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Abstract
Ultraviolet radiation, moisture, heat, and cyclic fatigue are some of the stressors that cause materials to degrade outdoors. Considerable research has addressed the effects of ultraviolet radiation and moisture on the rate of this degradation. An often overlooked stressor on materials, during outdoor testing, is the cyclic fatigue. Cyclic fatigue is caused by self-induced dimensional change of a material or by dimensional change of materials in contact with it. For example, changes in the moisture content of wood cause it to shrink and swell, which leads to surface checking; dimensional change of wood may cause paint to crack or sealants to debond. In our research on the service life prediction of sealants, we have developed a computer-controlled test apparatus and accessory instrumentation to subject materials to cyclic loads and to measure their degradation as they are tested. The changes in elastic modulus, temperature dependence of the modulus, plasticizing effect of water above and below freezing, and evaluation of specimen quality at the beginning of the test were made possible using this equipment.
Keywords
Elasticity,
modulus of elasticity,
temperature,
testing-machines,
accelerated life testing,
service life,
sealing compounds,
weathering,
fatigue testing machines,
moisture,
fatigue,
swelling,
shrinkage,
accelerated testing,
building materials
Citation
Williams, R. Sam; Lacher, Steve; Halpin, Corey; White, Christopher. 2006. Evaluation of materials during outdoor testing using a computer-controlled test apparatus. Proceedings of the Fifth International Woodcoatings Congress : Enhancing Service Life, 2006 October 17-18, Prague, Czech Republic. Middlesex, UK : PRA Coatings Technology Centre, c2006: 25 p.: ISBN: 9780955131745: 095513174X
