Investigation and design for HCF/LCF complex fatigue experiment method of fan shaft

In order to accomplish the fan shaft's high-cycle fatigue/low-cycle fatigue (HCF/LCF) complex fatigue experiment under combined loading of axial force, principal torsion, vibration torsion and rotating moment, the sample's boundary conditions was simulated truly without inducing other extra loading. A loading method under these conditions was proposed based on mechanism design skills, hydraulics kills and computer data acquisition technology, meanwhile four kinds of loading control and calibrated system were established, and a fan shaft fatigue experiment device of high bypass ratio turbofan engine was designed. Making use of computer measurement and control systems, this experiment device can achieve the harmonious loading of axial force, principal torsion, vibration torsion and rotating moment by signal extraction, electro-hydraulic servo valve and mechanism system. Result showed that the high circle loading frequency could reach to 9Hz, the precision of low circle fatigue, vibration torsion and 92.75% the rotating moment to be loaded was superior to than ±0.12%, ±2% and ±5%, respectively, the maximum error of rotating moment didnt exceed ±9%. This experiment device has well repeatability and linearity.