【作者】 夏明凯；

【导师】 梁军；

【作者基本信息】 哈尔滨工业大学 ， 工程力学， 2011， 硕士

【摘要】 金属蜂窝夹层结构具有优异的力学性能,例如轻质、比刚度大、比强度高、隔热性能好等,因此被广泛地应用在火箭、卫星、飞机等航空航天领域。可是金属蜂窝夹层结构在其制备和服役过程中可能在不同位置会产生不同类型、形状和尺寸的随机缺陷,结构内的缺陷势必会对各项力学性能产生不利的影响,但是具有缺陷的金属蜂窝夹层结构能够满足使用过程中各项性能指标的要求仍具备服役能力。因此对含有缺陷的金属蜂窝夹层结构的继续服役能力做出有效评估是很有意义的。本文旨在对具有不同芯子缺失比例和不同面芯脱焊尺寸的缺陷对蜂窝夹层结构的力学性能的影响,实现的主要手段是数值模拟和理论推导的方法。本文第二章分别对含芯子缺失缺陷蜂窝夹层板进行了x和y方向的拉伸和压缩的数值模拟研究,以及对无缺陷结构的面内弹性模量的理论推导。蜂窝芯子缺失对金属蜂窝夹层结构的拉伸模量和拉伸强度几乎没有影响,压缩载荷作用下的x和y两方向的破坏模式是不同的。第三章对含有面芯脱焊缺陷的蜂窝夹层结构进行了共面和异面的力学性能的数值模拟研究,以及一些相关的部分理论推导。共面力学性能的模拟研究包括沿x方向的单双侧侧压模拟,单侧面芯脱焊的稳定性要好于双侧面芯脱焊,异面力学性能的模拟研究包括三点弯曲(其中跨距方向为结构的x方向),随面芯脱焊缺陷的增大金属蜂窝夹层结构的弯曲刚度和剪切刚度都随之下降,异面力学性能研究还包括平拉和平压的模拟研究,平拉载荷作用下随面芯脱焊尺寸近似呈线性衰减,面芯脱焊缺陷对平压载荷作用影响不大。为了表征金属蜂窝夹层结构面板与蜂窝芯子脱粘的损伤破坏模式,在论文第四章中基于内聚力模型建立了三维界面单元模型,通过利用ABAQUS用户子程序UEL开发了三维界面单元。通过确定面板与蜂窝芯子脱焊的张开位移与桥联应力的曲线,可以对面板与蜂窝芯子脱粘破坏进行数值模拟研究。更多还原

【Abstract】 Metal honeycomb sandwich panel has a few advantages, such as light weight, great stiffness, excellent insulation and so on. Because of these advantages, metal honeycomb sandwich panel is more and more widely used in rockets, satellites, aircraft and other aerospace applications. However, some defects with different types, shapes or sizes with occur in its preparation and service, and these defects have a negative impact on mechanical properties. But, metal honeycomb sandwich panel with defects meets the performance requirements. Thus, it is of great importance to assess the ability of constant service for the metal honeycomb sandwich panel. The paper gives the effect of different ratio between core missing and different dimension of surface-core connecting defect on the mechanical properties of sandwich structure. The aim of this paper is achieved by means of numerical simulation and theoretical analysis methods.The second chapter of this paper gives the numerical simulation results under the stretching and the compressing tests for this structure with part of the core missing in the x direction and the y direction, furthermore, we also made the derivation of the in-plane elastic modulus of the defect-free metal honeycomb sandwich panel in the two directions. Results show that honeycomb core missing has no effect on the tensile modulus and strength. Under the compression load, the failure modes in the two directions are different.The third chapter gives the numerical simulation results of the mechanical performance of the in-planer and the skew of the metal honeycomb sandwich panel with surface-core connecting defect. Also, we made some theoretical analysis. Mechanical performance of coplanar includes the compression in the x direction. One side of the structure have the surface-core connecting defect, which has the better stability than that both sides had the surface-core connecting defect. Mechanical performance of skew includes three point bending, the span for the x direction, both the bending stiffness and the shear stiffness of the metal honeycomb sandwich panel decrease along with the defect dimension increasing, and the skewed compressing and stretching, under the tensile load in the z direction, the strength of the structure is linear attenuation along with defect dimension increasing, however under the compression load the surface-core connecting defect has no effect on the structureIn order to characterize the failure modes of damage of the honeycomb sandwich panel on the surface-core debonding, we establish the three-dimension interface element model based on the cohesion model. By using ABAQUS user subroutine UEL we developed the three-dimension interface element. By determining the curve of the opening displacement with the bridging stress could simulate the debonding of the surface-core.更多还原