IMECH-IR  > 非线性力学国家重点实验室
蜂窝结构优化设计及其力学性能研究
英文题名Research on optimal design of honeycomb structure and its mechanical properties
张丽
导师许向红
2018-05-25
学位授予单位中国科学院大学
学位授予地点北京
学位类别硕士
学位专业固体力学
关键词蜂窝结构 优化设计 压缩变形 弯曲性能 纤维复合材料
摘要

蜂窝结构具有高强、轻质、吸能、减震、隔音、隔热等优异性能,是轻量化设计在工程应用最广泛的结构之一,研究蜂窝结构力学性能至关重要。本文提出三种蜂窝结构设计方案,从理论分析和模拟出发,并结合实验,探究了三种蜂窝结构的抗压、抗弯性能;同时研究了体积分数和纤维类型对弯曲性能的影响。

1、设计节点增厚蜂窝结构。理论推导节点增厚蜂窝结构的等效弹性模量,研究节点参数变化对等效弹性模量的影响。通过蜂窝准静态单轴压缩实验、模拟,研究了胞元杆件的应力分布特征。结果表明,节点增厚蜂窝结构等效弹性模量理论值与实验、模拟值基本相符。在一定范围内,节点增厚蜂窝结构等效弹性模量、屈服应力高,杆件应力分布更加均匀。

2、设计非正六边形蜂窝结构。研究了长细比和斜杆角度对蜂窝结构的等效弹性模量及屈服应力的影响。通过数值模拟蜂窝准静态单轴压缩变形过程,探讨了胞元的变形特点。结果表明,长细比增加,蜂窝y方向的等效弹性模量及屈服应力增加;斜杆角度为20°时,蜂窝的抗压能力最高。蜂窝抗压能力提高时,非线性段胞元变形模式分为两个典型阶段:斜杆生产生较大刚性转动,形状变为凹角胞元;随后竖杆失稳屈曲,胞壁堆叠。

3、设计壁厚梯度蜂窝结构。通过数值模拟梯度壁厚蜂窝悬臂梁的弯曲过程,探讨了梯度壁厚和中空截面设计对其抗弯能力的影响。结果表明,胞元数相同,梯度壁厚蜂窝抗弯能力大于均匀壁厚蜂窝;空心设计的梯度壁厚蜂窝结构抗弯能力最好。梯度壁厚蜂窝的弹、塑性变形能大,边缘杆件厚,抗弯能力提高。

4、设计纤维复合材料。研究了体积分数、纤维类型、纤维材料、螺旋参数和结构尺寸对复合材料弯曲性能的影响。准静态三点弯曲实验结果表明,体积分数为5%,螺旋纤维和正弦纤维复合材料的弯曲性能大于直纤维;结构尺寸增加,纤维复合材料弯曲应力增加,但趋势不变,不影响其弯曲性能的对比结果。

英文摘要

As an important structure for lightweight design in engineering, honeycomb structure has excellent properties, including high strength, light weight, energy absorption, shock absorption, sound insulation, heat protection. It is an important structure for lightweight design in engineering. In this study, three kinds of optimized honeycomb structure scheme are proposed and its mechanical properties are investigated by theoretical analysis, numerical simulation and experimental test. Additionally, the influence of volume fraction, fiber form and material on the flexural capacity of the Fiber composites is also investigated.

1. The thickened joint honeycomb structure is optimized. obtained The compression elastic modulus of the thickened joint honeycomb structure was obtained and the influence of the thickened joint parameters on the elastic modulus was discussed. Quasi-static uniaxial compression experiment and simulation of honeycomb structure was conducted to study the stress distribution characteristics of cell edges. The results show that the mechanical properties of honeycomb obtained from theoretical analysis are in good agreement with that obtained from experimental and numerical results. The optimized thickened joint honeycomb structure has higher modulus of elasticity and the yield stress. Besides, the progressive collapse process is becomes more stable and the stress distribution of the edges becomes more uniform.

2. The non-regular hexagon honeycomb structure is optimized. This section theoretically studied the effects of the aspect ratio and the angle of the inclined edge the elastic modulus and yield stress. Then the deformation process of the honeycomb structure was invetigated by the quasi-static uniaxial compressionsimulation.  The results show that the elastic modulus and yield stress of the honeycomb in y direction increase with the increaseing of aspect ratio, and the compressive capacity of honeycomb is the highest when the angle of the inclined edges is 20°. When the compressive bearing capacity of the non-regular hexagon honeycomb structure is increased, the damage process of edge is divided into two stages: large rigid torsion deformation of the inclined edge, the shape of unit cell changed into reentrant cell; the vertica edge deflect and the unit cell is stacked together.

3.The gradient edge thickness honeycomb structure is optimized. This section studied the flexural bearing capacity of gradient edge thickness honeycomb structure by numerical simulation and the influence of gradient and hollow design on flexural bearing capacity was discussed. The results show that the bending stiffness and yield limit load of the gradient edge thickness honeycomb structure is greater than the hexagonal honeycomb structure with the same cell numbers; hollow honeycomb structure with gradient edge thickness has optimal bending bearing capacity. Hollow uniform and gradient edge thickness honeycomb structure has the same bending bearing capacity. The honeycomb with gradient wall thickness has large elastic and plastic deformation energy, thick edge and high bending resistance. The  edge thickness of the honeycomb cross section leads to the improvement of bending capacity.

4. The fiber composites with soft and hard combination is optimized. In this section,the effects of volume fraction, fiber type, fiber material, screw parameter and structural dimension on the flexural properties of composites were explored. The experimental results of three point bending quasi static compression test show that when the volume fraction is equal to 5%, the flexural capacity of the screw fiber and the sine fiber composites are both greater than that of the straight fiber composites. However, when the structure dimension decreases, bending stress of the fiber composites increases which does not affect the comparison result of its bending properties.

语种中文
文献类型学位论文
条目标识符http://dspace.imech.ac.cn/handle/311007/73180
专题非线性力学国家重点实验室
作者单位中国科学院力学研究所
推荐引用方式
GB/T 7714
张丽. 蜂窝结构优化设计及其力学性能研究[D]. 北京. 中国科学院大学,2018.
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