Abstract
A new quantitative method, the D-index, is proposed to evaluate the departure of a given fibre arrangement from the completely spatial randomness (CSR) pattern. An explicit model which can effectively control the degree of randomness (DoR) is created to investigate the correlation between the D-index and DoR. The theory behind the correlation is analyzed followed by the derivation of first and higher order D-index with respect to the DoR under different fibre volume fractions. This may be the first time an accurate value of the departure from randomness is provided, which is considered important for accurate micro-mechanical analysis.