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Abstract
A computer-controlled test apparatus (CCTA) and other instrumentation for subjecting sealant specimens to cyclic fatigue during outdoor exposure was developed. The CCTA enables us to use weather-induced conditions to cyclic fatigue specimens and to conduct controlled tests in-situ during the outdoor exposure. Thermally induced dimensional changes of an aluminum bar were fed to a computer that enhanced the movement, set limits on the movement, and supplied movement information to the test apparatus. As specimens moved, load/deformation and weather conditions (temperature, relative humidity, UV radiation, precipitation, and wind velocity) were measured every few minutes to give an extensive database containing these variables. In addition, controlled tests were done every four hours during the exposure. At these four hour intervals, the computer was programmed to interrupt weather-induced cyclic fatigue and conduct a standard-strain test. The data enabled us to calculate the elastic modulus of each specimen at any time during the exposure and to construct a model that fit the observed temperature and relative humidity effects on modulus.
Keywords
Service life,
accelerated life testing,
sealing compounds,
deterioration,
weathering,
timber joints,
testing,
fatigue,
joints,
mechanical properties,
elasticity,
modulus of elasticity,
temperature,
humidity,
ultraviolet radiation,
strains,
stresses,
precipitation,
calking,
accelerated testing,
failure,
exposure tests,
stiffness,
aging,
durability,
dimensional stability
Citation
Williams, R. Sam; Lacher, Steven; Halpin, Corey; White, Christopher. 2009. Evaluating cyclic fatigue of sealants during outdoor testing. Service life prediction of polymeric materials : global perspectives. New York : Springer, 2009: pages 129-151: ISBN: 0387848754: 9780387848754.
