Asonye, Gladys Uche2026-03-232026-03-232021-07Asonye, G. U. (2021). Numerical and experimental studies of the energy requirements for cutting selected tuber crop tissue and vegetables [Unpublished Doctoral Thesis]. Federal University of Technology, Owerri, Nigeriahttps://repository.futo.edu.ng/handle/20.500.14562/2461This thesis is for the award of Doctor of Philosophy (Ph.D.) in Power and Machinery EngineeringNumerical and experimental studies of the cutting energy requirements for selected tuber crop tissue and vegetables was undertaken in this research work. Prediction models using dimensional analysis based on Buckingham pi theorem were developed for the cutting energy requirements for four selected crops which are indigenous to the area of study; tuber crop (cocoyam) (Colocasia esculenta), fruit vegetable (okra) (Abelmoschus esculentusL.), bulb vegetable (onion) (Allium cepa.) and fruit vegetable (garden egg) (Solanium marcrocarpon). The developed cutting energy prediction models using dimensional analysis based on Buckingham pi theorem for cocoyam (Colocasia esculenta), okra (Abelmoschus esculentus L.), onion (Allium cepa) and garden egg (Solanium marcrocarpon) were validated with experimentations. High coefficient of determination (R2 ) values of 0.98, 0.99, 0.98 and 0.98 respectively obtained for cutting energy values between the predicted and the measured values with the developed automated cutter showed that the mathematical models are good. The developed arduino-controlled automated cutter consists of two parts; the hardware and oftware components. The hardware is composed of an electronic windshield motor, four 25mm2 stainless steel pipes of 4cm height for supports, a 35cm x 29cm x 8mm stainless steel plate for the base, a 12cm stainless threaded shaft and 4 pieces of 5cm stainless angle irons. The software consists of Arduino microprocessors (Integrated Development Environment, IDE), load cells (sensors) and a Liquid Crystal Display (LCD). The arduino processor automatically and effectively measures, records and stores cutting variables (speed, force, displacement and time) with minimum human supervision. Connecting the cutter to an electrical power source switches on the electronic windshield motor, which causes a rotational motion of the shaft and a subsequent reciprocating motion of the knife holder. The cutting process which is a non-reversible system involves both compressive and shearing deformations. The operational process involves speed selection, movement of knife edge through product, exertion of reactive force on the load cell and computations. The reactive force exerted on the load cell is measured and automatically relayed to a computer via a Universal Serial Bus (USB) port for storage and further processing. Matrix Laboratory (MATLAB) which is a high performance language for technical computing intercepts the stored values and plots the resulting graph of force of cut against displacement which is used in calculating the energy of cut. Variables involved in the model development using dimensional analysis based on Buckingham pi theorem were; tool weight, distance of cut, tool edge thickness, cutting speed, varying crop sizes, crop moisture content, crop contact area and crop density. Lastly, optimization of the cutting process was carried out by studying the interactive effects of three variables on the energy requirement to cut the select crops. It involved experimentations using the Randomized Complete Block Design (RCBD) layout and observing the effect of the different combinations on cutting energy requirements. These variables are cutting speeds and knife edge angles at 5 levels of 20, 25, 30, 35 and 40mm/min and 200 , 270 , 340 , 410 and 480 respectively with equivalent crop sizes of 33.68, 41.02, 45.34, 50.31 and 64.89mm for cocoyam (Colocasia esculenta); 11.23, 13.28, 17.82, 20.52 and 24.47mm for okra (Abelmoschus esculentusL.); 42.84, 51.78, 61.36, 77.35 and 84.10mm for onion (Allium cepa.) and 25.69, 32.87, 40.31, 47.69 and 52.73mm for garden egg (Solanium marcrocarpon). The three variables were observed to have significant effects on the cutting energy requirements for the four crops studied. The optimization of the cutting process was observed to occur at equivalent diameter of 33.68mm, cutting speed of 35mm/min and knife edge angle of 200 for cocoyam;47.61mm, 35mm/min and 200 for onion bulbs; 23.80mm, 50mm/min and 200 for okra and 45.41mm, 35mm/min and 200 for garden egg fruit. All the optimized results were at the lowest knife edge angle of 200 and the 35mm/min cutting speed except okra which occurred at the cutting speed of 50mm/min. The optimization study helped in the determination of the best combination of the chosen factors that would lead to maximizing energy consumption during the cutting process of the understudied agricultural crops. The results of this study find usefulness in designing, analyzing and optimization of the cutting process for these select crops.enAttribution-NonCommercial-ShareAlike 4.0 InternationalCutting processenergy requirementmodelingbuckingham pi theoremtuber crop and vegetablesarduino processoroptimizationDepartment of Agricultural EngineeringDoctoral Thesis