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  本文選題：碳纖維復合材料層合板 + 漸進失效分析方法��； 參考：《浙江大學》2015年碩士論文

【摘要】：碳纖維增強復合材料由碳纖維增強體和樹脂基體組成,它具有一系列優(yōu)異性能,如高強度、可設(shè)計性強、低密度、低熱膨脹系數(shù)等,是先進材料領(lǐng)域重點開發(fā)、研究的一種結(jié)構(gòu)材料,具有良好的應用前景。然而,復合材料失效機理通常非常復雜,對強度、剛度、損傷容限以及剩余壽命的評估和預測提出了較大挑戰(zhàn)。目前,國內(nèi)外在復合材料漸進失效領(lǐng)域已經(jīng)開展了諸多研究,然而通常實際應用中的復合材料幾何形狀和失效機理復雜,經(jīng)常導致應力集中和局部化問題,根本特征是剛度退化帶來的應變軟化問題,這使得運用常規(guī)有限元分析結(jié)構(gòu)力學性能失去客觀性,數(shù)值求解失去意義。這是因為局部化問題自然引入了尺度比例而連續(xù)介質(zhì)力學缺乏尺度比例參數(shù)。目前國內(nèi)外在復合材料局部化問題的研究非常少。本文基于非局部積分理論和連續(xù)損傷力學理論,針對碳纖維復合材料層合板結(jié)構(gòu),基于ABAQUS有限元軟件發(fā)展了有限元數(shù)值計算技術(shù),開展了非局部漸進失效分析,深入研究了含中心開孔復合材料層合板的漸進失效機理和強度。取得的研究進展如下：(1)建立了復合材料層合板漸進失效分析預測理論模型,確定了以等效應變作為判斷纖維和基體失效的參量,推導了針對纖維斷裂和基體開裂損傷變量的破壞進化律及一致切線模量,為復合材料的強度預測提供理論支撐。(2)基于非局部積分理論,將控制應變軟化的內(nèi)變量-等效應變進行非局部平均處理,從而在模型中引入針對纖維和基體的兩個尺度比例參數(shù),最后針對隱式有限元求解問題,推導了各向異性非局部一致切線模量,為解決復合材料應變局部化問題提供了理論基礎(chǔ)。(3)運用ABAQUS-UEL(用戶自定義單元子程序模塊),UMAT(用戶自定義材料子程序模塊),USDFLD(用戶場變量子程序模塊)和UEXTERNALDB(用戶外部數(shù)據(jù)接口應用子程序模塊),開展數(shù)值編程,實現(xiàn)了提出的非局部漸進失效模型,從而形成了復合材料非局部漸進失效分析數(shù)值計算技術(shù)。(4)針對含中心圓孔復合材料層合板結(jié)構(gòu),運用上述提出的非局部漸進失效理論模型,開展了非局部有限元分析,與試驗結(jié)果進行比較,探討了開孔半徑、鋪層方式、網(wǎng)格尺寸和非局部尺度比例參數(shù)對復合材料層合板漸進失效特性和強度、剛度的影響規(guī)律。
[Abstract]:Carbon fiber reinforced composites are composed of carbon fiber reinforcements and resin matrix. It has a series of excellent properties, such as high strength, high designability, low density, low thermal expansion coefficient and so on. A kind of structural material studied in this paper has a good prospect of application. However, the failure mechanism of composite materials is usually very complex, which poses a great challenge to the evaluation and prediction of strength, stiffness, damage tolerance and residual life. At present, many researches have been carried out in the field of progressive failure of composite materials at home and abroad. However, the geometric shape and failure mechanism of composite materials in practical applications are often complicated, which often lead to the problem of stress concentration and localization. The fundamental characteristic is the strain softening problem caused by stiffness degradation, which makes the use of conventional finite element analysis of the mechanical properties of the structure lose objectivity, and the numerical solution is meaningless. This is because the localization problem naturally introduces the scale and the continuum mechanics lacks the scale parameter. At present, there are few researches on localization of composite materials at home and abroad. Based on the nonlocal integral theory and the theory of continuous damage mechanics, the finite element numerical calculation technology is developed based on Abaqus finite element software for carbon fiber composite laminated plate structure, and the nonlocal progressive failure analysis is carried out. The progressive failure mechanism and strength of composite laminates with central holes were studied. The research progress is as follows: (1) A theoretical model of progressive failure analysis and prediction of composite laminates is established, and the equivalent strain is used as the parameter to judge the failure of fiber and matrix. The damage evolution law and uniform tangent modulus for fiber fracture and matrix cracking damage variables are derived, which provide theoretical support for the strength prediction of composites. (2) based on the nonlocal integral theory, The internal variable, equivalent strain, which controls strain softening, is treated with non-local average, and two scale proportional parameters for fiber and matrix are introduced into the model. Finally, the implicit finite element method is used to solve the problem. The anisotropic nonlocal uniform tangent modulus is derived. It provides a theoretical basis for solving the strain localization problem of composite materials. (3) using AbaquUS-UEL (user-defined unit subroutine module) UMAT (user-defined material subroutine module) USDFLD (user field variable subroutine module) and UEXTERNALDB (user external data) Interface application subroutine module), carry out numerical programming, The proposed nonlocal progressive failure model is realized, and the numerical calculation technique for nonlocal progressive failure analysis of composite materials is formed. (4) for the composite laminated plate structure with a central circular hole, the above proposed nonlocal progressive failure theory model is used. The non-local finite element analysis was carried out and compared with the experimental results. The effects of the opening radius, layering mode, mesh size and non-local scale ratio parameters on the progressive failure characteristics, strength and stiffness of composite laminates were discussed.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB33

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相關(guān)期刊論文 前2條

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本文編號：2066070