Dynamic Analysis of Fatigue Life Prediction on the Shafts of a Modern Cassava Peeling Machine for Safe and Economic Use

Abstract

The durability of a machine structure is based on its mechanical performance through its entire service life. To avoid structural failures in machines, it is a standard design practice that machines be analyzed based on the types of loading (static and fatigue) associated with it in order to design safe and dependable machine structures. These types of analyses are performed with the purpose of estimating the behavior of the mechanical parts under specific operational conditions. The aim of this research is to investigate the effect of different loading to the maximum load on the redesigned shafts of an existing cassava peeling machine capable of peeling at least one (10) tons of   cassava tubers with different weight, size or shape per day  to ascertain the effects on the bending moment, shear force, deflection angle, shear stress and bending stress, and evaluate if there is need to reduce or increase the thickness of the shafts to a standard considered to be safe and economical. The three shafts of the cassava peeling machine have been carefully analyzed to check for their fatigue life under different loading conditions. From the analysis, with stress values of 48.640MPa, 49.1289MPa, 3.06089MPa and shaft diameter values of 34.6799mm, 34.7955mm, 13.7941mm evaluated from the reduced stress diagrams and ideal diameter diagrams for abrasive cylinder shaft, peeling cylinder shaft, and retainer shaft respectively, gave positive results because none of stress values were greater than reduced stresses (calculated stress value from Tresca’s theory) on the respective shafts. Therefore, a standard steel shaft of 35mm diameter is appropriate for manufacturing of the machine and also safe and economical.