NUMERICAL FATIGUE LIFE ANALYSIS OF COMBUSTION CHAMBER WALLS FOR FUTURE REUSABLE LIQUID ROCKET ENGINES (LREs) APPLICATIONS

Kurzfassung

Within the presented manuscript the focus is towards maturing damage propagation simulation models of the regeneratively cooled combustion chamber (CC) inner liner, to gain an in-depth understanding of the interactions between influential elements including elevated temperature, cyclic conditions and the fatigue life mechanisms. A coupled thermal and structural 2D Finite Element Analysis (FEA) of a CC wall nozzle throat cross-section was set-up comprising the full cycle with pre-cooling, start-up, hot run, post-cooling and relaxation back to ambient temperature and pressure. The remaining useful life of the CC wall was estimated by a post-processing method including the cumulative effect of the fatigue damage and tensile strain accumulation. The proposed accumulative damage model for the low cycle fatigue (LCF) analysis consists of a model’s combination in accordance with Bonora-Gentile-Pirondi (2004) and Dufailly-Lemaitre (1995). Contrary to conventionally proposed studies with damage parameter values integrated as state variables in the FEA, we propose an alternative approach by introducing the damage parameter in the post processing method to save numerical analysis time. The integration of a directional progressive accumulation of plastic strain in cyclic thermo-mechanical loading, is especially important for rocket engine components during their test phase, as well as to increase the reusability capacity of the future reusable launch vehicles (RLVs).