Compliant mechanisms fulfil a desired force and displacement characteristic. The development of such structures having a defined kinematical motion and subjected to several constraints, like deformability, stiffness and activation force is highly challenging. The present work deals with a methodology for analysing compliant mechanisms considering geometrically nonlinear deformations. By assembling pre-calculated nonlinear beam elements a new beam truss approach is introduced. The accuracy and quality of the mechanical model are verified by selected examples and compared to existing methods.