本文選題：超高韌性水泥基復(fù)合材料 + 擴(kuò)展有限元　； 參考：《山東科技大學(xué)》2017年碩士論文

【摘要】：混凝土是實(shí)際生產(chǎn)中不可或缺的建筑材料,隨著生產(chǎn)的需要,高性能混凝土發(fā)揮越來(lái)越重要的作用。其中,超高韌性水泥基復(fù)合材料(UHTCC)的研究也引起人們的重視。超高韌性水泥基復(fù)合材料通過(guò)優(yōu)化基體、纖維、纖維與基體界面的基本性能以及三者之間的相互作用,使得該材料在纖維摻量很少的情況下,具有多縫開(kāi)裂和應(yīng)變硬化的特點(diǎn)。近幾十年來(lái),國(guó)內(nèi)外學(xué)者對(duì)UHTCC在靜力和動(dòng)載方面對(duì)裂縫開(kāi)展和斷裂韌度方面做了很全面和詳細(xì)的試驗(yàn)研究,但是對(duì)UHTCC斷裂方面的仿真研究尚少,目前使用主要方法是擴(kuò)展有限元(XFEM)法。擴(kuò)展有限元(XFEM)是在常規(guī)有限元框架上求解不連續(xù)問(wèn)題的有效數(shù)值模擬方法。其網(wǎng)格劃分、材料尺寸與表面物理狀態(tài)無(wú)關(guān),對(duì)解決裂紋尖端高應(yīng)力區(qū)和變形區(qū)的網(wǎng)格加密復(fù)雜問(wèn)題有著無(wú)可比擬的優(yōu)勢(shì),在動(dòng)態(tài)裂紋擴(kuò)展的歷程中也不需要隨裂紋擴(kuò)展更新網(wǎng)格。本文結(jié)合單軸拉伸試驗(yàn)研究結(jié)果并利用軟件模擬優(yōu)勢(shì),對(duì)UHTCC的裂紋擴(kuò)展進(jìn)行仿真分析并與試驗(yàn)結(jié)果對(duì)比,主要研究?jī)?nèi)容包括了以下幾個(gè)方面。1) UHTCC單軸直接拉伸試驗(yàn)研究通過(guò)采用尺寸為305 mm× 76 mm× 13 mm的試件進(jìn)行纖維摻量和普通水泥基的單軸直接拉伸試驗(yàn),研究材料的應(yīng)變硬化現(xiàn)象和纖維摻量對(duì)基體的增韌效果,并計(jì)算UHTCC試件的斷裂能。(1)使用一定摻量的纖維混凝土比普通混凝土有較好的韌性,隨著纖維摻量的不同,出現(xiàn)不同程度的應(yīng)變硬化現(xiàn)象。當(dāng)纖維摻量為2%,應(yīng)變硬化現(xiàn)象最為明顯,受力比較均勻。當(dāng)摻加一定量纖維時(shí),混凝土的破壞不再是脆性破壞,并在主裂縫周?chē)霈F(xiàn)許多微細(xì)裂縫。(2)由試驗(yàn)得出的應(yīng)力-裂縫寬度曲線(xiàn),根據(jù)曲線(xiàn)包圍的面積,以2%纖維摻量試件(5AF-2)為例,計(jì)算出其斷裂能為11190N/m。2)三點(diǎn)彎曲梁靜載試驗(yàn)研究了 PVA纖維的摻入、尺寸效應(yīng)、縫高比等因素對(duì)試件的斷裂性能影響和裂縫擴(kuò)展的現(xiàn)象,利用雙K斷裂準(zhǔn)則,分析其起裂荷載、峰值荷載、起裂韌度和失穩(wěn)斷裂韌度。(1)對(duì)于纖維水泥基體試件,同一尺寸,同一配合比試件,初始縫高比越大,起裂荷載和峰值荷載越小,起裂韌度幾乎不隨縫高比的增大發(fā)生變化,失穩(wěn)斷裂韌度在一定程度上有所降低。對(duì)于無(wú)纖維摻量水泥基隨著初始縫高比的增加,其起裂韌度和失穩(wěn)斷裂韌度增幅并不明顯,呈現(xiàn)一定的離散性。(2)同一配合比,同一縫高的纖維混凝土基體,當(dāng)試件尺寸變大時(shí),相應(yīng)的起裂韌度和失穩(wěn)斷裂韌度也會(huì)明顯增加。3)利用XFEM方法模擬研究UHTCC三點(diǎn)彎曲梁的不同縫高比的裂紋擴(kuò)展規(guī)律和斷裂性能,并將模擬結(jié)果與試驗(yàn)結(jié)果對(duì)比分析,驗(yàn)證利用XFEM模擬UHTCC斷裂問(wèn)題的可行性,得到以下結(jié)論:(1)通過(guò)后處理的應(yīng)力云紋圖,在裂縫未起裂前,在預(yù)制縫的尖端部分有較明顯的應(yīng)力集中現(xiàn)象,當(dāng)裂縫擴(kuò)展時(shí)應(yīng)力集中現(xiàn)象消失,并且隨著縫高比的增加,應(yīng)力集中現(xiàn)象更加明顯。(2)在一定的縫高比范圍內(nèi),同一尺寸的UHTCC試件梁,隨著縫高比的增加,起裂韌度影響較小,失穩(wěn)斷裂韌度逐漸變小,試驗(yàn)測(cè)出的起裂荷載、峰值荷載與模擬計(jì)算得出相差不大,根據(jù)起裂荷載、峰值荷載計(jì)算出的起裂韌度和失穩(wěn)斷裂韌度離散性較小。因此,利用ABAQUS中的擴(kuò)展有限元(XFEM)分析UHTCC的斷裂性能具有一定的可行性。
[Abstract]:Concrete is an indispensable building material in actual production. With the need of production, high performance concrete plays a more and more important role. Among them, the research of ultra high toughness cementitious composites (UHTCC) has also aroused people's attention. The ultra high toughness cementitious composites have passed the basic interface of the matrix, fiber, fiber and matrix. The interaction between the three and the three makes the material characterized by multiple crack cracking and strain hardening in the case of little fiber content. In recent decades, domestic and foreign scholars have done a comprehensive and detailed study on the fracture development and fracture toughness of the cracks in static and dynamic loads, but for the fracture of UHTCC. The main method is the extended finite element (XFEM) method. The extended finite element (XFEM) is an effective numerical simulation method to solve the discontinuous problem on the conventional finite element framework. The grid division, the material size and the surface physical state are independent, and the complex problem of the grid encryption in the high stress zone and the deformation zone at the tip of the breaking point is solved. With unparalleled advantage, there is no need to extend the mesh with the crack propagation in the process of dynamic crack propagation. This paper combines the results of the uniaxial tensile test and uses the advantages of the software simulation to simulate the crack propagation of UHTCC and compare it with the experimental results. The main research contents include the following aspects: the single axis of the.1) UHTCC The direct tensile test of direct tensile test by using a specimen with a size of 305 mm x 76 mm x 13 mm to carry out the uniaxial direct tensile test of fiber content and ordinary cementitious test, studies the strain hardening of the material and the toughening effect of the fiber content to the matrix, and calculates the fracture energy of the UHTCC specimen. (1) the fiber concrete is mixed with a certain amount of fiber. There is a good toughness in the soil. With the different fiber content, strain hardening occurs at different degrees. When the fiber content is 2%, the strain hardening is most obvious and the stress is more uniform. When adding a certain amount of fiber, the damage of concrete is no longer brittle failure, and there are many fine cracks around the main crack. (2) the test results are obtained. The stress crack width curve, according to the area surrounded by the curve, is taken as an example of the 2% fiber content test specimen (5AF-2). The fracture energy is 11190N/m.2) and the three point bending Liang Jing load test is used to study the effect of PVA fiber incorporation, the size effect, the crack height ratio and other factors on the fracture performance and crack expansion of the specimen, and the analysis of the double K fracture criterion is used. The cracking load, the peak load, the crack toughness and the instability fracture toughness. (1) for the fiber cement matrix, the same size, the same size, the higher the initial joint height ratio, the smaller the cracking load and the peak load, the crack toughness almost does not change with the increase of the seam height ratio, and the instability fracture toughness decreases to a certain extent. With the increase of the initial crack height ratio, the increase of the crack toughness and the instability fracture toughness is not obvious, and a certain discreteness is presented. (2) the same mix ratio, the same joint height of the fiber concrete matrix, when the specimen size becomes larger, the corresponding crack toughness and the instability fracture toughness will also increase obviously.3) using the XFEM method model. It is proposed to study the crack propagation law and fracture performance of UHTCC three point bending beam with different slots and height ratios. The simulation results are compared with the test results to verify the feasibility of using XFEM to simulate the UHTCC fracture problem. The following conclusions are obtained: (1) the stress moire chart of the post treatment is more obvious in the tip of the prefabricated seam before the crack is not cracked. The stress concentration phenomenon is disappearing when the crack expands, and the stress concentration phenomenon is more obvious with the increase of the seam height ratio. (2) in the range of certain seam height ratio, the UHTCC specimen beam of the same size, with the increase of the seam height ratio, the effect of the crack toughness is smaller, the instability fracture toughness gradually becomes smaller and the test crack load is measured. The difference between the peak load and the simulated calculation is small. According to the cracking load, the fracture toughness and the instability fracture toughness calculated by the peak load are smaller. Therefore, it is feasible to use the extended finite element (XFEM) in the ABAQUS to analyze the fracture properties of UHTCC.
【學(xué)位授予單位】：山東科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TU528

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 劉金祥;張華陽(yáng);李軍;;基于擴(kuò)展有限元法的Ⅰ-Ⅱ復(fù)合型裂紋擴(kuò)展研究[J];北京理工大學(xué)學(xué)報(bào);2015年09期

2 胡少偉;米正祥;;鋼筋混凝土三點(diǎn)彎曲梁裂縫擴(kuò)展過(guò)程模擬[J];水利水運(yùn)工程學(xué)報(bào);2015年03期

3 束一秀;李亞智;姜薇;賈雨軒;;基于擴(kuò)展有限元的多裂紋擴(kuò)展分析[J];西北工業(yè)大學(xué)學(xué)報(bào);2015年02期

4 高淑玲;史宏飛;王海超;;基于擴(kuò)展有限元法的應(yīng)變硬化材料ECC的斷裂破壞仿真分析[J];應(yīng)用基礎(chǔ)與工程科學(xué)學(xué)報(bào);2015年02期

5 林騁;王金昌;;基于ABAQUS的擴(kuò)展有限元尺寸效應(yīng)研究[J];華東公路;2014年06期

6 胡少偉;魯文妍;;基于XFEM的混凝土三點(diǎn)彎曲梁開(kāi)裂數(shù)值模擬研究[J];華北水利水電大學(xué)學(xué)報(bào)(自然科學(xué)版);2014年04期

7 李麗丹;磨季云;;基于擴(kuò)展有限元的Ⅰ-Ⅱ復(fù)合型裂紋開(kāi)裂角分析[J];武漢科技大學(xué)學(xué)報(bào);2014年02期

8 王海超;秦敬平;赫慶坤;高淑玲;張玲玲;王志軍;;基于“名義斷裂能”的概念研究超高性能水泥基復(fù)合材料的斷裂特性[J];混凝土;2013年09期

9 劉問(wèn);徐世p，

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