SUMMARY

In this thesis, several RBDO method and algorithms for airplane floor grid layout optimization have been proposed. Copula has been introduced to model random variable correlations and to be applied to produce correlated data samples for Monte Carlo simulations. Based on HL method, a correlated HL method is proposed to evaluate reliability index under correlation. As an alternative method for computing reliability index, reliability index is interpreted as an optimization problem and a nonlinear programming algorithm is introduced to evaluate reliability index. To evaluate the reliability index by Monte Carlo simulation in a time efficient way, a kriging based surrogate model is proposed, comparison has been made between the original model and surrogate model in terms of computing time. Since in RBDO optimization models, the reliability constraints usually do not have analytical form, a heuristic gradient based direct searching algorithm and a regression based response surface method is proposed. These methods and algorithms have been applied to the layout optimization of aircraft floor grid structural design.