Finite element analysis of the dynamic behaviour of table grapes during mechanical harvesting

Abstract

The finite element analysis method, combined with impact analysis, was used to study the dynamic behaviour of grape berries in the horizontal and vertical directions under excitation. It was shown that grapes exhibit various behaviour forms, such as the single-berry bouncing, squeezing two-berries jumping, squeezing three-berries shaking, squeezing four-berries swing and micro-swinging of grape in the first 30 modals. The grapes oscillated the most at approximately 14.45 Hz and 15.35 Hz. The fruit-stem system was extremely active under vertical impact, often showing jumping and rebounding phenomena, and occurring a certain degree of bending and twisting as well, while the berry under horizontal impact only showed the characteristics of shaking. Therefore, vertical impact is more likely to cause violent movements of berries than horizontal impact. Thus, the finite element analysis method can accurately simulate the dynamic behaviour of berries under extrusion, and can provide a theoretical basis for analysing postharvest damage of grapes.