Discussion on the determination of small-load truncation level of aircraft structural fatigue load spectrum

Abstract

As an important part of the fatigue load spectrum simplification of aircraft structures, the small-load truncation can significantly save the time and cost of fatigue tests. However, there is no widely accepted standard method for determining the small-load truncation level. In this paper, the existing small-load truncation levels in the literature are collected and divided into two determination methods, which are based on the material fatigue limit and the spectral maximum load. The links between the two determination methods are explored. The relationship model of the small-load truncation levels is established. The results show that the two methods are the same in essence,and the latter is an extension of the former combining the characteristics of aircraft loads and structural materials.The relationship model established between the small-load truncation levels could provide helpful references for the determination of the small-load truncation levels in the engineering fatigue load spectrum simplification.

Keywords

• small-load truncation level
• load spectrum simplification
• fatigue test
• structural verification
• fatigue limit