Title of article :
Uninterrupted and accelerated vibrational fatigue testing with simultaneous monitoring of the natural frequency and damping
?esnik، نويسنده , , Martin and Slavi?، نويسنده , , Janko and Bolte?ar، نويسنده , , Miha، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2012
A mechanical systemʹs modal parameters change when fatigue loading is applied to the system. In order to perform an accelerated vibration-based fatigue test these changes must be taken into account in order to maintain constant-stress loading. This paper presents an improved accelerated fatigue-testing methodology based on the dynamic response of the test specimen to the harmonic excitation in the near-resonant area with simultaneous monitoring of the modal parameters. The measurements of the phase angle and the stress amplitude in the fatigue zone are used for the real-time adjustment of the excitation signal according to the changes in the specimenʹs modal parameters. The presented methodology ensures a constant load level throughout the fatigue process until the final failure occurs. With the proposed testing methodology it is possible to obtain a S-N point of the Woehler curve relatively quickly and to simultaneously monitor the changes of the specimenʹs natural frequency and damping loss factor. The presented methodology with real-time control is verified on an aluminum Y-shaped specimen (106 load cycles are achieved in 21 min) and is applicable to a specimen with arbitrary geometry. Besides the faster completion of the fatigue test the methodology can be adopted for the validation of the vibrational fatigue analysis.
Journal title :
Journal of Sound and Vibration