Polymeric stiffened sheet-like component and process for producing the same

A process for producing a polymeric stiffened sheet-like component, for example a panel, for aircraft construction. Production includes integration of hollow stiffening profiles, for example closed omega stringers, onto a sheet-like component, for example an external skin, where the stringers and external skin are produced from thermoplastic composite material. The stringers are integrated onto the external skin by establishing contact between the stringers and the external skin and melting thermoplastic composite material with exposure to heat and pressure at the areas of contact between external skin and stringers. Melting of the other sections of the stringers is avoided with a pressurized cooling fluid with a temperature significantly below the melting point of thermoplastic composite material, the fluid flowing through the airtight enclosed space in the stringers. Use of closed airtight thermoplastic omega stringers allows integration of the stringers onto the external skin in absence of any flexible tube within the stringers.