Evaluation of impact effect and fruit properties on apple dynamic behavior

Apple fruit can be damaged because of some impact forces which are the main sources of apple degradation during the contact. To reduce the damage, it is necessary to investigate normal contact forces. The normal contact force models depend on dynamical parameters such as spring and damping. The spring and damping parameters of Kuwabara and Kano normal contact force model are obtained in different levels of impact velocity (0.1; 0.2; 0.27; 0.34; 0.5; and 0.7 m s) for apple fruit by using the nonlinear least squares method. Significant effects of impact velocity, contact time, fruit properties (effective radius of curvature and acoustic stiffness) and some interaction effects on spring and damping parameters were obtained at probability level of 5% with determination coefficient (R) of 0.98 and 0.94 for “k” and “c” models of Golden delicious and also 0.98 and 0.98 for Golden delicious, respectively. However, there was no significant acoustic stiffness effect on the “k” and “c” parameters. The results showed that lowering the impact velocity and increasing the effective radius of curvature and contact time will enhance the parameters “k” and “c” of the apple fruit.