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三维机织正交结构复合材料抗冲击性能及其有限元分析

The Impact Resistance and Finite Element Analysis of Three-dimensional Orthogonal Woven Composites

作者: 专业:纺织工程 导师:祝成炎 年度:2010 学位:硕士  院校: 浙江理工大学

Keywords

3D orthogonal woven, Composites, Quasi-static impact, Parametric model, Finite element analysis, Pro/Engineer, ANSYS/LS-DYNA

        基于模型参数化设计与有限元理论,通过对三维正交机织复合材料纤维增强体的细观结构分析,本文利用CAD软件Pro/Engineer建立了三维机织正交结构复合材料的单胞模型的程序,该程序可以通过设定织造参数生成相应的模型。建立的模型可以导入有限元软件ANSYS/ LS-DYNA中,并对复合材料的准静态冲击过程进行了模拟计算。将模拟的结果与准静态实验进行对比表明,有限元方法模拟计算值与实验值总体变化趋势一致,且误差较小,验证了该有限元模拟方法的正确性和可行性,并探讨了复合材料受到冲击载荷时的内部应力变化趋势,为三维机织结构复合材料的性能研究、结构设计和工程应用等提供了一定的理论基础。通过本论文工作可获得如下主要结论:(1)利用万能试验机对复合材料进行准静态冲击实验,得到载荷位移曲线、能量吸收曲线和破坏模式。通过分析可知复合材料冲击破坏分为几个阶段,其中在冲击开始到复合材料出现初始穿透的阶段,复合材料受到的破坏对其力学性能影响较大。复合材料的破坏模式除了基体受到破坏和纤维增强体受到抽拔、拉伸之外,还包括在剪切方向的破坏,复合材料受到冲击后其正面主要受到压缩破坏,而背面的拉伸破坏比较严重。(2)通过显式求解器LS-DYNA对三维机织复合材料准静态冲击过程的模型进行计算,得到有限元法模拟准静态冲击过程的结果。该结果与实验室条件下的载荷位移曲线、材料的能量吸收曲线和破坏模式进行对比校验,表明有限元方法模拟值与实验值总体变化趋势一致,且预测值与实验值的误差较小,验证了该有限元模型的准确性和可行性。(3)从细观结构层面对复合材料受到冲击后的破坏进行分析,能够清晰确切的查看材料的具体破坏过程和材料在冲击过程中所受的应力变化。通过对纤维增强体与基体随时间变化的应力云图分析,可以看到,复合材料受到的应力随着冲击的进行逐渐增大,在受到冲头冲击的“十”字型区域受到的应力最大,所受到的破坏也最大,与准静态冲击实验中板材发生破坏的最大区域相符。(4)通过分析三维机织复合材料不同层面的单元受到的应力随时间的变化曲线,得出复合材料在受到冲击时,与冲头接触部分的单元发生破坏是由于该单元的有效应变达到失效应变设定值,与冲头没有接触到的单元发生破坏是由于该单元达到材料的最大屈服应力。冲头与纤维增强体的接触力大于冲头与基体之间的接触力,纤维增强体与基体之间的接触力较小,说明在冲击过程中两者之间接触紧密,界面滑移现象不明显
    On the base of parametric design theory and the finite element theory, a general single-cell model program of three-dimensional orthogonal woven composites is established in this paper with the CAD software Pro/Engineer by the analysis to the micro-fiber-reinforced of the three-dimensional orthogonal woven composite. The program can generate a corresponding model by setting the woven parameters, which can import into the finite element software ANSYS/LS-DYNA and simulate the quasi-static impact process. Comparing the results of the finite element analysis (FEA) with the measured ones, it shows that the two follow the same trend, and they have small error, which means that the FEA method is available for prediction of 3D orthogonal woven composites. What is more, in this paper, the trend of internal stress of the composite subject to impact load is discussed; some basic theories are provided for the three-dimensional woven composites’design and engineering applications. The main conclusions of this paper are as follows.(1) Universal testing machine was used in the quasi-static impact experiments, from which the load-displacement curves, energy absorption curves and failure modes were obtained. Through the analysis of the curves, it shows that the impact damage can be divided into several stages. It is in the beginning of the impact that the greater effect was found to the mechanical properties of composite materials. Besides the matrix was destroyed and fiber reinforcement was pulled-out, the composites’failure modes had the shear deformation during the impact. The composite took the compression failure on the front side and the tensile failure on the back side.(2) By computing the finite element model of the process of quasi-static impact with the explicit expression solver LS-DYNA, we got the results of the finite element model of the process of quasi-static impact. Compared with the load displacement curve, the material energy absorption curve and the failure mode we got from experiments, it showed that they had the same trend and the error was smaller, which mean that the FEA method is available for prediction of 3D orthogonal woven composites.(3) To analyze the destructive of the composite of the impact in micro-level, and it is clear and precise to see the concrete process of the destruction and the stress suffered at any time. Through the analysis of the fiber-reinforced body and the matrix with the stress changing over time, we can get that the stress of the composites increases following the impact, and the crisscross pattern area impacted by the punch got the utmost stress as well as the worst destruction, which is similar to laboratory experiments.(4) By analyzing the dynamic curves of the element at different levels of the cell, we can know that, the elements touching with the punch get failure because the elements’effective strain got the set value; the elements not touching with the punch get failure because they realize the biggest yield stress. The contact force between the punch and the fiber reinforcement is bigger than that between the punch and the matrix. The contract force between fiber reinforcement and matrix is small, it shows that they close contract with each other, and the boundary sliding is not distinct.
        

三维机织正交结构复合材料抗冲击性能及其有限元分析

摘要4-6
ABSTRACT6-7
第一章 绪论10-17
    1.1 引言10-11
    1.2 三维机织复合材料细观结构研究现状11-13
    1.3 纺织复合材料准静态冲击力学性能研究现状13-14
    1.4 有限元分析现状14-15
    1.5 目前存在的问题15
    1.6 论文研究内容和意义15-17
        1.6.1 论文研究内容15-16
        1.6.2 论文研究意义16-17
第二章 三维正交纤维增强复合材料的制作与准静态实验17-27
    2.1 原材料的选择17-18
    2.2 复合材料预制件的组织结构18-19
    2.3 三维机织正交结构织物预制件的织造19-20
    2.4 预制件成型20-23
        2.4.1 成型采用的材料21
        2.4.2 成型制作方法21-22
        2.4.3 成型后的复合材料板材22-23
    2.5 复合材料的准静态冲击测试23-24
        2.5.1 冲击破坏原理23
        2.5.2 冲击试验过程23-24
    2.6 冲击试验结果24-26
        2.6.1 载荷位移曲线24-25
        2.6.2 能量吸收曲线25
        2.6.3 破坏模式25-26
    2.7 本章小结26-27
第三章 三维机织正交结构复合材料参数化设计及有限元理论基础27-37
    3.1 参数化设计理论及基本形式27-29
        3.1.1 参数化设计的概念及原理27-28
        3.1.2 参数化模型的基本形式28-29
    3.2 三维机织正交结构复合材料的参数化设计29-30
    3.3 有限元法简介30-31
    3.4 ANSYS/LS-DYNA 及冲击接触理论基础31-36
        3.4.1 有限元软件ANSYS/LS-DYNA 简介31-32
        3.4.2 接触—碰撞数值计算方法32-33
        3.4.3 大变形理论数值计算33-36
    3.5 本章小结36-37
第四章 三维机织复合材料细观结构及其单胞模型的参数化建模37-46
    4.1 三维正交结构复合材料的细观结构37-41
        4.1.1 几何模型分析37-39
        4.1.2 模型中几何参数和宏观织造设计参数的关系39-41
    4.2 三维机织正交结构复合材料预制件模型的参数化实现算例41-44
    4.3 各结构的纤维体积含量44-45
    4.4 本章小结45-46
第五章 三维机织正交结构复合材料有限元模型的建立与模拟分析46-72
    5.1 选用PRO/E 软件与ANSYS 软件的接口程序46
    5.2 三维机织复合材料有限元模型的建立46-54
        5.2.1 问题定义及设定分析环境47
        5.2.2 几何模型的建立47-48
        5.2.3 单元选择48-49
        5.2.4 所采用的材料模型49-50
        5.2.5 网格划分50-53
        5.2.6 建立PART53
        5.2.7 定义接触信息53
        5.2.8 有限元建模需要注意的问题53-54
    5.3 施加边界条件与载荷54-55
    5.4 求解控制55
    5.5 K 文件的输出求解及修改55-56
    5.6 ANSYS/LS-DYNA 求解及分析进程控制56
    5.7 影响求解速度的因素及解决方法56-59
        5.7.1 时间步长的影响56-57
        5.7.2 加载速度的设置57-59
    5.8 有限元模拟结果的校验59-61
        5.8.1 实验与有限元模拟的载荷位移曲线对比59-60
        5.8.2 实验与有限元模拟的能量吸收位移曲线对比60-61
        5.8.3 实验与有限元模拟的破坏形式的对比61
    5.9 有限元模拟结果的分析61-71
        5.9.1 模型中有效应力云图61-63
        5.9.2 复合材料不同层面上单元的应力时间曲线63-68
        5.9.3 纤维增强体与基体之间的接触分析68-71
    5.10 本章小结71-72
第六章 结论72-74
    6.1 主要结论72-73
    6.2 展望与不足73-74
参考文献74-80
致谢80-81
附录81-84
论文发表情况84
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