發(fā)布時(shí)間：2018-07-06 09:42

  本文選題：Lamb波 + 復(fù)合材料��； 參考：《重慶大學(xué)》2015年碩士論文

【摘要】：隨著工業(yè)技術(shù)的快速發(fā)展,對(duì)工程應(yīng)用中的材料屬性要求越來(lái)越高。復(fù)合材料以高強(qiáng)度、大彈性模量、輕質(zhì)量等方面優(yōu)勢(shì)在工業(yè)界得到廣泛使用。復(fù)合材料結(jié)構(gòu)的健康與否直接關(guān)系到系統(tǒng)的完整性和安全性,在復(fù)合材料層合板中最常見(jiàn)缺陷類型有纖維斷裂、基體裂紋、脫層等,其中最難以檢測(cè)的是內(nèi)部脫層缺陷,這種缺陷嚴(yán)重影響復(fù)合材料的屬性,在使用中存在著極大的安全隱患,國(guó)內(nèi)外曾多次出現(xiàn)因脫層缺陷導(dǎo)致重大事故,所以復(fù)合材料中的脫層檢測(cè)至關(guān)重要。本文使用Lamb波對(duì)脫層缺陷進(jìn)行檢測(cè)研究,分析Lamb波在復(fù)合材料板中傳播原理并進(jìn)行有限元模擬仿真,運(yùn)用時(shí)間反轉(zhuǎn)方法、小波分析法達(dá)到無(wú)基準(zhǔn)檢測(cè)目的,并根據(jù)概率成像原理實(shí)現(xiàn)復(fù)合材料板的脫層缺陷二維平面成像。本文首先研究Lamb波在復(fù)合材料板中傳播理論方程以及Lamb波的檢測(cè)原理,求得頻散方程,繪制頻散曲線;對(duì)時(shí)間反轉(zhuǎn)方法做了詳細(xì)理論分析,并利用時(shí)間反轉(zhuǎn)法和小波分析法建立無(wú)基準(zhǔn)脫層檢測(cè)基礎(chǔ);通過(guò)對(duì)時(shí)反后聚焦信號(hào)的分析和與原始激勵(lì)信號(hào)的比對(duì),提出時(shí)反聚焦性能評(píng)價(jià)指標(biāo)和小波差異系數(shù)評(píng)估指標(biāo),并以此作為下文中脫層區(qū)域成像的重要參數(shù)。在理論研究的基礎(chǔ)上,利用有限元分析軟件建立Lamb波在復(fù)合材料板中傳播模型,以一維Lamb波線傳播模型和二維Lamb波平面?zhèn)鞑ツＰ头抡鎸?duì)復(fù)合材料板導(dǎo)波傳播特性進(jìn)行深入研究。通過(guò)對(duì)檢測(cè)信號(hào)的處理分析,確定是否存在脫層缺陷、定位脫層以及分析脫層尺寸對(duì)信號(hào)的影響,針對(duì)難處理的檢測(cè)波形,提出“中心波峰去除法”,這一方法解決了信號(hào)微弱和缺陷反射回波與直達(dá)波混疊的問(wèn)題,大大提高信號(hào)分析的有效性和準(zhǔn)確性。利用時(shí)間反轉(zhuǎn)法的重構(gòu)性和小波差異系數(shù)實(shí)現(xiàn)層合板的二維概率脫層損傷成像,成功實(shí)現(xiàn)單處多層和多處脫層的成像顯示,并對(duì)成像結(jié)果進(jìn)行正確修正,能非常精確的定位到預(yù)設(shè)脫層損傷位置。
[Abstract]:With the rapid development of industrial technology, the requirements for material properties in engineering applications are becoming higher and higher. Composite materials are widely used in industrial circles with the advantages of high strength, large elastic modulus and light quality. The health of composite materials is directly related to the integrity and safety of the system, and is the most common in composite laminates. Defect types include fiber fracture, matrix crack, delamination and so on. The most difficult to detect is the internal delamination defect. This defect seriously affects the properties of composite materials. There is a great potential for safety in use. The delamination defects have occurred many times at home and abroad, so the delamination detection in the composite is very important. The Lamb wave is used to detect the delamination defect, and the propagation principle of Lamb wave in the composite plate is analyzed and the finite element simulation is carried out. The time reversal method and wavelet analysis are used to achieve the goal of non reference detection, and the two-dimensional plane imaging of the delamination defect of the composite plate is realized according to the principle of probability imaging. This paper first studies the Lamb wave. In the composite plate, the theoretical equation and the detection principle of Lamb wave are propagated, the dispersion equation is obtained and the frequency dispersion curve is drawn. The time reversal method is analyzed in detail, and the time reversal method and the wavelet analysis method are used to establish the basis of the non datum delamination detection, and the analysis of the time reversal focusing signal and the ratio of the original excitation signal to the original excitation signal. On the basis of the theoretical research, the propagation model of Lamb wave in the composite plate is established on the basis of the theoretical research, and the one dimension Lamb wave line propagation model and the two-dimensional Lamb wave plane propagation model are established. The simulation of the propagation characteristics of composite material plate guided wave. Through the analysis of the detection signal processing, determine whether there are delamination defects, location delamination and analysis of the influence of delamination size on the signal. In view of the difficult processing waveform, the "center wave peak removal method" is proposed. This method solves the weak and defect reflection of the signal. The problem of echo and direct wave aliasing greatly improves the effectiveness and accuracy of the signal analysis. Using the reconfiguration of the time reversal method and the wavelet difference coefficient, the two-dimensional delamination damage imaging of the laminate is realized, and the imaging display of the single layer and multiple delamination is successfully realized, and the correct correction of the imaging results can be made in a very accurate manner. Position to presupposition delamination damage.
【學(xué)位授予單位】：重慶大學(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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