22 April 1996 Development of smart structural attachment fixtures
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Abstract
This paper discusses efforts related to the development of smart bolts to be used as structural attachment fixtures. The work has been directed at meeting the high-strength application requirements for the aircraft industry and selected applications within the construction industry. The bolts are fabricated from metastable austenitic steel materials which progressively and irreversibly transform from a nonferromagnetic, austenitic parent phase to a thermodynamically stable, ferromagnetic martensitic phase as a function of applied strain. Thus, the ferromagnetic response of a bolt in service can be used to indicate the degree of inelastic deformation, i.e., the peak strain, that the bolt has experienced up to that particular point. A combination of bolt alloy chemistry and thermomechanical treatment has been utilized to produce a sharp ferromagnetic response with respect to small plastic deformation strains. The extreme strength of the materials allows for a centrally drilled access hole for the placement of sensitive Hall sensor probes to detect any inelastic material behavior along the length of the bolt without removal from the structure. A discussion of the smart materials behavior of the bolts will be followed by a presentation of recent test results which illustrate the structural bolt monitoring technique with some possible applications.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Larry D. Thompson, Bruce D. Westermo, "Development of smart structural attachment fixtures", Proc. SPIE 2719, Smart Structures and Materials 1996: Smart Systems for Bridges, Structures, and Highways, (22 April 1996); doi: 10.1117/12.238828; https://doi.org/10.1117/12.238828
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