Method for producing structures made of thermosetting composite materials by assembling composite constituent parts moulded by injection infusion of liquid resin

A method for creating a structural part made of composite material by injecting-infusing a liquid, thermosetting resin into a fibrous reinforcement, the structural part comprising a first element and at least one second element. Both the first element and the at least one second element are created in an intermediate state during a distinct injection-infusion step associated with partial curing that is arrested at a degree of cross-linking of the resin below a gelling point of the resin. The first element and the at least one second element are held in a tooling, in a relative position and in a shape that the elements are to have in the structural part to be created, during an out-of-autoclave simultaneous complete curing phase so as to obtain a desired degree of polymerization of the resin of the first element and of the resin of the at least one second element.