A STUDY OF FREQUENCY EFFECTS AND DAMAGE ACCUMULATION DURING THE FATIGUE OF GRAPHITE/EPOXY AND GLASS/EPOXY COMPOSITE MATERIALS (CREEP)
Abstract
The objective of this research is to understand the frequency effect on the fatigue behavior of graphite/epoxy and glass/epoxy composite materials. Fatigue tests were conducted on {(+OR-)45}(,(2s)) lay-ups ups using 0.05, 0.5 and 5 Hz frequencies. Basically the fatigue life increased as the loading frequency increased. Experimental results showed that the initial dynamic modulus of the composites is larger for glass/epoxy and graphite/epoxy composite laminates at high frequency. A nonlinear damage accumulation model is developed to describe the material properties degradation and predict the fatigue life at different stresses and frequencies. The frequency does not enter the model explicitly but only through the frequency effect on the initial modulus. The behavior of the dynamic strain and cyclic creep strain were tested as measures of fatigue damage.
Degree
Ph.D.
Subject Area
Materials science
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