Process for manufacturing highly stressed composite parts

A process for making a composite product in which reinforcement fibers are subjected to a composition based on a thermohardening resin and a photoinitiator appropriate to the irradiation by which the composition is to be treated. The resulting pre-impregnated material is introduced into a prepolymerization device, in which the pre-impregnated material is prepolymerized by appropriate irradiation. Lengths of the precomposite are applied to a support, the shape of which is dictated by the shape of one face of the composite part which is to be made, and are stacked one on another in a suitable number and placed snugly against the shape of the support, and the stack is subjected to final molding at a suitable pressure and temperature in order to polymerize the resin and to join the different lengths of precomposite.