This paper describes the simulation approach for the analysis of fluid structure interactions(FSI) of rocket thrust chambers. It is based on a partitioned approach and includes several buildingblocks: codes for computational fluid dynamics (CFD) and computational structural mechanics(CSM) as well as techniques to handle non conforming surface grid and to solve the nonlinear coupledequations in time. One target application is the life time prediction and to simulate the structuralfatigue behaviour. Thus, cyclic loading conditions are important and are the motivation for a surrogatemodel, which is the focus of this contribution. It uses nonlinear mapping algorithms between surfacetemperature and heat flux in combination with a reduction of dimensionality via proper orthognal decomposition(POD). It can be used as a replacement of the time consuming CFD code and acceleratesthe FSI analysis several orders in time. Some applications regarding the validation of the FSI softwareenvironment finalize the description of the simulation approach showing that the simulation ofcomplex and multidisciplinary problems is laborious and needs a widespread understanding.