本文選題：虛擬激勵(lì) + 結(jié)構(gòu)振動(dòng)　； 參考：《南京航空航天大學(xué)》2017年碩士論文

【摘要】：航空航天以及土木等工程結(jié)構(gòu)由于自然災(zāi)害或疲勞、腐蝕等會(huì)產(chǎn)生不同程度的損傷,經(jīng)過長(zhǎng)期的累積必然會(huì)導(dǎo)致結(jié)構(gòu)破壞或使用性能降低。為了提高結(jié)構(gòu)的安全性與可靠性,無(wú)損檢測(cè)技術(shù)得到了越來(lái)越多的關(guān)注�！疤摂M激勵(lì)”法作為一種基于振動(dòng)與非接觸式激光測(cè)量技術(shù)的損傷檢測(cè)方法近年來(lái)逐漸得到發(fā)展,其在檢測(cè)過程中無(wú)需整體結(jié)構(gòu)的振動(dòng)模型或基準(zhǔn)信號(hào)。本文基于“虛擬激勵(lì)”法進(jìn)行了以下幾個(gè)方面的研究。首先,深入研究了傳統(tǒng)的“虛擬激勵(lì)”法。針對(duì)傳統(tǒng)方法需要借助嚴(yán)格的振動(dòng)微分方程以及依賴結(jié)構(gòu)的力學(xué)參數(shù)的缺點(diǎn),在各類板梁理論的基礎(chǔ)上,本文提出了一種基于廣義振動(dòng)模型識(shí)別的損傷檢測(cè)方法(General Vibration Model Identification,GVMI)。該方法以多階微分方程形式描述結(jié)構(gòu)的振動(dòng)響應(yīng),利用最小二乘法擬合方程中的系數(shù),從而建立了結(jié)構(gòu)的廣義局部振動(dòng)微分方程。接著,以鋁蜂窩夾層懸臂梁為例建立有限元模型,考慮損傷位于蒙皮和芯層兩種情況,定量評(píng)估單頻點(diǎn)力激勵(lì)下GVMI方法的損傷檢測(cè)效果,選取合適的采樣間距,提高了其抗噪能力。改變損傷位置,針對(duì)出現(xiàn)的檢測(cè)盲區(qū),探討兩種情況下?lián)p傷與位移波長(zhǎng)間的關(guān)系,分析了兩者不敏感區(qū)域差異的原因。在此基礎(chǔ)上,通過擴(kuò)展激勵(lì)頻率對(duì)GVMI方法進(jìn)行了優(yōu)化,確定有效頻率范圍,將損傷指數(shù)進(jìn)行歸一化并對(duì)數(shù)據(jù)進(jìn)行了融合,消除了檢測(cè)盲區(qū)。最后,搭建了實(shí)驗(yàn)平臺(tái),利用掃描式激光測(cè)振儀采集試件各點(diǎn)的振動(dòng)位移,對(duì)單個(gè)與多個(gè)損傷分別進(jìn)行定位,驗(yàn)證了兩種損傷方式下GVMI方法的可行性。
[Abstract]:Due to natural disasters or fatigue, corrosion of engineering structures such as aerospace and civil engineering will lead to varying degrees of damage, and long-term accumulation will inevitably lead to structural damage or performance degradation. In order to improve the safety and reliability of structures, nondestructive testing (NDT) technology has been paid more and more attention. As a damage detection method based on vibration and non-contact laser measurement technique, the "virtual excitation" method has been developed gradually in recent years. In the detection process, there is no need for the vibration model or reference signal of the whole structure. In this paper, the following aspects are studied based on the "virtual excitation" method. Firstly, the traditional "virtual excitation" method is deeply studied. In view of the disadvantages of traditional methods which need to rely on strict differential equations of vibration and mechanical parameters of structures, a damage detection method based on generalized vibration model identification is proposed in this paper, which is based on the theory of plate and beam. In this method, the vibration response of the structure is described in the form of multi-order differential equation, and the coefficients in the equation are fitted by the least square method, and then the generalized local vibration differential equation of the structure is established. Then, taking the aluminum honeycomb sandwich cantilever beam as an example, the finite element model is established. Considering the damage located in the skin and core layer, the damage detection effect of GVMI method under single frequency point force excitation is quantitatively evaluated, and the appropriate sampling spacing is selected. The anti-noise ability is improved. The relationship between the damage and the displacement wavelength is discussed in the light of the blind spot of the detection. The reason of the difference between the two insensitive areas is analyzed. On this basis, the GVMI method is optimized by expanding the excitation frequency, the effective frequency range is determined, the damage index is normalized and the data is fused to eliminate the blind area of detection. Finally, an experimental platform is set up. The vibration displacement of each point of the specimen is collected by scanning laser vibration measuring instrument, and the single or multiple damage is located separately, which verifies the feasibility of the GVMI method under two kinds of damage modes.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB523

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