Reliability-based structural design of a representative wing and tail system together with structural tests

Abstract

Most reliability-based optimization studies focus on variables that are available in the design stage. However, it has been shown that inclusion of post-design measures, such as structural tests and health monitoring, can lead to better design choices. More recently, a new reliability-based design framework that can include both pre-design and post-design uncertainty reduction variables has been proposed in an earlier work. That earlier study focused on structural design of the most critical component of a civil aircraft and sought reliability-based optimization of the critical component together with its structural tests. The present study elaborates on that earlier study by including the system reliability considerations. A representative wing and tail system is considered in this study, and the most critical components of the wing and the tail are designed together with their corresponding structural tests. The number of coupon tests, the number of structural element tests, and the additional company knockdown factors for each component are selected as design variables to perform system reliability-based optimization for minimum direct operating cost. It is found that the optimum company knockdown factor for the wing is slightly larger than that of the tail, because a small fraction of the wing material is moved to tail for optimal reliability allocation. It is also found that the optimum number of structural element tests for the wing is larger than that of the tail. Finally, the optimum number of coupon tests for the wing is found to be slightly smaller than that of the tail. Copyright © 2011 by Erdem Acar.