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Cyclic fatigue testing of adhesive joints: test method assessment.

Broughton, W R; Mera, R D; Hinopoulos, G (1999) Cyclic fatigue testing of adhesive joints: test method assessment. NPL Report. CMMT(A)191

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This report presents an experimental evaluation of three different test configurations to determine the suitability of the techniques for generating shear data under cyclic fatigue loading conditions. Single-lap, tapered-strap and scarf joint configurations were considered. The test methods were evaluated in terms of fitness for purpose in assessing fatigue performance and provides a guide to specimen geometry, manufacture and testing.
Constant amplitude (sinusoidal waveform) fatigue tests were carried out on all three test configurations in load control with the stress ratio R (oMIN/oMAX) equal to 0.1. Test frequency ranged from 5 to 25 Hz. The fatigue performance for each configuration can be represented by a linear-logarithmic (or by a power law) relationship that is dependent on the localised stress state of the adhesive in the bonded joint. The results indicate that peel stresses present at the ends of the bonded regions tends to govern fatigue resistance of bonded structures. Reducing peel stresses in these regions can be expected to extend the life of the bonded component.
The scarf joint exhibited excellent static performance, particular under compression loading, and cyclic fatigue characteristics, thus demonstrating the effectiveness of this configuration from a design perspective. The enhanced performance was attributed to low peel and shear stresses at the ends of the overlap. The tapered-strap joint, although less resistant to cyclic tension-tension loading, offers the potential for monitoring shear deformation under cyclic loading conditions and is compatible with standard extensometry.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CMMT(A)191
Subjects: Advanced Materials
Advanced Materials > Adhesives
Last Modified: 02 Feb 2018 13:18
URI: http://eprintspublications.npl.co.uk/id/eprint/1239

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