Discrete element method simulation of rice grains impact fracture characteristics

Abstract

The fracture of rice grains and other cereals is a common phenomenon during various processes such as seeding, harvesting, and processing. With the objective of elucidating the underlying fracture mechanisms involved, this paper aimed at simulating the fracture of rice grain caused by impacts at different locations on the surface using the discrete element method (DEM) and a bonded particle model (BPM). The aim was to establish an accurate BPM of rice grain using an impact bench test combined with the DEM. To uncover the mechanisms underlying the fracture of rice grains, the fracture process of rice grains at different locations was visualised using impact simulation. The findings demonstrated that this BPM can replicate the fracture behaviour of rice grains. The impact fracture velocity of rice grains varied across different locations, with the highest fracture velocity observed at the centre of the grain, reaching a maximum of 39.5 m s−1. The propagation of cracks played a crucial role in the occurrence of fractures in rice grains. The impact force and kinetic energy were concentrated in the impact zone, resulting in the formation of fracture surfaces in rice grains. The impact toughness of the impact zone in rice grains exhibited a direct correlation with the impact fracture velocity of the rice grains. This study elucidated the fracture mechanism of rice grains and determined the impact fracture velocities at different locations, thereby establishing a reliable foundation for minimising losses in various agricultural stages including seeding, harvesting, and processing.