The development of a FEM structure solver for a coupled fluid-structure simulation is presented in this thesis. Different aspects were created to evaluate existing FEM libraries. The libMesh framework was considered to be best suitable and was used in the development of the program. Two different element types of flat shell elements were implemented, a three-node triangular and a four-node quadrilateral element. The shell elements were constructed by the superposition of plane and plate elements. For both, different existing models were considered. The developed program exists in two versions, one coupled version to be used in multi-physics simulations and a stand-alone version whose purpose was to validate the implemented finite element models. Every version is capable of being executed in parallel with MPI. The coupling environment preCICE is interfaced in the coupled program version. The validation of the elements showed good accuracy for the plane element components compared to analytical solutions as well as commercially available software. The plate element’s accuracy is lower compared to the plane elements due to the chosen models that have a simpler approximation of the physical circumstances. The superimposed shell element’s accuracy is well suited to be used in the structure solver. For both implemented element types, the accuracy can be increased by further subdividing the mesh structure. The parallelization test showed a good scaling with the number of processes for the assembly of the system’s matrix and right-hand side as well as for the solving step. In one coupling test, a fluidstructure interaction between the developed program and an external fluid solver was tested. The coupling via preCICE was successful. The developed structure solver showed good performance in the simulation and is qualified for further multi-physics simulations connected through preCICE.