FINITE-ELEMENT MODELING AND OPTIMIZATION FOR CONTROLLING THE RESIDUALTHERMAL-STRESSES OF LAMINATED COMPOSITE TUBES

The present paper describes the use of the laminated plate theory (LPT ) to optimize the architecture of laminated ceramic matrix composite t ubes possessing high thermal cracking resistance. The method estimates the induced thermal residual stresses of laminated composite tubes wi th various stacking sequences and laminae thicknesses, during cooling from a processing temperature of 1700 degrees C to room temperature us ing a general purpose finite element program ANSYS. The optimum struct ure of the ceramic matrix composite (CMC) tubes was achieved through c ontinuous iterative calls between the finite element output and an opt imization program. The design variables considered in this study are t he laminae thicknesses and the stacking sequences of various volume fr actions ranging from 0 to 40% of SiC whisker-reinforced mullite. An op timum design of the laminated composite tube consisting of four lamina e of [30/40/20/10] stacking sequence with the 40% layer on the inside surface and the 10% layer on the outside surface is achieved. This com posite architecture is found to have high thermal cracking resistance as compared to other design cases. (C) 1998 Published by Elsevier Scie nce Ltd. All rights reserved.