Composite connecting rod having an increased mechanical strength

1. A method of fabricating a connecting rod ( 6 - 6 ″) out of composite material from three-dimensional fabric of woven reinforcing fibers, the connecting rod ( 6 - 6 ′″) extending in a main direction (AX), and the method comprising the operations of:

cutting out two or more base pieces ( 7 - 7 ′″, 8 - 8 ′″) from one or more different three-dimensional fabrics;

cutting out two or more reinforcing pieces ( 9 - 9 ′″, 10 - 10 ′″) from one or more different three-dimensional fabrics;

installing the two or more base pieces and two or more reinforcing pieces ( 7 - 7 ′″, 8 - 8 ′″, 9 - 9 ′″, 10 - 10 ′″) on a support in order to shape the base pieces and reinforcing pieces in a configuration in which the base pieces and the reinforcing pieces are superposed;

securing the two or more base pieces and two or more reinforcing pieces ( 7 - 7 ′″, 8 - 8 ′″, 9 - 9 ′″, 10 - 10 ′″) to one another by stitching ( 12 - 12 ′″, 13 - 13 ′″, 14 - 14 ′″, 15 - 15 ′″) with reinforcing fibers in order to constitute a reinforcing fiber preform;

installing the preform on a mandrel; and

injecting resin into the preform and polymerizing the resin,

wherein the two or more base pieces and the two or more reinforcing pieces ( 7 - 7 ′″, 8 - 8 ′″, 9 - 9 ′″, 10 - 10 ′″) are secured to one another by means of at least one operation of stitching together a pair of edges ( 7 a , 8 a , 7 b , 8 b ) extending along the main direction (AX), the edges belonging to two distinct base pieces ( 7 - 7 ′″, 8 - 8 ′″) in order to secure said two distinct base pieces to each other.

2. The method according to claim 1 , wherein the two or more base pieces and two or more reinforcing pieces ( 7 - 7 ″, 8 - 8 ′″, 9 - 9 ′″, 10 - 10 ′″) are secured to one another by means of at least one operation of stitching a reinforcing piece ( 9 - 9 ′″, 10 - 10 ′″) against a base piece ( 7 - 7 ′″, 8 - 8 ′″) in order to secure said reinforcing piece and said base piece to each other.

3. The method according to claim 1 , wherein the edges that are assembled together by stitching are of complementary chamfered shapes in a region where they are stitched together.

4. The method according to claim 1 , wherein a single stitching operation is performed to secure two edges of two base pieces ( 7 ″, 8 ″) to each other and to a reinforcing piece ( 10 ″).

5. The method according to claim 1 , wherein a single stitching operation is used to secure two edges of two reinforcing pieces ( 9 ″, 10 ″) to each other and to a base piece ( 7 ″).

6. The method according to claim 1 , wherein the two or more base pieces and the two or more reinforcing pieces ( 7 - 7 ′″, 8 - 8 ′″, 9 - 9 ′″, 10 - 10 ′″) are secured to one another by means of at least one operation of stitching a reinforcing piece ( 9 - 9 ′″, 10 - 10 ′″) against a base piece ( 7 - 7 ′″, 8 - 8 ′″) in order to secure them to each other.

7. The method according to claim 1 , wherein two base pieces ( 7 ′, 8 ′) and two reinforcing pieces ( 9 ′, 10 ′) are used to make up the preform, and wherein the two or more base pieces and two or more reinforcing pieces ( 7 ′, 8 ′, 9 ′, 10 ′) are secured to one another by at least one operation of stitching together two pairs of superposed edges extending in the main direction (AX), the edges of one of the pairs belonging to two different base pieces ( 7 ′, 8 ′), and the edges of the other pair belonging to two distinct reinforcing pieces ( 9 ′, 10 ′), and wherein said two pairs of superposed edges are stitched together ( 14 ′, 15 ′) jointly.

8. The method according to claim 7 , wherein the edges that are assembled together by stitching are of complementary chamfered shapes in a region where they are stitched together.

9. A method of fabricating a connecting rod ( 6 - 6 ′″) out of composite material from three-dimensional fabric of woven reinforcing fibers, the connecting rod ( 6 - 6 ′″) extending in a main direction (AX), and the method comprising the operations of:

cutting out two or more base pieces ( 7 - 7 ′″, 8 - 8 ′″) from one or more different three-dimensional fabrics;

cutting out two or more reinforcing pieces ( 9 - 9 ′″, 10 - 10 ′″) from one or more different three-dimensional fabrics;

installing the two or more base pieces and the two or more reinforcing pieces ( 7 - 7 ′″, 8 - 8 ′″, 9 - 9 ′″, 10 - 10 ′″) on a support in order to shape the base pieces and reinforcing pieces in a configuration in which the base pieces and the reinforcing pieces are superposed;

securing the two or more base pieces and the two or more reinforcing pieces ( 7 - 7 ′″, 8 - 8 ′″, 9 - 9 ′″, 10 - 10 ′″) to one another by stitching ( 12 - 12 ′″, 13 - 13 ′″, 14 - 14 ′″, 15 - 15 ′″) with reinforcing fibers in order to constitute a reinforcing fiber preform;

installing the preform on a mandrel; and

injecting resin into the preform and polymerizing the resin,

wherein two base pieces ( 7 ′, 8 ′) and two reinforcing pieces ( 9 ′, 10 ′) are used to make up the preform, and wherein the two or more base pieces and the two or more reinforcing pieces ( 7 ′, 8 ′, 9 ′, 10 ′) are secured to one another by at least one operation of stitching together two pairs of superposed edges extending in the main direction (AX), the edges of one of the pairs belonging to two different base pieces ( 7 ′, 8 ′), and the edges of the other pair belonging to two distinct reinforcing pieces ( 9 ′, 10 ′), and wherein the two pairs of superposed edges are stitched together ( 14 ′, 15 ′) jointly.

10. The method according to claim 9 , wherein the edges that are assembled together by stitching are of complementary chamfered shapes in a region where they are stitched together.