Determination of coefficient of restitution of fresh market apples caused by fruit-to-fruit collisions with a sliding method

The coefficient of restitution (CoR) is one of the essential parameters required using nu-merical simulation to investigate materials' kinematics and collision mechanics. This study presented an approach with a sliding method for determining the CoR of apple-to -apple collisions. A platform was developed for performing fruit-to-fruit collisions (FFC) in the air, where pairs of fruit were slid together with sliders created by three-dimensional (3D) printing technology. The CoR involving rotational energy was determined using high-speed photography for different treatments of four collision velocities (0.8, 1.2, 1.6, and 2.0 m s-1), three collision angles (25, 35, and 45 degrees), and across three zones of the fruit (stem shoulder-to-cheek, cheek-to-cheek, and calyx shoulder-to-cheek). The statistical significance between mean values of studied quantities was determined by analysis of variance at a 5% significance level. Results indicated significant effects of collision velocity, collision angle, and their interactions on the CoR. The CoR decreased with increasing collision velocity irrespective of collision angles, but the decrease was smaller at the larger arc. The CoR significantly increased with increased collision angle only under higher speeds, and the increment was also more significant at higher velocities. The total bruise volume varied nonlinearly with increased CoR; thus, CoR could serve as a helpful indicator of the threshold level for fruit bruise damage. The CoR should be over 0.84 without bruise damage on fresh market apples. This methodology and results will help create a more accurate fruit model and thus design optimal apple production systems.(c) 2022 IAgrE. Published by Elsevier Ltd. All rights reserved.