【摘要】：全場(chǎng)位移／應(yīng)變測(cè)量對(duì)實(shí)驗(yàn)力學(xué)非常重要,數(shù)字體積相關(guān)方法是真正三維全場(chǎng)變形測(cè)量的工具之一。本論文針對(duì)數(shù)字體積相關(guān)方法的開發(fā)、拓展和應(yīng)用展開研究。1)利用牛頓爬山法、最小二乘法、三次B樣條插值,自行開發(fā)一套數(shù)字體積相關(guān)算法。利用兩組泡沫金屬樣品的CT數(shù)據(jù),對(duì)算法進(jìn)行了系統(tǒng)評(píng)測(cè),發(fā)現(xiàn)所開發(fā)的數(shù)字體積相關(guān)算法有較好的表現(xiàn)。在沒有噪音的理想情況下,數(shù)字體積相關(guān)算法的位移誤差為0.0065 voxel;在有X-CT噪音的情況下,位移誤差增加到0.008 voxel,應(yīng)變誤差增加到100με。通過模擬剛性平動(dòng)測(cè)試分析數(shù)字體積相關(guān)方法的誤差特點(diǎn),發(fā)現(xiàn)誤差主要來源于噪音和插值運(yùn)算,其中插值主要影響其正確度,噪音主要影響其精確度。2)在已開發(fā)的數(shù)字體積相關(guān)算法基礎(chǔ)上,提出了基于圖像配準(zhǔn)和基于位移梯度加性分解的兩套異位數(shù)字體積相關(guān)方法。通過模擬平動(dòng)、轉(zhuǎn)動(dòng)、平動(dòng)轉(zhuǎn)動(dòng)耦合和單軸壓縮變形實(shí)驗(yàn)對(duì)兩種方法進(jìn)行了評(píng)價(jià)。在小變形和小轉(zhuǎn)動(dòng)條件下,這兩種方法有著和原位數(shù)字體積相關(guān)方法相似的精確度。兩種方法各有優(yōu)點(diǎn),基于圖像配準(zhǔn)的異位數(shù)字體積方法可以計(jì)算大變形,基于位移梯度加性分解的異位數(shù)字體積相關(guān)方法更容易操作。兩種方法相互補(bǔ)充,擴(kuò)展了數(shù)字體積相關(guān)方法的應(yīng)用范圍。3)泡沫金屬的出色性能使其具有重要的應(yīng)用價(jià)值和研究意義。本研究通過異位數(shù)字體積相關(guān)方法定量表征開孔泡沫鋁在四個(gè)不同壓縮狀態(tài)下的內(nèi)部位移場(chǎng)和應(yīng)變場(chǎng),獲得其在元胞級(jí)變形的演變規(guī)律。研究發(fā)現(xiàn)：位移場(chǎng)觀察到的壓縮變形是均勻的,但在應(yīng)變場(chǎng)卻觀察到局部應(yīng)變帶的產(chǎn)生；應(yīng)變值的空間分布和頻率分布都顯示了泡沫鋁變形的異質(zhì)性,而且該異質(zhì)性與局部孔隙率沒有相關(guān)性；在元胞尺度上,壓縮、轉(zhuǎn)動(dòng)和剪切是同時(shí)增加的,這表明了泡沫鋁變形模式的復(fù)雜性；由元胞變形導(dǎo)致的附近元胞轉(zhuǎn)動(dòng)是減輕應(yīng)變集中的主要變形模式。
[Abstract]:Full-field displacement/strain measurement is very important to experimental mechanics. Digital volume correlation method is one of the real three-dimensional deformation measurement tools. This paper focuses on the development, development and application of digital volume correlation method. Pass algorithm. Using the CT data of two sets of foam metal samples, the algorithm is systematically evaluated. It is found that the developed digital volume correlation algorithm has a good performance. In the absence of noise, the displacement error of digital volume correlation algorithm is 0.0065 voxel, and the displacement error increases to 0.008 voxel with the presence of X-CT noise. Variable error is increased to 10096 And two sets of ectopic digital volume correlation methods based on displacement gradient additive decomposition are evaluated by simulating translation, rotation, translation-rotation coupling and uniaxial compression deformation experiments. There are advantages. The ectopic digital volume method based on image registration can calculate large deformation. The ectopic digital volume correlation method based on displacement gradient additive decomposition is easier to operate. The two methods complement each other and extend the application scope of the digital volume correlation method..3) the excellent performance of foam metal has important application value and research. In this study, the internal displacement and strain fields of open cell aluminum foam in four different compression states were quantitatively characterized by ectopic digital volume correlation method. The evolution rule of deformation at cellular level was obtained. It was found that the compressive deformation observed in the displacement field was homogeneous, but the local strain band was observed in the strain field. The spatial distribution and frequency distribution of strain values show the heterogeneity of the deformation of aluminum foam, and the heterogeneity is not related to the local porosity. At the cell scale, compression, rotation and shear increase simultaneously, indicating the complexity of the deformation mode of the aluminum foam, and the rotation of the nearby cell caused by cell deformation is mitigated. The main deformation modes of variable concentration.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.4

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