Effect of Prong-Base Filleting on Hoop Stress and Stress Concentration in a Single-Prong Jewellery Ring Using Finite Element Analysis

A prong-ring joint is a common structural problem in jewellery rings, where a sudden change in geometry may increase stress concentration in the area and lead to subsequent service failure or deformation. The influence of prong-base fillet radius on hoop stress concentration in a single-prong jewellery ring was investigated using finite element analysis. Four configurations with fillet radii of 0 mm, 0.25 mm, 0.50 mm, and 1.00 mm were evaluated under consistent material properties, meshing strategy, boundary conditions, and a 10 N radial loading condition. Hoop stress was extracted using a cylindrical coordinate system, and the Hoop Stress Concentration Factor was calculated using a common nominal reference stress. The unfilleted configuration exhibited the highest Hoop Stress Concentration Factor of 4.320. Introducing fillets of 0.25 mm, 0.50 mm, and 1.00 mm reduced the Hoop Stress Concentration Factor by 39.2%, 52.0%, and 62.4%, respectively, with the largest fillet producing the lowest factor of 1.624. The results demonstrate that increasing the prong-base fillet radius progressively reduces localized hoop stress concentration while the critical stress region remains at the prong–ring junction. These findings highlight the importance of geometric refinement in improving the structural stress distribution of single-prong jewellery rings.