本文關(guān)鍵詞：基于微觀結(jié)構(gòu)的顆粒增強(qiáng)復(fù)合材料力學(xué)性能數(shù)值分析　出處：《上海交通大學(xué)》2015年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 顆粒增強(qiáng)金屬基復(fù)合材料 3D有限元模型 應(yīng)變梯度 界面強(qiáng)度 粘聚力模型

【摘要】：顆粒增強(qiáng)金屬基復(fù)合材料具有高強(qiáng)度、高彈性模量、耐磨損和導(dǎo)電導(dǎo)熱性能好等特點(diǎn),廣泛應(yīng)用于航空航天、電子、汽車及建筑等行業(yè)。由于顆粒增強(qiáng)金屬基復(fù)合材料最大的缺點(diǎn)是其延伸率和斷裂韌性較低,目前先進(jìn)復(fù)合材料設(shè)計(jì)研究致力于揭示微觀組織對(duì)復(fù)合材料變形和破壞機(jī)制的影響規(guī)律。但是微觀結(jié)構(gòu)如顆粒形貌、大小、分布、含量及界面性能對(duì)復(fù)合材料整體性能影響至今還沒有得到充分的了解。關(guān)于微觀結(jié)構(gòu)對(duì)復(fù)合材料力學(xué)性能的影響數(shù)值研究,以前三維(Three-dimensional,3D)多顆粒有限元模型分別分析了顆粒形貌、分布及界面損傷的單一或共同作用,但是都沒有考慮基體中應(yīng)變梯度的作用,不能考察微米尺度下復(fù)合材料中顆粒大小變化對(duì)整體性能的影響。針對(duì)上述問題,本文建立了顆粒增強(qiáng)復(fù)合材料3D周期性有限元分析模型,采用擴(kuò)展應(yīng)變梯度理論研究顆粒大小對(duì)基體中應(yīng)變梯度強(qiáng)化影響;采用粘聚力模型模擬界面損傷對(duì)復(fù)合材料的弱化作用。首先推導(dǎo)了擴(kuò)展應(yīng)變梯度理論在有限元中的應(yīng)力、應(yīng)變?cè)隽扛鹿?而后采用基于節(jié)點(diǎn)平均塑性應(yīng)變計(jì)算塑性應(yīng)變梯度的方法,開發(fā)編寫了有限元軟件Abaqus的用戶子程序UMAT和URDFIL,將擴(kuò)展應(yīng)變梯度理論嵌入有限元中進(jìn)行計(jì)算。通過和實(shí)驗(yàn)結(jié)果的對(duì)比證明了本文模型的正確性。然后本文建立了顆粒大小、形貌、界面強(qiáng)度及分布各不相同的有限元模型,以SiC顆粒增強(qiáng)Al基體復(fù)合材料為例,分析了微觀結(jié)構(gòu)變化對(duì)復(fù)合材料單軸拉伸彈塑性力學(xué)行為、顆粒/基體載荷分配、局部應(yīng)力應(yīng)變場(chǎng)分布、界面損傷起始和發(fā)展的影響規(guī)律。并且分析了顆粒大小、形貌對(duì)復(fù)合材料中熱殘余應(yīng)力大小及分布以及熱殘余應(yīng)力對(duì)材料在后續(xù)加載過程中的力學(xué)性能的影響。本文的數(shù)值分析表明:(1)在顆粒形貌和大小相同的情況下,界面越強(qiáng),復(fù)合材料的流動(dòng)應(yīng)力、拉伸強(qiáng)度、均勻應(yīng)變?cè)礁�。在界面�?qiáng)度和顆粒形貌相同的情況下,顆粒越小復(fù)合材料的流動(dòng)應(yīng)力、拉伸強(qiáng)度和均勻應(yīng)變?cè)礁�。在界面�?qiáng)度和顆粒大小相同的情況下,顆粒形貌對(duì)均勻應(yīng)變影響比較一致,都是球形顆粒材料的均勻應(yīng)變較高。顆粒形貌對(duì)流動(dòng)應(yīng)力的影響受界面強(qiáng)度的影響:在弱界面的條件下,兩類材料的流動(dòng)應(yīng)力基本一致;但在強(qiáng)界面條件下,立方顆粒材料中的流動(dòng)應(yīng)力高于球形顆粒材料。綜合來講,強(qiáng)界面條件下立方小顆粒增強(qiáng)材料的流動(dòng)應(yīng)力最高,強(qiáng)度最好;而強(qiáng)界面條件下球形小顆粒材料均勻應(yīng)變最大,韌性最好。(2)對(duì)3D單個(gè)顆粒和多個(gè)顆粒隨機(jī)分布的模型對(duì)比分析表明:對(duì)于球形顆粒增強(qiáng)材料,單個(gè)顆粒模型和多個(gè)顆粒模型計(jì)算得到的流動(dòng)應(yīng)力曲線和均勻應(yīng)變的差異幾乎可以忽略,因此可以用單個(gè)顆粒模型分析復(fù)合材料的性能以節(jié)省計(jì)算資源。對(duì)于立方顆粒增強(qiáng)材料,單個(gè)顆粒模型計(jì)算得到的流動(dòng)應(yīng)力低于多個(gè)顆粒模型的流動(dòng)應(yīng)力,主要由于單個(gè)顆粒模型假設(shè)所有顆粒界面損傷同步發(fā)生,在加載早期會(huì)高估界面中的平均損傷,導(dǎo)致顆粒中的平均應(yīng)力水平從加載早期就明顯低于多顆粒模型中的值。因此應(yīng)采用多顆粒模型對(duì)立方顆粒增強(qiáng)復(fù)合材料性能進(jìn)行評(píng)估。(3)其它情況相同時(shí),顆粒團(tuán)聚分布、層狀分布和隨機(jī)分布下的流動(dòng)應(yīng)力基本一致。但是顆粒分布狀態(tài)對(duì)均勻應(yīng)變的影響較大。當(dāng)顆粒層狀分布時(shí),材料的均勻應(yīng)變?cè)谒蟹植贾凶钚?主要是由于拉伸方向垂直于層面,界面損傷容易快速發(fā)展。與一般的實(shí)驗(yàn)結(jié)果不同,顆粒的團(tuán)聚分布并沒有對(duì)材料性能造成損傷,材料的均勻應(yīng)變反而高于顆粒均勻分布時(shí)候的值。這主要是由于本文的模型沒有考慮顆粒團(tuán)聚分布可能帶來的缺陷,如團(tuán)簇內(nèi)部的空隙的影響。本章的計(jì)算結(jié)果表明,相對(duì)于其他顆粒分布狀態(tài),顆粒團(tuán)聚現(xiàn)象本身不會(huì)對(duì)復(fù)合材料性能造成損傷。(4)當(dāng)復(fù)合材料從高溫冷卻到室溫時(shí),平均熱殘余應(yīng)力(絕對(duì)值)的大小隨顆粒尺寸的增加而增加;立方顆粒材料中的熱殘余應(yīng)力明顯高于球形顆粒材料中的值。熱殘余應(yīng)力(應(yīng)變)對(duì)復(fù)合材料彈性模量和微屈服行為影響比較大,對(duì)流動(dòng)應(yīng)力有微弱的影響。整體來講,熱殘余應(yīng)力使得材料微屈服強(qiáng)度降低,流動(dòng)應(yīng)力稍微增加,熱殘余塑性應(yīng)變使得材料彈性模量下降。熱殘余應(yīng)力對(duì)復(fù)合材料中的界面損傷影響很小,有或者沒有熱殘余應(yīng)力的復(fù)合材料的均勻應(yīng)變非常接近。以上這些結(jié)論,對(duì)復(fù)合材料的優(yōu)化設(shè)計(jì)具有重要的理論依據(jù)的意義。
[Abstract]:Particle reinforced metal matrix composite material with high strength, high elastic modulus, wear-resistant characteristics and good thermal conductivity properties, widely used in aerospace, electronics, automobile and construction industries. Because of particle reinforced metal matrix composites, the biggest drawback is its elongation and fracture toughness is low, the current research of advanced composite materials the design aims to reveal the microstructure of the composite deformation and failure mechanism of the influence law. But the microstructure such as particle morphology, size, distribution, content and interface properties of the overall performance of the composite materials still have not been fully understood. The influence of microstructure on the mechanical properties of the composites were investigated, the previous 3D (Three-dimensional 3D), the finite element model of multi particles were analyzed by particle morphology, distribution and function of single or joint interface damage, but did not consider the strain matrix Gradient, change the size of particles in the composite can not be investigated at micron scale on the overall performance. Aiming at the above problems, this paper established the particle reinforced composites 3D periodic finite element analysis model, using extended strain gradient theory of particle size on the matrix strain gradient strengthening effect; the cohesion model simulation interface weakening effect the composite material damage. Firstly, extension strain gradient theory in finite element stress, strain increment update formula, then the node average plastic strain calculation method of plastic strain gradient based on the developed finite element software Abaqus user subroutine UMAT and URDFIL, will be extended to calculate the strain gradient theory embedded finite element. By comparing with the experimental results to demonstrate the correctness of this model. Then this paper established the particle size, morphology, interface The intensity and distribution of different finite element model with SiC particle reinforced Al matrix composite materials as an example, analyzed the microstructure change of composite uniaxial tensile elastic-plastic behavior of load distribution of the particle / matrix, local stress and strain field distribution, interface damage initiation and development. The influence and analysis the particle size and morphology of the composite material thermal residual should influence the size and distribution of residual stress and thermal stress on the mechanical properties of materials in the subsequent loading process. The numerical analysis shows that: (1) in the same shape and particle size under the condition that the interface is strong, flow stress of composites the tensile strength, strain, even higher. The morphology of interfacial strength and particle under the same, the smaller the particle flow stress of composites, the tensile strength and uniform strain is high. In the interface strength and particle size under the same circumstances, a Effect of particle morphology on uniform strain is consistent, is even higher strain spherical particles. The influence of particle shape on the flow stress is affected by the interfacial strength in weak interface under the condition of two kinds of material flow stress are basically the same; but in strong interface conditions, cube in granular material flow the stress is higher than that of spherical particles. In general, the material flow stress intensity is highest, the best under the condition of strong interface cubic particles reinforced; small spherical particles and strong interface under the condition of uniform material strain is the largest, best toughness. (2) the model comparison between 3D particles and a plurality of single particle random distribution analysis showed that: for the spherical particle reinforced material, calculated by single particle model and multiple model particle flow difference of stress curve and uniform strain is almost negligible, so you can analyze properties of composite materials with single particle model To save computational resources. The cubic particle reinforced material, calculated by single particle model of flow stress is lower than a particle model of flow stress, mainly because of the single particle model assumes that all particles interface damage occur simultaneously, in the early stage of loading will overestimate the average damage in the interface, resulting in an average particle stress level from loading early is obviously lower than that of the values of the model. So the particles should adopt multi particle model of cubic particle reinforced composites to evaluate the performance. (3) other conditions are the same, the particle agglomeration distribution, layered distribution and random distribution of the flow stress are basically the same. But the effect of particle distribution on the uniform strain greatly. When when the particle layer distribution, the minimum in all materials uniform strain distribution, mainly due to the tensile direction perpendicular to the interface level, easy to damage with a like rapid development. The experimental results of different particle distribution and agglomeration caused no damage to the material properties, uniform strain material is higher than that of the particle distribution time value. This is mainly because this model does not consider the particle agglomeration distribution may be caused by defects, such as air gap clusters. The effect of this chapter the calculation results show that, compared with the other particle distribution, particle agglomeration itself does not cause damage to the properties of the composite materials. (4) when the composite cooling from high temperature to room temperature, the average thermal residual stress (absolute value) of the size increase with the increase of the particle size; thermal residual stress in the cubic granular material was significantly higher than that of spherical particles in the material the value of thermal residual stress (strain) is relatively large on the elastic modulus of composites and micro yield behavior influence on flow stress have little effect. Overall, the thermal residual stress of the material micro The yield strength is reduced, the flow stress increases slightly, the thermal residual plastic strain makes the elastic modulus decreased. The thermal residual stress is very small on the influence of interfacial damage in composite materials, with or without the thermal residual stress of the composite uniform strain is very close. These conclusions have important theoretical basis for the optimization design composite meaning.

【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB33

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本文編號(hào)：1386327