To develop mechanical models of a material, it is necessary to determi
ne some of its intrinsic parameters. In the present study, we propose
different techniques for determining some dispersion parameters of fib
ers in composites, in a plane space. The results show on various short
fiber glass reinforced polypropylenes that are differentiated by thei
r fiber lengths, the evolution of the selected dispersion in relation
with the orientation and the granulometry of the fibers.