Method of producing a composite shell structure

Method of producing a composite shell structure in form of a wind turbine blade shell part comprising a reinforced fibre material embedded in a cured resin and comprising the following steps:

• A providing a first mould part having a preferably substantially concave mould part moulding surface with a contour defining an outer surface of the composite shell structure;
• B providing a perform forming part having a preferably substantially convex and substantially upwardly facing preform forming surface being shaped essentially complementary to at least a part of the first mould part moulding surface;
• C forming a preform by arranging a dry fibre material comprising a number of dry fibre layers on the preform forming surface;
• D bringing the first mould part and the preform forming part together to an assembled position so that the first mould part moulding surface faces the preform forming surface and a cavity is defined between said surfaces and substantially accommodates the fibre material arranged on the preform forming surface of the preform forming part;
• E transferring the preform to the first mould part by releasing the fibre material from the preform forming surface so that it is received on the moulding surface of the first mould part;
• F removing the preform forming part from the first mould part;
• G forming a mould cavity by means of a second mould part arranged on top of the fibre material;
• H curing and/or allowing the resin to cure;
• and
• wherein resin is supplied to the mould cavity following step G, wherein the second mould part is a flexible mould part formed of a flexible material, preferably a polymer film, and wherein—prior to step C—the flexible mould part is arranged on the preform forming surface.