Mechanical properties of sugar beet roots

In Italy, as in many Mediterranean countries, different harvesting techniques have been developed for sugar beet. In countries where the multi-stage harvesting of sugar beets is common practice, the roots are deposited on the ground in windrows. The results of previous research demonstrated that the roots, depending on their stay in the field after lifting, are subject to changes in the industrial values of the raw material because of sucrose losses and the formation of non-sugars. It is important to determine how this stay in the field might also change the mechanical properties of the roots, which will later interact with the loader's mechanical tools on a self-loading trailer. Laboratory tests were therefore done on sugar beets lifted at two harvesting dates. Quasi-static compression and dynamic tests were performed. A preliminary analysis showed that the sugar beet root was composed of homogeneous material for the purposes of determining Poisson's ratio. In the quasi-compression tests, the value of Poisson's ratio changed depending on the compression load, while the apparent modulus of elasticity was unaffected. The values of apparent modulus of elasticity were also unaffected by sugar beet harvesting date but changed with the length of time the roots remained in the field after harvesting, showing a higher deformability in roots that had been left just a few hours. In the dynamic tests, the mean values of impact velocity changed and duration increased from roots tested immediately after lifting to roots that remained in the field after harvest.