变刚度复合材料层合板壳的分析与优化

发布时间：2018-09-06 17:48

【摘要】：与传统的直纤维层合结构不同,丝束变角度层合结构是一种铺层纤维角度连续变化的变刚度复合材料,通过铺丝头牵引着丝束带沿特定的轨迹运动,实现纤维的曲线铺放,使得纤维角度在同一铺层上连续变化,从而扩大了复合材料的设计灵活性,充分地利用纤维的方向特性,更好的改善结构性能和减轻结构重量。本文简述了变刚度复合材料层合结构的发展过程及国内外研究现状,以变刚度复合材料层合板壳为研究对象,在已有研究的基础上,通过设计丝束铺放轨迹,对其力学性能进行研究,主要工作如下:简述平移法和平行法这两种纤维铺放方式,分析容易出现间隙或者重叠区域的原因,综合比较两种方法优缺点选择平移法。介绍层合板(壳)的基本理论和序列响应面建模方法,选择二次函数造出响应面,再通过遗传算法优化获得原问题的优化解。设计变刚度层合板纤维曲线轨迹,通过连续曲线纤维离散化的思想建立了变刚度层合板的有限元模型,分析层合板在单向轴压和双向轴压载荷下纤维轨迹参数和几何参数对屈曲的影响。讨论纤维曲线轨迹和几何参数对层合板频率的影响,结合序列响应面法,对变刚度层合板的屈曲和频率特性进行优化,获得的T0、T1优化解。给出变刚度(椭)圆柱壳的纤维铺放路径和铺层顺序方案,在ANSYS中建立它们的有限元模型;在轴压,弯矩,扭矩载荷条件下,同时分析(椭)圆柱壳几何尺寸对屈曲性能的影响。然后以临界屈曲系数为目标,优化层合壳的屈曲特性。结果表明:在弯矩载荷作用下,用曲线纤维铺层θ代替[45/0/-45/90/-45/0/45/90]s层合壳中含有45°直线铺层,可显著提高圆柱壳的屈曲性能;通过控制丝束角度连续变化,改变椭圆柱壳圆周方向的刚度,达到适当的增加平坦部分的刚度,曲率半径小的那部分刚度适当减小,可以有效的提高椭圆柱壳的屈曲性能。
[Abstract]:Different from the traditional straight fiber laminated structure, the filament bundle variable angle laminated structure is a kind of variable stiffness composite material with continuous change of the fiber laying angle. The angle of the fiber changes continuously on the same layer, which expands the design flexibility of the composite, makes full use of the directional characteristics of the fiber, improves the structure performance and reduces the weight of the structure. In this paper, the development process of the composite laminated structure with variable stiffness and the research status at home and abroad are briefly described. Taking the laminated plate and shell of the variable stiffness composite material as the research object, on the basis of the existing research, the trace of the filament bundle placement is designed. The main work of this paper is as follows: the translation method and the parallel method are two kinds of fiber laying methods, the reason of the gap or overlapping region is analyzed, and the advantages and disadvantages of the two methods are compared synthetically. The basic theory of laminated plate (shell) and the modeling method of sequential response surface are introduced. The quadratic function is selected to create the response surface and the optimal solution of the original problem is obtained by genetic algorithm optimization. The fiber curve trajectory of the laminated plate with variable stiffness is designed. The finite element model of the laminated plate with variable stiffness is established by means of the idea of continuous curve fiber discretization. The effects of fiber locus parameters and geometric parameters on the buckling of laminated plates under uniaxial and biaxial loading are analyzed. The effects of fiber curve locus and geometric parameters on the frequency of laminated plates are discussed. The buckling and frequency characteristics of laminated plates with variable stiffness are optimized by using the sequential response surface method and the T0T 1 optimal solution is obtained. The fiber placement path and layering sequence of variable stiffness (ellipse) cylindrical shells are given, and their finite element models are established in ANSYS, under axial compression, bending moment and torque load, At the same time, the effect of geometrical dimension of cylindrical shell on buckling performance is analyzed. Then the critical buckling coefficient is taken as the target to optimize the buckling characteristics of laminated shells. The results show that the buckling behavior of cylindrical shells can be significantly improved by replacing [45 / 0 / -45 / 90 / -45 / 90] s laminated shells with 45 掳straight line layers with curved fiber layer 胃 under bending moment load, and by controlling the continuous variation of filaments angle, The buckling performance of elliptic cylindrical shells can be improved by changing the circular stiffness of elliptic cylindrical shells to increase the stiffness of the flat parts and decrease the stiffness of the parts with small radius of curvature.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33

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