Studies on Torsional Vibration of Rotary Tine Shaft

Abstract

Following analyses were carried out to clarify torsional vibration of rotary tine shaft during operation for sand: 1) computation of power spectral density (PSD) for tine shaft torque and XYZ-directional accelerations, 2) numerical analysis of natural frequency for utilizing Holzer's successive method. Several findings can be drawn as follows.
(1) In the case of deep tillage (around 10cm deep), the contained frequency components of tine shaft torque vary with inherent fluctuations at the higher frequency region. On the contrary, in the case of shallow tillage (5 to 6cm deep), the significant frequency region spreads with the increase of tine shaft speed.
(2) It is of interest to note that, in X-directional acceleration, only tine shaft speed affects to the PSD tendency in no-load condition. What is more, the number of tines play important roles to transfer the frequency component characteristics in shallow tillage.
(3) It is clearly evident that Y-directional acceleration shows dominant magnitude of PSD at 5 to 10f₀ in no-load condition.
(4) Any salient trends can not be discerned for Z-directional acceleration in no-load condition. This seems due to bouncing of the chassis.
(5) Using Holzer's successive method, it can be predictable that the thickness of rotary tine shaft and its mass distribution affect natural frequency of rotary tine shaft.