Effects Of Honeycomb Cell Size On Performances Of Sandwich Panels

Honeycomb sandwich materials with its unique structure and high-profilemulti-function characteristics by many materials scientists and engineers of favor, arewidely used in aviation, aerospace and other areas. Firstly this paper introduces brieflythe state of the development and application of the sandwich structure, and summarizedthe structure and performance characteristics of the sandwich structure. Then theprogress of research about the performance equivalent and the microstructure sizeinfluence of the sandwich structure in micromechanics is reviewed. On this basis, usingthe parameter design language of ANSYS to establish the3D finite element analysismodel, the effects of the cell size of the honeycomb sandwich panel in stiffness and heattransfer performance is revealed. The main research work in the dissertation will beintroduced as follows:Honeycomb sandwich panel was studied to reveal the effects of the cell size in thestatic analysis and the free vibration analysis．The response of the sandwich panel withthe homogenized cores was used as the standard of comparison． The ratio of theresponses of the detailed finite element models of sandwich panels to the correspondingcomparison solutions was defined as a Size Influencing Index that reflects theinfluences of the size variation of different cell configuration． Based finite elementtechnique，the static and the free variation response of honeycomb sandwich panels withthe different cores and the homogenized cores were analyzed comparatively，under threetypical boundary conditions． The computed results reflects the significant size effect ofthe honeycomb cell on the stiffness and the frequency behavior of sandwich panel．A computational model, Tri-layer Unit Cell(TUC) model, which can reveal theout-plane size variation of sandwich panel unit cell, is proposed to study the out-planesize effects of honeycomb sandwich panels. In this model, the three dimensional unitcell of sandwich panel, consisting of the upper and the lower skins and the homogenizedcore, is constructed based on homogenization method. It is compared with threemethods, i.e., homogenization method, the finite element method and the classicallaminated plate theory, to illustrate influences of the out-plane size variation onvibration and bending response of sandwich panel. Numerical results show that the proposed TUC model can characterize the out-plane size effects of sandwich panel withdifferent configuration cores. Significant differences between the homogenizationresults and the other two methods solutions demonstrate the limitations of thehomogenization method when the sandwich panel contains no more than three celllayers in out-plane direction.The numerical study is performed to reveal the influences of the cell size on thesteady-state thermal performance of hexagonal metallic honeycomb sandwich panel, byusing the semi-empirical Swann and Pittman formula and the finite element method,respectively. Based on the same material volume of honeycomb core, two types ofhexagonal honeycomb core are considered to establish the panel’s thermal analysismodel, which including the conduction and radiation coupling. Comparisons betweenthe temperature distribution results from both methods show that finite element methodcan reveal the size effect of the honeycomb cell on the thermal performances ofsandwich panel while the Swann and Pittman formula cannot fully. And the analysesbased on both methods also show that the temperature distribution of the lower surfaceof panel becomes gradually uniform when the wall thickness of hexagonal celldecreases.