Numerical Approach to Fatigue Life Prediction of Harrow Tines Considering Geometrical Variations

Harrow tine is a widely used tool for mechanical weeding. However, the effect of its geometry on its fatigue life is something that has not been studied well yet. In this work, two different harrow tines (0.5260” HT and 0.6253” HT) were analyzed to understand how their geometry affects their fatigue life under different field conditions and material properties. Finite element analyses were performed on these harrow tines by applying different degrees of leg deflections (3, 6, 8, 10, and 12 inches) for von Mises stress distributions and failure life cycles. The results suggested that 0.526” HT has a longer cycle life than 0.6253” HT. With the largest leg deflection and controlled conditions, 0.5260” HT exhibits a harrowing capability of 133.62 hectares, which is larger than 0.6253” HT’s 117.66 hectares. Apart from the numerical analyses, prototypes (1:0.35 scaled-down model) of these harrow tines were additively manufactured using a rigid ultraviolet curable resin. Finally, a custom test setup was used to perform simple load-bearing tests of these harrow tines.