Abstract:

The relationship and difference between the allowables and the structural design allowables of composites are presented and their new definitions are given out. A review is completed on the development of determination methodology of the structural design allowables in the past more than twenty years. The additional requirements on the structural integrity of composite aircraft are described, particularly damage tolerance requirements. According to the additional requirements and the experimental study of the effects of various factors (impact damage, hot/wet, holes, delamination, fatigue and so on) on strength and fatigue life, the principles of determination methodology of the design allowables are introduced. In order to increase design allowables, several innovative structural design concepts (for example, textile composite preforms and RTM or RFI) are presented.

Key words: aircraft structure, structural integrity, damage tolerance, impact damage