Iterative and Dynamic Analysis of 3d Crack Growth in Turboshaft Engines: A Focus on Blower Stiffness and Vibration

Abstract This study investigates the dynamic response of a gas turbine engine with a particular focus on the role of the blower in the turboshaft engine blower and its susceptibility to crack formation under high cycle fatigue (HCF). Through modal and harmonic analysis, mode shapes, vibration levels, and phase angles are assessed to find the impact of cyclic loading on the engine’s structural integrity. Both a finite element analysis (FEA) based and numerical approaches are utilized, incorporating a 3D crack growth algorithm that updates the blower’s geometry iteratively. This method captures key changes in area reduction, stiffness, frequency response, and stress states, along with corresponding shifts in vibration behavior as cracks propagate. The study uniquely models the blower’s response, highlighting its influence on overall engine structural performance and vulnerability to fatigue. By refining the iteration loop and accounting for evolving stiffness change in structure, the approach offers an improved framework for life cycle prediction. Iterative solution results are compared with non-iterative, fixed, stress state life cycle prediction and the consequence of stiffness change during crack growth is emphasized. The differences in the results are underlined and conclusions are drawn between the different techniques.