Blood orange clamping damage mechanism based on finite element method

To reduce the clamping damage caused by robotic manipulators during the harvesting of blood oranges, this study investigated the mechanical response of blood oranges when in contact with curved surfaces of different curvatures. A three-dimensional model of a blood orange was established using reverse engineering technology, and its physical properties were measured. A peel-pulp composite finite element model was constructed to simulate the uniaxial static compression test and the contact process of blood oranges clamped by curved surfaces of varying curvatures. The results indicated that the maximum error in the uniaxial static compression test was 6.8%, confirming the accuracy of the model. In the simulations of the curved surface clamping tests, the stress at the contact point between the blood orange and the curved surface was highest, with the pulp being damaged before the peel. A comparison of the effects of different curved surfaces on the stress and deformation of the blood orange revealed that, under the same clamping force, the 46 mm radius curved surface resulted in lower stress and smaller deformation in the various parts of the blood orange compared to the other curvatures. When a clamping force of 40 N was applied, the bruise volumes caused by the 44, 46, 48, and 50 mm radius curved surfaces were 3897.11, 1193.93, 10553.72, and 21889.74 mm³, respectively. Therefore, the 46 mm radius curved surface posed the lowest risk of mechanical damage to the blood orange. This study provides a reference for the micromechanical research of citrus fruits and offers a basis for the design of end-effector harvesting devices.