FEM explicit dynamics simulation and NIR hyperspectral reflectance imaging for determination of impact bruises of Lycium barbarum L.

Abstract

A 3D scanner was used to reverse engineer a model to assess impact bruising of fresh Goji (Lycium barbarum L.) fruit. Based on the results of physical compression tests, an elastic-plastic model was selected as the material mechanics model for the fruit. A finite element method explicit dynamics simulation was performed to predict impact bruising using Abaqus software. Simulation results showed that fruit were not damaged at a drop height of 0.2-0.5 m, an impact angle of 10–30 °, and with an impact material of wood board, foam board, and nylon board. Using response surface methodology, the effects of drop height, impact material, and impact angle on the bruise rate of fruit were determined. The optimized parameters were a drop height of 0.24 m, foam board as the impact material, and an impact angle of 13.11°. Near infrared hyperspectral reflectance imaging was also applied to this problem, and visualization models were established in Matlab. The field experiment showed a bruise rate was 9.8%. These results provide a theoretical basis for future studies of harvesting, transporting, sorting, grading, and packaging machines designed for use with L. barbarum.