Method of manufacturing a composite structure with prefabricated reinforcement element

A method of manufacturing a longitudinally extending composite structure including a shell part comprising a fibre reinforced polymer material including a polymer matrix and fibre material embedded in the polymer material, wherein the shell part is manufactured in a closed mould comprising at least a first outer mould part having a first forming surface and a second outer mould part having a second forming surface, wherein the method comprises the steps of:

• a) arranging a first fibre material in the first forming surface of the first outer mould part,
• b) arranging a pre-fabricated longitudinally extending reinforcement element, such as a beam or a web, on top of the first fibre material, the reinforcement element having a first side and a second side, and a first bonding surface and a second bonding surface, the reinforcement element being arranged so that the first bonding surface faces towards the first forming surface,
• c) arranging a second fibre material in the second forming surface of the second outer mould part,
• d) sealing a polymer foil above the second fibre material so as to retain the second fibre material against the second forming surface,
• e) closing the at least first outer mould part and the second outer mould part so as to form the closed mould, and so that the second bonding surface of the reinforcement element faces towards the second forming surface,
• f) forming a mould cavity by arranging a first vacuum bag between the first outer mould part, the second outer mould part and the first side of the reinforcement element, and arranging a second vacuum bag between the first outer mould part, the second outer mould part and the second side of the reinforcement element,
• g) evacuating the mould cavity,
• h) providing a resin in the mould cavity simultaneously with and/or subsequently to steps a) and c), and
• i) curing the resin in order to form the composite structure.