Topological Optimisation of Agricultural Machine Frame Structures for Nigerian Manufacturing Constraints

This study applies topological optimisation methods to the design of agricultural machine frame structures, specifically generating structurally efficient designs that are manufacturable within the material and fabrication capability constraints of Nigeria's agricultural engineering industry. Agricultural machines manufactured in Nigeria frequently use overdesigned, inefficient frame structures that add unnecessary weight, increase material cost, and reduce fuel efficiency, partly because design optimisation tools are not routinely available to Nigerian agricultural machinery fabricators. Topological optimisation, which mathematically determines the optimal material distribution within a design domain for specified loading and boundary conditions, offers a route to more efficient structural designs. This study formulates and solves topological optimisation problems for the frame structures of three representative Nigerian-manufactured agricultural machines: a cassava processing unit, a grain thresher, and a tractor-mounted ridger. Multi-load case structural optimisation is conducted using SIMP density method in ABAQUS finite element software. Manufacturability constraints are incorporated through feature size control, symmetry constraints, and minimum member dimension requirements consistent with Nigerian workshop fabrication capabilities. Optimised designs are fabricated as prototypes and structural performance is validated through load testing against original unoptimised designs. Findings reveal that topologically optimised frames achieve equivalent structural performance with 22 to 35 percent material mass reduction depending on machine type. Fatigue life is improved in all optimised designs due to more uniform stress distribution. The study contributes an original topological optimisation methodology for Nigerian agricultural machine design and recommends design optimisation tools integration into Nigerian agricultural engineering training curricula.

Keywords: topological optimisation, machine frame design, agricultural machinery, Nigeria, structural engineering.