Due to their special load carrying behavior, membrane structures are using the material most efficiently. As a consequence, the realized structures are extremely light but susceptible to flow induced effects. The missing bending stiffness results in a complex coupling of stress state and membrane shape. This necessitates special form finding techniques to determine the mechanically defined shapes of equilibrium as prerequisite of the analysis of prestressed lightweight structures. Due to the almost negligible mass of the structure, the surface-coupled, partitioned fluid-structure-interaction computations with an explicit coupling scheme fail. To achieve numerically stable results, an implicit coupling strategy using interfield iterations with under relaxation is applied and for the sake of efficiency, the Aitken's acceleration technique is used. A software environment with integrated form finding capabilities is proposed focusing on aspects related to the coupling strategies. Two examples of membrane structures in an idealized wind flow demonstrate the success of the approach.