Design, Response Surface Optimization, and Evaluation of a Four-Wheel Tractor Peanut Digger

Peanut harvesting remains labor-intensive and costly due to the limited availability of locally developed mechanized harvesting technologies. Thus, this study presents the design, optimization, and evaluation of a four-wheel tractor peanut digger to advance harvesting. Structural integrity was evaluated using Finite Element Analysis (FEA) in ANSYS under a draft load of 2008.2 N, yielding a maximum von Mises stress of 33.012 MPa, a peak strain of 0.00015, a maximum deformation of 1.72 mm, and a factor of safety of 5.74, confirming adequate structural reliability. Field performance was optimized using a Box–Behnken Design (BBD) with tractor speed, digger blade lift angle, and clearance angle as factors, while material capacity and digging efficiency served as response variables. Regression analysis showed that the main effects significantly influenced both responses, whereas interaction effects were insignificant. Response Surface Methodology (RSM) optimization identified optimal operating conditions of a 14.95° lift angle, 15.70° clearance angle, and 1.74 km·h−1 forward speed, achieving a predicted material capacity of 0.56 t·h−1 and digging efficiency of 96.69%. Validation tests improved these values to 0.59 t·h−1 and 97.42%, demonstrating that integrating numerical methods provides an effective approach for developing adoptable and structurally reliable peanut harvesting machinery.