Probabilistic approach to safety factor evaluation for aircraft wing design

Abstract

Continuous growth of aircraft speed and altitude has a decisive influence on changes in their aerodynamic layout and structural-power diagrams, which leads to significant changes in the shape and thickness of wing profiles. The paper proposes a probabilistic-time approach to the solution of the actual problem of assessing the strength of a caisson wing structure. At the same time, a quasi-static methodology is used, according to which the probability of failure is considered at the most critical points, and the calculation is carried out at a fixed point in time, at which the loading of the wing structure is the most dangerous. The loads and load capacity of the wing in this approach are random values, which necessitates the use of statistical modeling in the calculations. On the basis of the authors' earlier researches, an engineering method of the strength calculation of the aircraft caisson wing has been developed, involving analytical and statistical modeling to estimate the influence of the safety factor on the probability of its non-failure operation. This methodology can be widely used in the design of aircraft as statistical material on the wing loads and its strength characteristics is accumulated. Numerical experiments based on Monte Carlo method for calculating the probability of no-failure operation of the caisson wing have been conducted. The dependences of the probability of no-failure operation on the safety factor for the most interesting, from the viewpoint of engineering practice, the non-failure range from 0.99 to 0.999 were obtained.