| Summary: | This paper presents a finite element analysis of failure at the first stage (L-1) blade in a low-pressure 220 MW steam turbine. A crack was found at the leading edge vane of the fourth stage of some blades. The crack existed almost at the same position at several L-1 blades. Steam flows through the stationary blade and then pushes the moving blade, making the rotor rotates at high speed. The steam pushes a rotating blade by fluctuating pressure depending on the blade number and rotating speed. The effect of steam dynamics pressure on a blade's harmonics response and harmonics stress is investigated by finite element analysis using MSC Patran/Nastran 2019. Blade analysis was realized together with verification of the contact model between the blades. Two rotating blades are connected using a fixed round pin at the outer diameter of the blades. The result shows that when the pin contact model between the blades is bonded, the maximum dynamics stress works at the root blade caused by flexural elastic motion. Otherwise, when pin contact is touching or having looseness, the maximum stress occurs at the leading edge vane of the blade due to the torsional elastic mode. © 2023 American Institute of Physics Inc.. All rights reserved.
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