Stress Analysis of a Welded Steel Bicycle Frame Using Finite Element Method

The structural reliability of bicycle frames manufactured by local welding workshops in Nigeria is rarely subjected to formal engineering analysis, raising concerns about rider safety and product quality in a market increasingly served by artisan fabricators. This study applies finite element analysis to evaluate the stress distribution and structural integrity of a welded steel bicycle frame representative of designs commonly produced in fabrication workshops in Aba, Abia State. A three-dimensional solid model of the frame was developed using SolidWorks software based on field measurements of a typical locally welded frame, and the model was imported into ANSYS Workbench for static structural analysis. Load cases corresponding to a 90-kilogram rider under pedalling, braking, and cornering scenarios were applied at appropriate boundary conditions. Von Mises stress distributions were mapped across all frame members, and critical stress concentration zones were identified at weld joints and at the bottom bracket shell. Maximum von Mises stress was recorded at 187 MPa, occurring at the chainstay-to-bottom bracket weld, below the yield strength of the mild steel material used. Deflection under maximum load was 3.2 mm at the seat tube, within acceptable limits for rigid frame designs. The study identifies three weld joint geometries requiring reinforcement and recommends specific bead profile improvements to reduce stress concentration factors. Keywords: finite element analysis, bicycle frame, stress analysis, welded joints, structural integrity.