复合材料层合板结构非局部渐进失效建模与有限元分析

发布时间：2018-06-25 13:16

本文选题：碳纤维复合材料层合板 + 渐进失效分析方法　；参考：《浙江大学》2015年硕士论文

【摘要】：碳纤维增强复合材料由碳纤维增强体和树脂基体组成,它具有一系列优异性能,如高强度、可设计性强、低密度、低热膨胀系数等,是先进材料领域重点开发、研究的一种结构材料,具有良好的应用前景。然而,复合材料失效机理通常非常复杂,对强度、刚度、损伤容限以及剩余寿命的评估和预测提出了较大挑战。目前,国内外在复合材料渐进失效领域已经开展了诸多研究,然而通常实际应用中的复合材料几何形状和失效机理复杂,经常导致应力集中和局部化问题,根本特征是刚度退化带来的应变软化问题,这使得运用常规有限元分析结构力学性能失去客观性,数值求解失去意义。这是因为局部化问题自然引入了尺度比例而连续介质力学缺乏尺度比例参数。目前国内外在复合材料局部化问题的研究非常少。本文基于非局部积分理论和连续损伤力学理论,针对碳纤维复合材料层合板结构,基于ABAQUS有限元软件发展了有限元数值计算技术,开展了非局部渐进失效分析,深入研究了含中心开孔复合材料层合板的渐进失效机理和强度。取得的研究进展如下：(1)建立了复合材料层合板渐进失效分析预测理论模型,确定了以等效应变作为判断纤维和基体失效的参量,推导了针对纤维断裂和基体开裂损伤变量的破坏进化律及一致切线模量,为复合材料的强度预测提供理论支撑。(2)基于非局部积分理论,将控制应变软化的内变量-等效应变进行非局部平均处理,从而在模型中引入针对纤维和基体的两个尺度比例参数,最后针对隐式有限元求解问题,推导了各向异性非局部一致切线模量,为解决复合材料应变局部化问题提供了理论基础。(3)运用ABAQUS-UEL(用户自定义单元子程序模块),UMAT(用户自定义材料子程序模块),USDFLD(用户场变量子程序模块)和UEXTERNALDB(用户外部数据接口应用子程序模块),开展数值编程,实现了提出的非局部渐进失效模型,从而形成了复合材料非局部渐进失效分析数值计算技术。(4)针对含中心圆孔复合材料层合板结构,运用上述提出的非局部渐进失效理论模型,开展了非局部有限元分析,与试验结果进行比较,探讨了开孔半径、铺层方式、网格尺寸和非局部尺度比例参数对复合材料层合板渐进失效特性和强度、刚度的影响规律。
[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.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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