The analysis of the reference shaft under torque measurement unit for turboshaft engines

Gas turbine engines have become a dominating and convincing power source in aviation; for instance, turboshaft gas turbine engines are widespread propulsion systems for helicopters. In turboshaft engines, produced power is transmitted to the helicopter rotor group via a power output shaft. The level of power extraction depends on the transmitted torque and rotational speed of the power output shaft. The need to measure the torque from a rotating shaft leads to the development of various torque measurement units. The commonly used torque measurement unit (TMU) of compact turboshaft engines makes use of an angular twist method. The angular twist method is a multidisciplinary approach with a strong base in mechanics, electronics, and control. In this thesis, a comparison of TMU of various turboshaft engines, which use the angular twist method, is done concerning mechanical discipline. The new generic conceptual design of the reference shaft is done under TMU to be used for different turboshaft engines with minor modifications. The reference shaft is analyzed in terms of strength and vibration criteria. Static structural analysis is done to examine the mechanical integrity of the reference shaft. X-ray diffraction method is used to measure the residual stresses on the reference shaft. Modal analysis is done for vibration characteristics, and it is validated via the impact hammer test. Finally, the measurement accuracy of the TMU and the need for calibration are discussed in future wor