Despite numerous advancements in fruits packaging and handling, still a high percentage of these biomaterials are world widely handled in bulk, using a variety of boxes. As an example, the loss of tomato handling with such boxes in Iran is estimated about 25-35%. In this study the so-called Discrete Element Method (DEM) was employed to investigate and analyze the force distribution at the bottom of these handling boxes. The main objective of this study was to study the effect of box aspect ratio, particle shape and coefficient of friction between paticle-particle and wall-particle on the quality and quantity of force distribution pattern at the bottom of box and optimize the dimensions of these fruit handling boxes. Simulations were performed using some particles, corresponding to the number of fruits in a real box exists in the market. The spherical and non-spherical model particles were generated employing Multi-sphere method (MSM) (using two identical, overlapped spheres). Both spherical and non-spherical objects were considered (4 set of particles shape: One sphere, two sphere by 95%, 50%, 5% overlapping) and deposited into the simulated boxes, with different dimensions (aspect ratios: 1.1, 1.9, 2.7, 4.8 and 5.6) with 4 fiffrente coef.of friction (0.1, 0.5, 1.0, 1.5). In each set of simulations the amount and location of contact forces between particles and bottom of box were extracted from the model. This provided the force distribution at the bottom of box. The force analysis was performed using several criteria including, maximum, average and standard deviation of contact forces and prosity of fruit bulk. Simulation results for spherical particles in boxes with aspect ratio ranged from 7.6 to 1.07 showed that the pattern of contact force distribution at the bottom of box is not affected by shape characteristics of boxes. It was observed that the handling box with aspect ratio equal to 3.4 was the best dimension in terms of contact forces distribution and their deviation. The linear regression for standard deviation results shows that by increasing the aspect ratio, the distribution of contact forces at the bottom of handling boxes is moderately enhanced as the trend line of the standard deviation of contact forces is declining. This implies that by increasing the aspect ratio of boxes the contact forces become more uniform.

Keywords