Temperature dependence of longitudinal tensile strength in unidirectional carbon fiber-reinforced plastic

This paper is concerned with the characteristics of the temperature-dependent tensile strength along the longitudinal direction of the unidirectional carbon fiber-reinforced plastic. The temperature-dependent tensile strength of the unidirectional carbon fiber-reinforced plastic was evaluated using resin-impregnated carbon fiber strand (carbon fiber-reinforced plastic strand) specimens with highly reliable co-cured tabs developed by the authors. The tensile strength of carbon fiber-reinforced plastic strand was measured at three constant temperatures below the glass transition temperature of the matrix resin for 50 specimens at each temperature. The results showed that the tensile strength of the unidirectional carbon fiber-reinforced plastic has a Weibull distribution at each temperature. The shape parameter of the tensile strength does not change with the temperatures and the scale parameter decreases clearly with increasing temperature. The degradation rate of the tensile strength of the unidirectional carbon fiber-reinforced plastic by the temperature raise against that of the viscoelastic modulus of the matrix resin agrees well with the predicted results based on the Rosen’s strength analysis.