Reinforcing material comprising twisted carbon threads for the manufacture of composite parts, and corresponding methods and use

A reinforcing material comprising:

• (a) a unidirectional reinforcing web formed of a plurality of carbon reinforcing yarns;
• (b) a layer of nonwoven material, comprising polymeric fibers affixed to each to each side of said unidirectional reinforcing web, said layers of nonwoven material comprising from 2 to 6% of the total weight of the reinforcing material;
• (c) wherein said reinforcing yarns each have a twist of 3 turns/m to 15 turns/m;
• and
• wherein all the carbon reinforcing yarns forming the unidirectional reinforcing web are individually twisted, the two possible directions of twist being denominated as either S-twist or Z-twist, and having a twist of 3 turns/m to 15 turns/m, the unidirectional reinforcing web comprising at least 3 carbon reinforcing yarns thus twisted with at least one S-twist reinforcing yarn and at least one Z-twist reinforcing yarn:
• wherein, when the total number of twisted carbon reinforcing yarns forming the unidirectional reinforcing web is even, the number of twisted carbon reinforcing S-twist yarns on one side of a plane Δ and the number of twisted carbon reinforcing S-twist yarns on the other side of the plane Δ, each of which is, independently, an integer in the range {[(total number of yarns)/4]−35%;
• [(total number of yarns)/4]+35%}, each endpoint of the range being rounded to the nearest integer if the formula defining it result in an integer, the other twisted carbon reinforcing yarns being Z-twist yarns;
• wherein, when the total number of twisted carbon reinforcing yarns forming the unidirectional reinforcing web is odd, the number of twisted carbon reinforcing S-twist yarns on one side of the plane Δ and the number of twisted carbon reinforcing S-twist yarns on the other side of the plane Δ, which are either two integers or two and a half integers, and are, each independently, in the range {[(total number of yarns)/4]−35%;
• [(total number of yarns)/4]+35%}, each endpoint of the range being rounded to the nearest integer or integer and a half if the formula defining it results in an integer or integer and a half, the other twisted carbon reinforcing yarns being Z-twist yarns;
• the plane Δ being the plane parallel to the general direction of extension of said unidirectional web and which divides said unidirectional web into two equal parts, being perpendicular to its surface.