FEM Analysis of Effects of Mechanical Impact Parameters on Fruit Characteristics

Abstract

Mechanical impact on fresh agriculture commodities may be a criterial issue during mechanical processes such as grading, sorting, conveying, packing or transport. The applications of electronic measuring devices in form of artificial fruits like ‘Instrumented Spheres’ (IS) are an aid to quantify influences of mechanical impact on the value of fruit, vegetable and potato. Additionally, modelling and simulation of impact on fruits helps to identify those influencing parameters. In this study, modelling and simulation runs were performed based on the Finite Element Method (FEM). For dropping tests an ‘Acceleration Measuring Unit’ (AMU) was used which can be implemented into real or artificial fruits to measure the accelerations upon impact. The test stand was equipped with a force sensor. The relevant parameters Young moduli, density, mass, fruit dimensions, and dropping test heights were varied for the tests. FEM simulation results were compared with measured acceleration values of the AMU and force values of the test stand. On dropping potato tubers with mass of 100‑120 g from 25 cm height onto steel plates, the impact force ranged from 190 to 220 N. Simulations showed that the impact force in similar conditions (mass of 102‑113 g and Young moduli of 2.5‑3.5 MPa) ranged from 198 to 242 N, which is in good agreement with the experimental results. When the tuber mass was 190‑210 g, the measured impact force varied from 310 to 325 N. Simulations for masses of 199–221 g resulted in impact forces of 306‑325 N, again in good agreement with the experimental results. However, AMU acceleration values ranged from 922‑932 m s^-2, for masses of 100‑200 g, to 765‑824 m s^-2 for masses of 190‑210 g. Simulations, in similar conditions, provided acceleration values of 1934‑2314 m s^-2 for masses of 102‑221 g (Young moduli 2.5‑3.5 MPa) and ranging from 1497 to 1843 m s^-2 for masses of 199‑221 g, which are about twice as high than measured, probably due to effects from imperfect fit when implanted the AMU into the test fruit.