Method for producing a composite material part by oriented needling of a preform

A method for producing a composite material part comprising continuous unidirectional fibers and a polymer matrix, comprising:

• a step of producing a preform formed of several superimposed plies, each ply being formed by continuous unidirectional fibers oriented along one fiber orientation to present a unidirectional fiber direction for each ply, said preform comprising plies of different fiber orientation such that different plies present different unidirectional fiber directions;
• a step of applying a non-woven felt comprising non-woven filaments to at least a first main face of the preform, the non-woven felt having a surface mass of between 5 g/m2 and 100 g/m2 and the non-woven filaments having a diameter of between 5 μm and 50 μm;
• and
• a step of needling said non-woven filaments by means of a needling device comprising a plurality of forked needles, each forked needle being provided at its distal end with a notch extending along a notch axis perpendicular to the main longitudinal axis of the forked needle, so that the non-woven filaments are captured by the notch and are driven by the forked needles through the preform to intermingle with the unidirectional fibers and are arranged within the preform in a known pattern by the step of needling the captured non-woven filaments in a direction substantially perpendicular in the z direction, wherein the captured non-woven filaments are driven and remain substantially perpendicular in the z direction relative to the plies of continuous fibers of the preform, said forked needles and the preform being arranged so that the notch axes form a non-zero angle with each fiber orientation during needling, wherein the notch axes orientation relative to the continuous unidirectional fibers minimizes driving or damaging the fibers of each superimposed ply layer, wherein each forked needle has a diameter of between 0.30 mm and 0.60 mm, wherein the notch has a width and a depth of between 0.03 mm and 0.1 mm, and wherein a needling density of the needling device is between 150 punches/cm2 and 350 punches/cm2;
• and
• a step of impregnating the dry preform with an impregnating polymer to form the composite material part, the impregnating polymer constituting the polymer matrix of the composite material part.