Finite Element Analysis of the Influence of Extrusion on the Stress and Strain of Lingwu Long Jujube

In order to analyze the response law of internal stress and strain to extrusion of Lingwu jujube during the picking process and provide theoretical basis for the design of picking robot, in the paper universal mechanical testing machine was used to compress the whole fruit horizontally and vertically under five different extrusion rates of 15, 20, 25, 30 and 35 mm/min, and then fit the force deformation curve. The stiffness and fracture force of jujube were obtained. The two lateral extrusion rates of 15 and 35 mm/min were simulated by finite element method, and the finite element model was established. The results showed that the mechanical properties of Lingwu jujube were anisotropic and the lateral compressive capacity was stronger when it was squeezed. Under transverse compression, the whole fruit fracture load was 214.34 ~ 266.53 N, the elastic modulus was 14.90~17.05 MPa and the relative deformation was 20.70%~22.67%. During longitudinal compression, the whole fruit fracture load was 132.52~185.40 N, the modulus of elasticity was 4.59~6.07 MPa, and the relative deformation was 13.72%~17.25%. The stress and strain of the stress point was the largest in pulp, and extended along the equator to the surrounding fruit core, and decreased gradually. The difference between the simulation value and the experimental value of the finite element model with compression rate of 15 mm/min was 14.98%, and the deviation of 35 mm/min was 11.06%. It was feasible to apply the finite element method to the simulation of Longwu jujube extrusion.