A Summary of Damage Tolerance Specifications with Emphasis on Materials and NDI Requirements

摘要

Specifications for USAF military aircraft now include damage tolerance and durability as basic structural requirements. The introduction of these requirements into the design and development of future aircraft is briefly described. The new design analysis assumes the existence of flaws in the structure and considers their growth, at calculable rates, by appropriate cracking processes. Non-destructive inspection (NDI) intervals are then specified according to limits of safe crack growth. Airframe rework and repair requirements are similarly established for a period greater than the design life. Details of damage tolerance requirements, including flaw size assumptions, NDI intervals, etc., are summarized and illustrated. Under the new requirements, many existing aircraft are considered to be of uncertain structural integrity. The USAF is currently assessing damage tolerance and durability on a wide range of service aircraft. Application of the new requirements and methods of assessing damage tolerance in operational aircraft are described. (Author)