Sub-regional differentiated safety factors design method for aircraft structure

The structural safety factor of an aircraft, defined as the ratio of design load to service load, is a key parameter in aircraft design. Traditional design methods rely heavily on engineering experience, leading to subjective safety factor values and insufficient objectivity in quantifying uncertainties. For advanced aircraft requiring refined design, the uniform safety factor applied across all components results in overly conservative designs that limit ultimate flight performance. In order to solve this limitation, it is necessary to develop a sub-regional differentiated safety factor design method to better explore the material properties and design space on the premise of ensuring the reliability design requirements. In this paper, probabilistic reliability design optimization theory is used to study the uncertainty of the structural system, and the mapping relationship between structural reliability and sub-regional differentiated safety factors is established, and the design method of sub-regional differentiated safety factors is developed. Using the simplified engineering model of the wing-tip structure as an example, it is demonstrated that, assuming the design requirement of 99% structural strength reliability is met, the sub-regional differentiated safety factors in the majority of the structure's subregions are less than the unified safety factor of 1.45, resulting in a relatively lighter design weight of up to 3.926 kg.