Estimation of composite strength by a modified rule of mixtures incorporating defects

Inadequacy of the rule of mixtures to estimate the true values of composite properties having a large concentration of defects has led to numerous tests being performed costing time and money. Statistical average of the properties from the Weibulls distribution law has thus been relied upon so far for the design of composite structures. Yet, to estimate the properties of a fibre reinforced composite material having sufficient flaw densities due to the methodologies adopted for its processing, more so for fibres, has long been appreciated. To avoid this inadequacy a modified rule of mixtures is developed incorporating defect concentration in the fibre and matrix enabling to arrive at a more realistic value of the composite.