Development of a Design Procedure for Aeronautical Structures Based on Reliability

In this paper, an approach to aeronautical structural design based on reliability analysis is presented. In this way, the concept of level of safety is discussed and methods of its calculation using statistical data are described. Based on the concept of level of safety, a design procedure is proposed. In order to validate this design procedure, two design cases are studied. In the first case study, using finite element method, a sandwich plate containing a circular disbond between the upper faceplate and core subjected to compressive in-plane load is examined. The calculated critical buckling load and its residual strength versus disbond diameter and design load versus level of safety are compared to the existing data a good agreement is achieved. In the second case study, a delaminated sandwich beam under bending load is considered and the design load (obtained from the strain energy release rate analysis) versus level of safety is determined. The results of the study show that for the adopted visual inspection technique and a high probability of damage occurrence, the design load should be about 25% of the beam strength to achieve a reliability higher than 0.99.