In this paper, an improved version of Jaya algorithm, called iJaya, is proposed to optimize the fiber orientation of the stiffened composite plate. The improvement has been executed in the selection step of the original algorithm, in which one-third of the next population is chosen by the original procedure, while two-thirds are selected by the elitist technique. This way of modification aims at effectively balancing the exploration and exploitation capabilities of the algorithm and lead to the improvement in convergence rate. The improved algorithm is also proven to effectively handle optimization problems with both continuous and discontinuous variables.

The iJaya algorithm is then applied to solve the optimization problem of the stiffened composite plate with the design variables are the fiber angles and the objective function is the strain energy of the plate. The Numerical results obtained from solving optimization problems show that iJaya outperforms some other methods and prove the effectiveness and the efficiency of the proposed method.