frequency-domain method are compared. Then, based on the time of flight of Lamb wave signal, the damage location is roughly identified by elliptical localization method. Considering the approximation in the algorithm, the error range is acceptable. At the same time, the correctness and validity of the previous modeling and simulation methods are also proved.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB33

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本文編號(hào)：1846600