Stress and fatigue analysis of the hydraulic motor shaft and conveyor joints of a tractor-mounted Chinese cabbage collector

Abstract

Deflection and fatigue damage in a tractor-mounted Chinese cabbage collector might occur due to continuous operation. Therefore, the objective of this study is to predict the service life of the material used for the hydraulic motor shaft and conveyor joints based on stress and fatigue analysis. The torque produced by the motor was measured using the torque sensor for various tractor forward speeds and rotational speeds under unloaded and loaded conditions with three iterations. The relevant shear stress with the S – N curve on fatigue life was determined using the Smith – Watson – Topper equation and rain flow cycle counting method. Additionally, the severity level was investigated using Miner’s rule. Design variables of the shaft diameter and conveyor’s joints were incrementally increased by 0.02 m. The experimental results of deflection and shear stress of the components were found to be negligible. The result of fatigue lifecycles was also generated over 107. The maximum severity level of the motor shaft, conveyor joints 1 and 2 were 4.27 and 4.48, 4.26 and 5.58, and 4.12 and 4.46, respectively under unloaded and loaded conditions. When the values of design variable components were increased incrementally, shear stress and deflection decreased gradually but the fatigue life increased. Nevertheless, the results indicated that this machine could be safely used in the field.