Minimizing thermal residual stresses in C/SiC functionally graded material coating of C/C composites by using particle swarm optimization algorithm

The thermal residual stresses (TRSs) induced in C/SiC functionally graded material (FGM) coating of carbon/carbon (C/C) composites when cooling down from the processing temperature have a significant influence on the oxidation resistance of composites. The objective of this work is to minimize the TRS in the coating by controlling the thicknesses and compositional distribution of the C/SiC FGM. The solution approach combines two analyses: (a) an analytical model based on force and moment balances is implemented to determine the TRS; (b) a particle swarm optimization (PSO) algorithm is interfaced with the analytical model to find an optimal design and thereby significantly reduce the TRS within the coating. The classical PSO algorithm is modified to satisfy the limits of the optimization variables. In order to obtain the feasible optimal solution, a method derived from the harmony search algorithm is used. Satisfactory results are obtained and the results indicate that the compositional distribution has an important influence on the TRS and a critical value of the compositional distribution exponent exists.