Effect of loading path on fatigue degradation and stress-strain response of glass fabric composites under tension/torsion biaxial cyclic loading
Kawakami Hiroshi; Tamiaki Minoru; Fujii Toru
Abstract:The present paper shows the effect of loading path on the fatigue degradation of plain woven glass fabric polymer matrix composites under tension/torsion biaxial loadings. The loading path significantly affected the fatigue characteristics at low cyclic fatigue. The effect of loading path on the fatigue strength and the modulus decay in shear with respect to the number of loading cycles was most significant when the normal stress was applied longer for each loading period. For such cases, the fatigue life became short and the shear modulus decreased much during an early stage of fatigue. The loading path also affected the internal damage accumulation. The matrix cracks were curved when the stresses were not applied proportionally. Peculiar phenomena were also observed in normal stress - normal strain curves both in tension and shear. A model was proposed to explain the phenomena. On the contrary, the effect of loading path on the fatigue characteristics was not distinguishable at high cyclic fatigue. Key Words:biaxial loading, loading path, stress-strain relation, modulus decay, fatigue strength,@low cyclic fatigue, high cyclic fatigue