The influence of hygrothermal environments on the stress concentration in unidirectional composite lamina

Abstract

In this paper, the stress analysis of unidirectional composite lamina, containing aligned broken fibers and exposed to hygrothermal conditioning, is investigated. The governing equations are derived based on the modified shear-lag model and a proper micromechanic rule are used to consider the effect of temperature and moisture content on stress concentration factor (SCF) in composite materials. The results show that the SCF has been less affected by low temperature and moisture content while the hot/wet conditions have significant effect on it. At the high operational temperature levels, specifically near to the glass transition temperature and saturation state, it can be observed that the results are in a good agreement with the original shear lag model. The SCF decreases exponentially by increasing the fiber volume fraction in both in dry and hygrothermal conditions. Moreover, the effect of crack eccentricity and crack-tip matrix type on SCF has been evaluated in hygrothermal conditions.