The standard shear-lag model is modified to allow for the determination of the stress concentration factors for any unidirectional intraply hybrid composite with random as well as deterministic arrangements of the filaments. Utilizing this micromechanical model in conjunction with the chain-of-bundles probability model, hybrids with different volume ratios of the constituents are analyzed. The method of analysis is the numerical Monte Carlo simulation technique. The well known "hybrid effect" for strains is confirmed. The Weibull distribution function is observed to be a good representation of the hybrid break ing strain. The estimated ultimate breaking strains show a significant improvement over previously cited results, and they appear to be more characteristic of experimental obser vations.
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