本文選題：CFRP　切入點(diǎn)：孔隙率　出處：《大連理工大學(xué)》2015年碩士論文

【摘要】：碳纖維增強(qiáng)復(fù)合材料(Carbon Fibre Reinforced Plastics, CFRP)孔隙率超聲檢測(cè)是無(wú)損檢測(cè)領(lǐng)域的研究熱點(diǎn)之一,其中超聲衰減法應(yīng)用最為廣泛,該方法的理論模型主要包括規(guī)則孔隙模型和隨機(jī)孔隙模型(Random Void Model, RVM),前者假設(shè)孔隙為規(guī)則幾何形狀、服從固定分布函數(shù),與實(shí)際孔隙形貌差異較大,理論結(jié)果與實(shí)驗(yàn)結(jié)果存在較大偏差；后者將孔隙復(fù)雜、隨機(jī)形貌考慮在內(nèi),理論結(jié)果與實(shí)驗(yàn)結(jié)果的偏差明顯降低,但基于數(shù)學(xué)方法構(gòu)建出來(lái)的孔隙與實(shí)際孔隙形貌仍然存在差異,且當(dāng)樣品中孔隙尺寸離散程度大時(shí)建模效果不理想。為了更加真實(shí)、準(zhǔn)確地描述CFRP孔隙形貌,本文提出通過(guò)建立真實(shí)形貌孔隙模型(Real Morphology Void Model, RMVM)來(lái)研究CFRP孔隙率、孔隙形貌與超聲衰減系數(shù)之間的復(fù)雜關(guān)系。研究對(duì)象為16層預(yù)浸料制備的單向CFRP層壓板,采用連續(xù)切片法獲得441張CFRP金相照片,通過(guò)中值濾波、二值化等圖像處理方法對(duì)真實(shí)孔隙形貌特征進(jìn)行原位提取,建立孔隙率范圍在0.58%-3.49%之間的RMVM。采用時(shí)域有限差分法對(duì)RMVM進(jìn)行數(shù)值模擬計(jì)算,得到衰減系數(shù)α孔隙率P變化的統(tǒng)計(jì)結(jié)果。研究表明,α隨P增加而增加,二者呈α=0.905+1.053P+0.039P2的二次曲線關(guān)系；相同孔隙率下不同RMVM的衰減系數(shù)在一定范圍內(nèi)分布,即α與P呈帶狀分布關(guān)系,且孔隙率越高帶寬越大。通過(guò)實(shí)驗(yàn)測(cè)量得到的衰減系數(shù)基本分布在模擬數(shù)據(jù)帶內(nèi),說(shuō)明基于RMVM的模擬計(jì)算具有可行性。此外,根據(jù)模擬結(jié)果初步探究了孔隙數(shù)量、面積、寬度、高度等形貌參量對(duì)衰減系數(shù)的影響。本文建立的RMVM可以真實(shí)地描述CFRP中孔隙形貌的復(fù)雜性和隨機(jī)性,為澄清孔隙導(dǎo)致的超聲波散射衰減機(jī)理提供了很好的模型基礎(chǔ)。
[Abstract]:Ultrasonic testing of carbon Fibre Reinforced plastics (CFRP) porosity is one of the hot topics in the field of nondestructive testing, in which ultrasonic attenuation method is the most widely used.The theoretical models of this method mainly include regular pore model and random Void model. The former assumes that the pore is a regular geometric shape, and follows a fixed distribution function, which is different from the actual pore morphology.There is a big deviation between the theoretical results and the experimental results, the latter takes the pore complexity and random morphology into account, and the deviation between the theoretical results and the experimental results is obviously reduced.However, there are still differences between the pore morphology and the actual pore morphology based on mathematical method, and the modeling effect is not ideal when the pore size dispersion degree in the sample is large.In order to describe CFRP pore morphology more realistically and accurately, this paper proposes to study the complex relationship between CFRP porosity, pore morphology and ultrasonic attenuation coefficient by establishing a real morphology pore model, Real Morphology Void Model (RMVM).One-way CFRP laminates prepared from 16 layers of prepreg were studied. 441 CFRP metallographic photographs were obtained by serial slice method. The real pore morphology was extracted in situ by median filter and binarization image processing methods.To establish RMVM with porosity ranging from 0.58% to 3.49%.The finite difference time-domain (FDTD) method is used to simulate the RMVM, and the statistical results of the attenuation coefficient 偽 -porosity P are obtained.The results show that 偽 increases with the increase of P, and they are conic of 偽 0.9051.053P 0.039P2, and the attenuation coefficients of different RMVM are distributed in a certain range under the same porosity, that is, 偽 and P show a zonal distribution relationship, and the higher the porosity, the larger the bandwidth.The attenuation coefficient obtained by the experimental measurement is basically distributed in the simulated data band, which shows that the simulation calculation based on RMVM is feasible.In addition, based on the simulation results, the effects of the number of pores, area, width and height on the attenuation coefficient are preliminarily investigated.The RMVM established in this paper can describe the complexity and randomness of pore morphology in CFRP and provide a good model basis for clarifying the attenuation mechanism of ultrasonic scattering induced by pores.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TB33;TB302.5

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本文編號(hào)：1729850