A composite has a Young Solution Young\'s modulus of material = 85 GPa Young\'s modulus of carbon fibre = 355 GPa Young\'s modulus of polymer matrix = 2 GPa assuming linear behavior of the materials in a cross-section, that is area occupied by the material has the strength of that material only x is the percentage of carbon fibre in the cross section 1-x is the percentage of matrix in the cross-section Thus, 85 = 355x + 2*(1-x) x= 0.2351 Therefore, minimum volume fraction as a percentage of fibers = 23.51% .