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Flexural Fatigue Behavior of Thick Glass/Epoxy Composite Flex Beam

WEN XIONG, SUONG V. HOA

Abstract


In this paper, a clamped load-applying fixture was used for cyclic flexural bending test. A simple rectangular glass fiber epoxy specimen with bolted holes was subjected to flexural fatigue loading. The flexural fatigue test was conducted under displacement control at 3Hz, with a R-ratio of 0.1 (single sided bending). The fatigue behavior was observed for two stacking sequences: [0]80 and [0/90]20s. For each type, the specimens were subjected to two deflection levels: 60% and 70% of the ultimate displacement. Thermography was used to record the surface temperature increase, focusing on the crack initiation area. A crack was indicated through three ways: sound, visual observation and thermography. A 20% reduction of initial load was taken as a failure criterion. At 60% level, the [0]80 test specimens did not initiate cracks until failure. The [0/90]20s test specimens initiated cracks at 10% of fatigue life. At 70% level, the [0]80 test specimens initiated cracks at 25% of fatigue life while the [0/90]20s test specimens initiated early on fatigue life.

Keywords


thick composite, flexural fatigue, crack propagation, thermography.Text

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