Determining Optimum Number Of Structural Element Tests For Wing, Horizontal And Vertical Tails

Abstract

Aircraft structural design is still performed using a deterministic design framework, within which the current practice to choose the number of structural tests for aircraft components is based on experience. This paper focuses on element tests among many different types of structural tests, and explores determination of the optimum number of structural element tests that must be performed for wing, horizontal tail and vertical tail by probabilistic methods. A representative system composed of a wing, a horizontal tail and a vertical tail is considered. It is assumed that the design of the wing and the tails are driven by their most critical components, which can be represented by a small region characterized by a width and a thickness. The widths of the critical components are kept constant and the thicknesses of these components are designed together with their corresponding number of structural element tests. The number of structural element tests and the additional company knockdown factors (that alter the design thicknesses) for each component are selected as design variables to perform system reliability-based design optimization (RBDO) for minimum direct operating cost.