Abstract: Load spectrum is a basis for durability design, analysis and testing, and has always been one of the core issues of military aircraft structural durability research. To conduct the fatigue life evaluation and extension, the durability severe spectrum has been recommended in the Jointed Service Specification and Guideline JSSG-2006 and Chinese national military standard GJB 67.6A-2008, becoming a hotspot in both domestic and foreign load spectrum research because of its multiple advantages compared to the average spectrum. To serve the research and development of aircraft models, this paper systematically summarizes the status of durability severe spectrum development and applications under the guidance of relevant standards and specifications. First, the concept of severe spectrum is elaborated, two types of load spectra and corresponding scatter factors used for life evaluation and extension are summarized, and the determination method of the severity of the severe spectrum are introduced. Secondly, the developing methods and applications of the severe spectrum are reviewed. Finally, the technical challenges and future research directions of severe spectrum development and application are pointed out.

Key words: durability, severe spectrum, fatigue, aircraft structure, average spectrum, scatter factor