Modeling and simulation of belt bucket elevator head shaft for safe life operation

Abstract

This research paper presents a step by step conceptual design and life prediction approach for the design, modeling and simulation of head shaft of a belt bucket elevator, to be used for conveying grains to a height of 33.5 m and at the rate of 200 tons/h. output. For this elevator system, the force and torque acting on the head shaft as well as the bending moment were calculated. Furthermore, the diameter of each cross section of the shaft was determined taking into consideration the geometric and fatigue stress concentration factors, due to shoulders which contribute significantly to most fatigue failures of shafts. The stress induced on the shaft by the force and the factor of safety for each cross section of the shaft was calculated using the DE-Goodman criterion. The model of the shaft was created from the calculated diameters and subjected to static and fatigue analysis using SolidWorks FEA. The results were validated by comparing the values from the FEA and the calculated values for stress and factor of safety of the critical section of the shaft, which showed an equivalent value. The FEA gave a fatigue load factor greater than one, which signifies that the shaft will not go into failure mode within the infinite life cycle of the shaft. The value of the fatigue strength obtained from FEA was higher than the value for the maximum von misses stress of the shaft, this result shows that the head shaft will sustain the loading stresses over a finite life prediction. This research is significant because the stress induced forces on the head shaft from each component of the elevator system were properly identified and analyzed so as to obtain precise results for life prediction.