|英文题名||Research on optimal design of honeycomb structure and its mechanical properties|
|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|
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.
|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.|