点阵夹芯圆柱壳抗屈曲性能模拟研究

发布时间：2018-05-16 11:59

本文选题：点阵夹芯 + 圆柱壳　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：点阵夹芯结构是指由两层蒙皮及中间点阵桁架组成的夹层结构,具有轻质高强、减震及隔热性能好、比模量高、可设计性好等优点,广泛应用于航空航天、船舶、建筑等诸多领域。本文通过建立参数与性能的关系,使用有限元分析方法讨论不同点阵参数的金字塔、四面体及KAGOME结构圆柱壳在外载作用下抗屈曲能力的差异。推导出了三种结构点阵单胞相对密度及等效模量与结构参数的关系式,并通过实验进行了验证。使用ANSYS workbench对点阵夹芯圆柱壳进行轴压及外压作用下的特征值屈曲分析,通过正交试验探求圆柱壳蒙皮厚度、单胞数量及杆件粗细对其结构整体抗屈曲能力的影响情况。在轴压及外压作用下夹芯圆柱壳的临界屈曲载荷与三种结构参数均成正相关,轴压作用下,圆柱壳的蒙皮厚度为影响其抗屈曲能力及承压效率的主要因素,芯子的作用十分微弱,三种点阵结构的抗屈曲能力差别不大,蒙皮厚度为3mm的圆柱壳抗屈曲能力明显强于蒙皮厚度为1mm和2mm时。外压作用下,圆柱壳蒙皮厚度的影响依然可观,但此时单胞数量及杆粗的影响也不容忽视,点阵单胞中杆件与蒙皮夹角为45°时,夹芯单胞拥有最高的等效模量,三种结构中,四面体结构拥有最佳的抗外压屈曲性能,点阵参数为蒙皮厚度3mm,单胞数量200个,杆粗4mm的夹芯圆柱壳临界载荷及承压效率最高。单胞数量为20×10,杆粗2mm的四面体点阵夹芯圆柱壳在蒙皮厚度大于3mm时,承压效率开始下降。在热载荷下,热屈曲的部位为热量集中最明显的外蒙皮,所以增多杆件数量或加粗杆件等一些利于换热的手段都会有效增强结构的抗热屈曲性能,相对的会减弱夹芯圆柱壳的隔热能力,影响结构抵抗热屈曲能力的主要参数为单胞数量,其次为杆粗,最后是蒙皮厚度。同时四面体结构的隔热能力最好,而KAGOME结构拥有最好的抗热屈曲性能。在热力耦合分析中,外压、轴压及热载荷等外载作用强度方差分析的F比分别为14.255、2.158、1.547,外压的作用最容易使圆柱壳发生屈曲,而热载荷及轴压的作用强度较低。
[Abstract]:Lattice sandwich structure is a sandwich structure composed of two layers of skin and intermediate lattice truss. It has the advantages of light weight and high strength, good shock absorption and heat insulation, high specific modulus, good designability and so on. It is widely used in aerospace and ship. Architecture and many other fields. In this paper, by establishing the relationship between parameters and properties, the difference of buckling resistance of cylindrical shells with different lattice parameters, such as pyramid, tetrahedron and KAGOME structure under external loading, is discussed by using finite element analysis method. The relationship between the relative cell density and equivalent modulus of three kinds of lattice cells and structural parameters is derived and verified by experiments. The eigenvalue buckling analysis of lattice sandwich cylindrical shells under axial and external pressure was carried out by using ANSYS workbench. The effects of skin thickness, cell number and rod thickness on the overall buckling resistance of cylindrical shells were investigated by orthogonal test. The critical buckling load of the sandwich cylindrical shell under axial and external pressure is positively correlated with the three structural parameters. Under axial compression, the skin thickness of the cylindrical shell is the main factor affecting its buckling resistance and compression efficiency. The effect of core is very weak, and the buckling ability of the three lattice structures is not different. The buckling ability of cylindrical shells with 3mm thickness is better than that with 1mm and 2mm. The effect of external pressure on the thickness of shell skin is still considerable, but the effect of cell number and rod thickness can not be ignored. When the angle between rod and skin in lattice cell is 45 掳, the core cell has the highest equivalent modulus. The tetrahedron structure has the best buckling performance under external compression. The lattice parameters are skin thickness of 3 mm, the number of unit cells 200, and the maximum critical load and compression efficiency of the sandwich cylindrical shell with thick rod 4mm. The pressure efficiency of tetrahedron lattice sandwich cylindrical shell with thick 2mm rod is 20 脳 10 when the thickness of the shell is larger than that of 3mm. Under the thermal load, the thermal buckling is located on the outer skin, which has the most obvious heat concentration. Therefore, increasing the number of bars or thickening the rods and other means conducive to heat transfer will effectively enhance the thermal buckling performance of the structure. The heat insulation ability of the sandwich cylindrical shell will be weakened relatively, and the main parameter affecting the thermal buckling resistance of the structure is the number of unit cells, the second is the rod thickness, and the last is the thickness of the skin. At the same time, tetrahedron structure has the best thermal stability, while KAGOME structure has the best thermal buckling performance. In thermodynamic coupling analysis, the F ratio of external load strength analysis of variance analysis of external pressure, axial pressure and thermal load is 14.255 / 2.1581.547, respectively. The effect of external pressure is the most likely to cause buckling of cylindrical shell, but the effect of thermal load and axial pressure is relatively low.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB303

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