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Cyclic fatigue testing of adhesive joints : environmental effects.

Broughton, W R; Mera, R D (1999) Cyclic fatigue testing of adhesive joints : environmental effects. NPL Report. CMMT(A)192

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This report examines the combined effect of cyclic loading and environment (i.e. elevated temperature and heat/humidity) on the residual strength of adhesively bonded joints. Double-lap shear, tapered-strap and scarf joint configurations are considered. Residual strength/endurance limit data generated within the programme and obtained from industry have been assessed to determine any synergistic effects that may occur between cyclic loading and environmental agents (i.e. temperature and moisture).
Test data, supplied to the programme by Aerospatiale (courtesy of British Aerospace, Sowerby), from the ABHTA “Adhesives Bonding for High Temperature Applications” Brite-Euram Project BE-5104 have been analysed to determine the endurance limit of hot/wet conditioned double-lap joints. This work involved the combined effect of cyclic loading and temperature of moisture pre-conditioned bonded composite and metallic joints bonded with either epoxy FM 350NA or bismaleimide HP655 adhesives. A systematic approach can be used to determine intermediate residual strength or endurance limits, and to estimate knock-down factors for the individual actions or the combined effects of the degrading agents.
The work conducted on tapered-strap and scarf joints attempts to quantify knock-down (or correction) factors for the individual and combined actions of cyclic loading and hot/wet conditioning on joint strength. The results demonstrate that the complexity of determining design parameters to account for the combined effect of two or more degrading factors and there is a need to generate full S-N curves for design purposes rather than rely on a specific set of conditions to represent worst case scenarios.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CMMT(A)192
Subjects: Advanced Materials
Advanced Materials > Adhesives
Last Modified: 02 Feb 2018 13:18
URI: http://eprintspublications.npl.co.uk/id/eprint/1241

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