Bearing Response Characterization of Bolted Hybrid Composite Joints
Technical Report,01 Oct 2017,01 Oct 2019
AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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Composite materials are used in ever increasing quantities as aerospace and automotive applications demand lighter and stronger structures. However, a major issue that plagues composite materials is the process of attaching them to other structural elements. In many cases, fasteners are employed in addition to adhesives to make a more predictable joint. In other cases, fasteners are solely employed to create a serviceable joint or access panel. These fastener sites create stress concentrations and crack initiation sites in the brittle composite materials. In some systems, locally adding additional plies of the composite material is used. This is commonly called a pad-up. This does increase the local strength, but causes a large variation in thickness and fails to address the brittle failure characteristics of the material. The Steel Reinforced Advanced Thin Unitized Structure STRATUS Program lead by the Air Force Research Lab Aerospace Systems Directorate AFRLRQ proposes the addition of stainless steel foils between and in place of layers of composite near fastener sites Figure 1. This technology seeks to combine the high strength to weight ratio of carbon fiber composites with the predictable toughness and ductile failure nature of stainless steel.
- Couplers, Fasteners and Joints
- Laminates and Composite Materials