繰り返し荷重下における平織炭素繊維布強化複合材料の損傷分布と損傷進展挙動

概要

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The concept of 'Damage Unit' was employed to describe the fatigue damage of plain-woven carbon/epoxy composites and its progression. How the cluster formation of damage units and the distribution of damage units affected the fatigue damage progression behavior was studied. The thermoelastic damage analysis (TDA), which is one of non-destructive testing techniques for damage evaluation, was conducted to evaluate the fatigue damage state in the specimen during fatigue testing. Internal damage state was also observed on the polished edge-wise surface with a SEM. The experimental results showed that the size ratio of the maximum damage unit cluster Cmax rapidly increased after the damage unit ratio p exceeded 0.527, called as "percolation threshold",pc. The final failure occurred because local delamination , fiber breakage and accumulation of transverse cracks widely occurred in the specimen after p exceeded pc. Since the relationship between averaged thermoelastic damage response and Cmax was nearly linear, fatigue damage progressed due to formation of damage unit cluster. The fractal dimensions of the damage unit distribution D increased to be a steady state value after p exceeded pc. These results indicated that fatigue damage progression was accelerated when D increased beyond a steady state value.
日本実験力学会の論文