【摘要】：三維編織復(fù)合材料既是一種材料又是一種結(jié)構(gòu),通過(guò)特殊的編織工藝可以直接編織成各種復(fù)雜形狀,避免二次加工,使其在具有高比強(qiáng)度和比高剛度的同時(shí)不存在易分層等一系列問(wèn)題,在航空航天和民用領(lǐng)域具有很大的應(yīng)用潛力。因此,能夠快速和準(zhǔn)確地對(duì)三維編織復(fù)合材料的力學(xué)性能進(jìn)行分析與評(píng)估顯得愈發(fā)重要。三維編織復(fù)合材料的細(xì)觀結(jié)構(gòu)特征決定了它的宏觀力學(xué)性能,建立一個(gè)能夠精確反映其細(xì)觀結(jié)構(gòu)的模型至關(guān)重要。本文從細(xì)觀角度出發(fā),結(jié)合圖像處理和斷層掃描技術(shù)(Micro-CT),構(gòu)造三維編織復(fù)合材料的細(xì)觀幾何模型,進(jìn)而對(duì)材料的力學(xué)性能進(jìn)行分析。首先,介紹了一種基于Micro-CT的三維編織復(fù)合材料精細(xì)化幾何模型重建方法。利用Micro-CT對(duì)三維四向編織復(fù)合材料進(jìn)行逐層斷層掃描,采用濾波、膨脹和收縮等方法處理掃描切片圖像,編寫了程序自動(dòng)識(shí)別切片圖像內(nèi)所有纖維束的截面輪廓,通過(guò)對(duì)纖維束截面圖進(jìn)行輪廓提取、離散、插值、截面重建等操作,把纖維束截面圖轉(zhuǎn)化為拓?fù)鋽?shù)據(jù),建立了與材料真實(shí)細(xì)觀結(jié)構(gòu)相一致的精細(xì)化模型。該精細(xì)化建模方法具有通用性,可用于其他三維編織復(fù)合材料的幾何建模。其次,在三維編織復(fù)合材料精細(xì)化幾何拓?fù)浣Y(jié)構(gòu)基礎(chǔ)之上,采用一種非均勻Voxel網(wǎng)格對(duì)材料的模型進(jìn)行有限元離散,并對(duì)材料的宏觀有效性能進(jìn)行計(jì)算分析。纖維束內(nèi)部Voxel網(wǎng)格單元尺寸呈梯度變化,在精細(xì)刻畫材料內(nèi)部相界面處的幾何特征的同時(shí)降低了模型的計(jì)算規(guī)模。從精細(xì)化模型中提取一個(gè)代表性單胞模型和一個(gè)小尺寸模型,采用體積平均化方法計(jì)算材料工程常數(shù),并且與理想橢圓截面的代表性單胞模型結(jié)果進(jìn)行對(duì)比分析。針對(duì)纖維束打捻現(xiàn)象,研究了纖維束扭曲對(duì)材料宏觀力學(xué)性能的影響。最后,采用剛度折減模型對(duì)三維編織復(fù)合材料在單軸拉伸載荷作用下的累積損傷過(guò)程進(jìn)行模擬分析。采用應(yīng)力平均化技術(shù)去除Voxel網(wǎng)格在不同相界面引入的應(yīng)力集中,再利用平均化的應(yīng)力判斷組分材料是否發(fā)生損傷,然后考察三種計(jì)算模型(從精細(xì)化模型中提取的代表性單胞模型、從精細(xì)化模型中隨機(jī)提取的小尺寸模型和橢圓截面的理想代表性單胞模型)、纖維束不同扭曲程度以及Voxel網(wǎng)格尺寸對(duì)計(jì)算結(jié)果的影響。
[Abstract]:Three-dimensional braided composites are both a kind of material and a kind of structure. Through special braiding technology, they can be woven into various complex shapes directly, avoiding secondary processing. Because of its high specific strength and high stiffness, it does not have a series of problems such as easy stratification and so on, so it has great application potential in aerospace and civil fields. Therefore, it is more important to analyze and evaluate the mechanical properties of 3D braided composites quickly and accurately. The macroscopic mechanical properties of 3D braided composites are determined by their microstructural characteristics. It is very important to establish a model that can accurately reflect the microstructure of braided composites. In this paper, a mesoscopic geometric model of 3D braided composites is constructed by combining image processing and Micro-CT, and the mechanical properties of the composites are analyzed. Firstly, a method of 3D braided composite fine geometric model reconstruction based on Micro-CT is introduced. Three-dimensional four-direction braided composite material was scanned layer by Micro-CT. The scanning slice image was processed by filtering, expanding and shrinking methods, and the program was written to automatically recognize the cross-section contour of all fiber bundles in the slice image. By means of contour extraction, discrete, interpolation, section reconstruction and so on, the fiber bundle section is transformed into topological data, and a fine model consistent with the real meso-structure of the material is established. The refined modeling method is universal and can be used in geometric modeling of other 3D braided composites. Secondly, based on the refined geometric topology of 3D braided composite, a non-uniform Voxel mesh is used to discretize the material model by finite element method, and the macroscopic effective performance of the material is calculated and analyzed. The size of the Voxel mesh cells in the fiber bundle varies in gradient, which reduces the computational scale of the model while accurately characterizing the geometric characteristics of the interface of the internal phase of the material. A representative cell model and a small size model were extracted from the refined model, and the material engineering constants were calculated by volume averaging method, and the results were compared with the results of the representative cell model with ideal elliptical section. According to the twisting phenomenon of fiber bundle, the effect of fiber bundle twist on the macroscopic mechanical properties of the material was studied. Finally, the cumulative damage process of three dimensional braided composites under uniaxial tensile loading is simulated by using stiffness reduction model. Stress averaging technique is used to remove the stress concentration introduced by Voxel mesh at different phase interfaces, and then the average stress is used to judge whether the component material is damaged or not. Then three kinds of computational models (the representative unit cell model extracted from the refined model) were investigated. Small size model and ideal representative cell model of elliptical section are extracted from the refined model. The effects of different twisting degree of fiber bundle and Voxel mesh size on the calculation results are discussed.
【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】：2017
【分類號(hào)】：TB332

【參考文獻(xiàn)】

相關(guān)期刊論文 前6條

1 鞏龍東;申秀麗;;基于能量法的三維四向編織復(fù)合材料細(xì)觀建模[J];航空動(dòng)力學(xué)報(bào);2015年01期

2 汪星明;邢譽(yù)峰;;三維編織復(fù)合材料研究進(jìn)展[J];航空學(xué)報(bào);2010年05期

3 田金梅;邢譽(yù)峰;;一種新的三維四步編織復(fù)合材料幾何模型及其在宏觀彈性性能預(yù)測(cè)中的應(yīng)用[J];航空學(xué)報(bào);2007年01期

4 龐寶君,杜善義,韓杰才,王鐸;三維多向編織復(fù)合材料非線性本構(gòu)行為的細(xì)觀數(shù)值模擬[J];復(fù)合材料學(xué)報(bào);2000年01期

5 龐寶君,杜善義,韓杰才;三維四向編織復(fù)合材料細(xì)觀組織及分析模型[J];復(fù)合材料學(xué)報(bào);1999年03期

6 吳德隆,郝兆平;五向編織結(jié)構(gòu)復(fù)合材料的分析模型[J];宇航學(xué)報(bào);1993年03期

相關(guān)博士學(xué)位論文 前1條

1 方國(guó)東;三維四向碳/環(huán)氧編織復(fù)合材料積累損傷及失效分析[D];哈爾濱工業(yè)大學(xué);2010年

，

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