3D-degenerated shell element for heat transfer analysis in shallow composite laminates

Shallow composites laminated shell possesses of widespread application in aerospace structural engineering, which becomes very complicated for its thermal analysis because of the heterogeneous and orthotopic natures and geometrically curved shape. So, only a few practical numerical techniques with refined fidelity for the analysis of structural heat transfer can be found. Considering that thermal load performs thermal shock, temperature function with a piecewise quadratic interpolation for temperature through the layers of composites shell was used. A coordinate transforming relationship between material coordinate, normalized parametric coordinate and structural global coordinate systems were established in details and the expression of temperature functions under different certain boundary conditions was proposed. A finite element numerical formulation of thermal analysis based on Galerkin principle was deduced, and a degenerated 3D shell element with fewer nodal parameters and high numerical precision was obtained, which not only improved the accuracy of thermal analysis but also saved CPU(center processing unit) running time. Its algorithmic code was carried out to test this formulation. It shows that the numerical result for a cone shell structure agrees well with those result obtained through brick element of ANSYS commercial software. This element will be used in large scale thermal analysis of aerospace structural design.