Fatigue and Fracture Behavior of Carbon Fiber Reinforced Plastic Under Combined Tensile and Torsional Stress and Influences of Water Absorption

Abstract

Static and fatigue tests of thin-walled, [+45] filament-wound tubular specimens of a carbon fiber reinforced plastic, T300/827, under combined axial tensile and torsional loading have been conducted, and the influences of water absorption on the failure behavior have been investigated. The tests were conducted under a load controlled condition keeping the combined stress ratio, α = τ/ σ. The static strength of dry specimens, which had been held in air, shows good agreement with the Tsai-Hill failure criterion. The static strength of wet specimens, which had been preconditioned in water for two months, at α = 0 - 1 decreased by water absorption, whereas at α = 2 - ∞, where compressive strength in the fiber direction dominates over the failure, a decrease in the strength of wet specimens from dry ones was small. Fatigue strength of dry specimens at α = 0 - 1 was smaller than those of α = 2 - ∞. This indicates that a combined loading mode influences the fatigue strength. A decrease in fatigue strength of wet specimens from air data at α = 0 - 0.5 was higher than those at α = 2 - ∞.