Effects of Proof Test on the Strength and Fatigue Life of a Unidirectional Composite
SourceThe effects of a static proof testing on the statistical distribution of the static strength and fatigue life of a unidirectional graphite-epoxy laminate (AS-3501-05) are investigated experimentally. Loading mode for both the static and fatigue tests is restricted to uniaxial tension in the fiber direction. Six-ply tension coupons with dimensions of 22.9 cm by 1.9 cm are used; and all tests are conducted using a closed-loop Instron tester, under room temperature (∼21°C) and ambient humidity (∼60% percent relative humidity) conditions. Test data are analyzed by means of a two-parameter Weibull distribution in conjunction with the maximum likelihood method for parameter estimation. Results show that proof testing can guarantee a minimum static strength, and to a lesser degree, the method can also assure a minimum fatigue life.