Numerical approach to calculate thermal expansion of honeycomb sandwich panel with composite face sheets

The aim of this paper is to show an accurate method to predict thermal defo rmations of honeycomb sandwich panels having composite skins. First of all, some problems of the conventional method using the laminate theory are poi nted out. In order to develop an effective predicting method, a model on de tailed structure of a unit cell for sandwich panels is developed utilizing the 3D finite element method. A periodic boundary condition is introduced t o the model to represent the repetitive structures of the sandwich panel. T he effective elastic modulus of the cell foil is obtained from the result o f an out-of-plane compressive test on the honeycomb core. The adhesives bet a een skin and core is modeled by considering its shape and quantity. The d ifference between the CTE according to this model and the actually measured one is approximately 0.1 x 10(-6)/K;. The paper further attempts to explai n the anisotropic character of the sandwich panel. The result of this analy sis suggests that the direction-dependency of the CTE is underestimated wit h the fact that the effective elastic modulus at a portion where a ribbon i s bonded with another one is different from the effective elastic modulus a t a portion where the ribbon is on its own.