本文選題：ABAQUS + CT試驗　； 參考：《長安大學》2017年碩士論文

【摘要】：混凝土材料在動荷載作用下,會導致其的力學性能發(fā)生很大的變化,其破壞過程是一個非常復雜的非線性材料損傷過程。本文利用細觀力學、隨機數(shù)學方法和數(shù)值計算理論相結合,來分析混凝土試件在沖擊荷載作用的變形、損傷和破壞過程。利用有限元軟件ABAQUS對混凝土試件在不同加載速率和不同加載幅值下受到?jīng)_擊荷載作用下的單軸受壓和單軸拉伸破壞的數(shù)值模擬,研究不同加載速率以及加載幅值對混凝土強度的影響。利用CT技術能夠觀察混凝土材料中裂紋的萌生、發(fā)展以及最終貫通破壞過程,通過對比數(shù)值計算結果與CT試驗結果,總結混凝土材料的破壞機理和破壞形態(tài)。本文通過數(shù)值模擬和CT試驗分析,研究成果如下:(1)在不同加載速率下的沖擊荷載條件下,對混凝土試件的單軸受壓模擬時,速率越大,其強度也會增大。當速率提高2.5倍時,試件的平均強度提高了2%;當加載速率提高4倍時,試件的平均強度提高了7.3%。對混凝土試件的單軸拉伸模擬時,當速率提高2.5倍時,試件的平均強度提高了53%;當加載速率提高4倍時,試件的平均強度提高了57%。(2)在不同加載幅值下的沖擊荷載條件下,對混凝土試件的單軸受壓模擬時,我們發(fā)現(xiàn),混凝土的強度隨著加載幅值的增大而增大。當加載幅值提高2倍時,平均強度提高了2.6%。當加載幅值提高3倍時,試件的平均強度提高了5.6%。(3)對于在不同加載速率以及不同加載幅值條件下的單軸受壓模擬,我們得知,混凝土的破壞最開始是從界面層發(fā)生的,即界面層的強度最低。產(chǎn)生的裂紋隨著外荷載的增大向砂漿層發(fā)展,最后直至裂紋貫穿整個混凝土試件。破壞形式為呈45度的剪切破壞。對于不同加載速率下的單軸拉伸模擬時,我們通過分析數(shù)值計算結果發(fā)現(xiàn),其破壞是在混凝土試件底部形成一條貫穿橫截面的宏觀裂紋。(4)通過對比混凝土試件在沖擊荷載作用下的單軸受壓和單軸拉伸數(shù)值模擬損傷云圖與CT試驗獲得的CT圖像,我們總結,兩種方式下混凝土破壞裂紋的發(fā)展及破壞形態(tài)與CT試驗結果比較相近,驗證了本文對混凝土進行單軸受壓和單軸拉伸數(shù)值模擬的可行性。
[Abstract]:Under dynamic load, the mechanical properties of concrete material will change greatly, and the damage process of concrete material is a very complicated nonlinear material damage process. In this paper, the deformation, damage and failure process of concrete specimens under impact load are analyzed by means of the combination of meso-mechanics, stochastic mathematical method and numerical calculation theory. The finite element software ABAQUS is used to simulate the uniaxial compression and uniaxial tensile failure of concrete specimens under different loading rates and different loading amplitudes. The effects of different loading rates and loading amplitude on the strength of concrete are studied. The crack initiation, development and ultimate penetrating failure process in concrete can be observed by using CT technique. The failure mechanism and failure pattern of concrete material are summarized by comparing the numerical results with the results of CT test. Through numerical simulation and CT test analysis, the research results are as follows: 1) under different loading rates, the strength of concrete specimen under uniaxial compression will increase with the increase of the rate. The average strength of the specimen was increased by 2. 5 times when the loading rate was increased by 2. 5 times, and by 7. 3% when the loading rate was 4 times higher. In uniaxial tensile simulation of concrete specimens, the average strength of concrete specimens increases by 53 when the rate increases by 2.5 times, and when the loading rate increases by 4 times, the average strength of specimens increases by 57% under different loading amplitudes. Under uniaxial compression simulation of concrete specimens, it is found that the strength of concrete increases with the increase of loading amplitude. When the loading amplitude is increased by 2 times, the average strength is increased by 2.6 times. When the loading amplitude is increased by three times, the average strength of the specimen is increased by 5.60.The uniaxial compression simulation under different loading rates and different loading amplitudes shows that the failure of concrete begins from the interface layer. That is, the interfacial layer has the lowest strength. The resulting crack develops to the mortar layer with the increase of the external load, and finally the crack runs through the whole concrete specimen. The failure form is 45 degrees shear failure. For uniaxial tensile simulation at different loading rates, we find that, The failure is to form a macroscopic crack at the bottom of the concrete specimen. (4) by comparing the uniaxial compression and uniaxial tension of the concrete specimen under impact load, the damage cloud diagram and the CT image obtained by the CT test are simulated. We conclude that the development and failure pattern of concrete failure crack in two ways are close to the results of CT test, which verifies the feasibility of uniaxial compression and uniaxial tensile numerical simulation of concrete in this paper.
【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU528

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本文編號：1935403