CAD-Based Structural Analysis and Finite Element Topology Optimisation of a Leaf Spring Bracket for a Light Commercial Vehicle

Abstract

Topology optimisation is a mathematically rigorous technique for redistributing material within a defined design domain to minimise structural compliance while satisfying prescribed mass and stress constraints. This paper presents a complete design–analysis–optimisation–fabrication–validation workflow applied to a leaf spring mounting bracket of a light commercial diesel truck. The bracket, fabricated from SS 4012A-E34 hot-rolled micro-alloyed structural steel, was originally characterised by a minimum factor of safety of 2.018 and a peak equivalent von Mises stress of 67.9 MPa under a service load of 6,000 N derived from the front axle loading of the vehicle. Three-dimensional parametric modelling was carried out in CREO Parametric 2.0, and both static and fatigue analyses were executed in ANSYS Workbench 19 using SOLID187 tetrahedral elements at a 2 mm global mesh size. Topology optimisation was subsequently performed with a compliance minimisation objective and an 80 percent mass retention constraint, followed by a shape optimisation study comparing square, circular, and triangular cut-out geometries for the vertical plate. The circular cut-out was selected on the basis of minimal corner stress concentration. The re-engineered optimised bracket incorporates a rectangular slot on the horizontal plate and a circular aperture on the vertical plate, reducing component mass by 200 grams (from 1.8 kg to 1.6 kg, an 11.1 percent reduction) while maintaining essentially unchanged peak stress (66.79 MPa versus 67.9 MPa) and preserving infinite fatigue life. Physical fabrication was accomplished through wire-cut electrical discharge machining, milling, and drilling operations. Experimental validation via strain gauge testing on a Universal Testing Machine (UTM) yielded 153.2 microstrain at 6,000 N, against an FEA prediction of 180.7 microstrain, representing a 15.2 percent discrepancy within the accepted tolerance for fabricated metallic components. The study confirms that topology optimisation within a conventional FEA environment provides a systematic and manufacturable pathway for mass reduction in automotive mounting hardware.