📚 Eksplorasi & Komparasi Topik Dokumen

DEVELOPMENT OF A NUMERICAL FRAMEWORK FOR FITNESS FOR SERVICE ASSESSMENT OF FATIGUE CRACK GROWTH IN STEAM TURBINE COMPONENTS

Steam turbines are critical components in geothermal power plants because their reliability directly affects power generation continuity. Turbine blades operate under centrifugal load, steam pressure, cyclic excitation, wet steam, and corrosion, which may promote pitting and fatigue crack growth. Once a pit behaves as a crack like flaw, the component requires a defect based assessment to estimate whether it can continue operating safely. This research develops a numerical framework for Fitness for Service (FFS) assessment of fatigue crack growth in steam turbine components. The framework integrates steady computational fluid dynamic (CFD) pressure loading, global finite element analysis (FEA), local cracked submodeling, stress intensity factor (SIF) post-processing, and Paris law based remaining life calculation. A simplified American Iron and Steel Institute (AISI) grade 410 steam turbine blade was used as the main assessment case. The CFD pressure field was applied using a blade passing frequency (BPF) based pressure multiplier to represent cyclic pressure fluctuation. The global model identified the critical stress hotspot, while the local extended finite element method (XFEM) cracked submodel was used to calculate mixed mode stress intensity factors. The result shows that the blade crack reaches the critical region between 6 mm and 7 mm, with an estimated remaining life of approximately 23 years from an initial crack length of 1 mm. A comparative shroud case produced a much lower crack driving force. Analytical validation using an edge cracked plate showed differences below 2%, indicating that the proposed framework is reliable at the analytical benchmark level.