Method for designing a composite material part with a curved surface

A method implemented on a computer having a memory and a processor coupled to the memory for designing a composite material part with a curved surface (65) to which a plurality of stiffening elements oriented in planes substantially perpendicular to said curved surface are joined, including a design of a three dimensional (3D) fabric model defining contours of fabrics which are to be stacked to shape said composite material part from geometric references relating to said part with a curved surface (65) and to said stiffening elements, said design of the 3D fabric model comprising the following steps:

• generating, using the processor, references (51) of the curved surface in 3D, the references (51) comprising an intersection curve for each stiffening element including intersections between a plane of the stiffening element with a support surface, including as many raised surfaces (53) per intersection created between the planes and the support surface;
• generating, using the processor, a planar surface (63) developed in two dimensional (2D) corresponding to the curved surface (65) of the part in 3D and generating geometric references (71) in 2D corresponding to the references (51) of the curved surface in 3D, said generating including creating raised surfaces (59) in 2D per intersection of the stiffening element with the support surface;
• associating the planar surface (63) developed in 2D with the curved surface (65) in 3D and associating the geometric references (71) with, the corresponding references (51) of the curved surface in 3D, such that any action in one of the surfaces is reflected in the other, said associating including creating junctions in pairs in the raised surfaces (53, 59) obtained in 3D and 2D, resulting in a composite surface (61) with two domains, one domain in 3D and the other domain in 2D, per stiffening element;
• computing the fabric model in the surface (63) developed in 2D;
• and
• carrying out any subsequent modification of the fabric model either in the surface (63) developed in 2D or in the curved surface (65) in 3D,
• wherein an intersection point (69) is a reference point which changes selection between the 2D domain and the 3D domain, and
• wherein at least some of the steps of said method are performed using said processor.