Composite structures durability design and substantiation

Abstract

An overview of the durability design requirements and substantiation approaches, with an emphasis on aerospace applications, is provided in this chapter. The service history of both commercial and military composite aircraft structures has provided numerous examples of both good and bad designs from which current design specification and guidance are derived. Issues to be considered in the design of composites used in primary and secondary composite structures including corrosion prevention measures associated with joining composite and metallic components are described. Design details, material selection, and demonstration that designs meet performance criteria are dependent on a structure's thermal and mechanical loading environments, service and economic life requirements, manufacturing constraints, and inspectability requirements. Based on an assessment of the durability of composite materials at the coupon level through modeling and testing, a description of the building block approach used to validate durability predictions of elements, subcomponents, components, and full-scale structural testing is given. The unique requirements for developing load spectra for accelerated full-scale durability testing for both composite and combined composite/metallic structures are discussed.