Finite Element-Based Stress Analysis of the Main Frame of a Battery-Operated Lathyrus Harvester

Lathyrus (Lathyrus sativus L.) is a climate-resilient pulse grown mainly as a relay crop in rice fallows, but it is still harvested by hand, a slow, labour-intensive and physically demanding process. A battery-operated lathyrus harvester was therefore developed, and this study evaluated the structural safety of its main frame, the principal load-bearing component, using finite element analysis (FEA). A three-dimensional model of the frame was analysed in ANSYS Workbench 2024 R1 under static loads representing field operation, namely the weight of the battery, motor and transmission, the cutting resistance of lathyrus stems and the inertial force of the reciprocating knife. Structural steel properties were assigned, and support reactions, equivalent elastic strain, directional deformation and von Mises stress were evaluated. The maximum von Mises stress was 223.92 MPa, confined to a critical joint region and below the 250 MPa yield strength of the material, giving a minimum factor of safety of 1.12. The maximum equivalent elastic strain was 0.0011939 m/m and was limited to local stress-concentration zones, while most of the frame showed negligible strain. The frame deflected like a cantilever, with a maximum upward displacement of 11.995 mm at the free end and a maximum downward displacement of 8.913 mm near the restrained region. The frame is therefore safe against yielding under static field loads, but the narrow safety margin and the free-end deflection show that local reinforcement is needed to resist dynamic loads and keep the cutter bar aligned. The study demonstrates that FEA is an effective, low-cost tool for designing lightweight battery-operated harvesters for small farms.