Advanced Biomechanical Modelling of Crop Harvesting Mechanisms for Developing High-Efficiency Harvesters for Nigerian Crop Varieties

This study develops advanced biomechanical models of the interaction between harvesting mechanisms and the structural properties of major Nigerian crop varieties, providing a theoretical foundation for designing high-efficiency crop harvesters optimised for local variety characteristics. Mechanised harvesting of cassava, yam, cowpea, and sorghum remains severely limited in Nigeria partly because available harvesting machinery was designed for foreign crop varieties with different mechanical properties. Developing effective harvesting machinery for Nigerian crops requires detailed understanding of the biomechanical properties of crop tissues, crop-soil interface behaviour, and the dynamic interactions between mechanical harvesting elements and crop structures. This study conducts systematic mechanical property characterisation of five varieties each of cassava, yam, cowpea, and sorghum commonly grown in Nigeria, measuring tensile strength, shear strength, bending modulus, and friction coefficients for relevant crop tissue interfaces. Discrete element method simulations model the dynamic interaction between harvesting mechanisms including digging blades, separation conveyors, and threshing cylinders and crop materials. Optimisation of mechanism geometry, operating speed, and material properties is conducted using the calibrated DEM models. Prototype mechanisms are fabricated and field-tested against the model predictions at Federal University of Agriculture Abeokuta and University of Maiduguri research farms. Findings demonstrate that current harvesting mechanism designs for Nigerian cassava operate at 35 to 55 percent of theoretical efficiency due to crop variety mechanical property mismatches. DEM-optimised designs achieve harvesting efficiencies 28 to 44 percent higher than existing designs. The study contributes an original biomechanical harvesting design methodology for Nigerian crops.

Keywords: biomechanical modelling, crop harvesting, discrete element method, Nigerian varieties, agricultural machinery.