Marco Bentini

The use of an electronic beet to evaluate sugar beet damage at various forward speeds of a mechanical harvester

Mechanical harvesting strongly affects the quality of sugar beets, mainly in terms of root injuries, tare, and nextracted sugar. In Mediterranean countries, the effects of sugar beet damage are more critical because of the warm and nhumid climate at harvesting time. In order to investigate the dynamic interaction between mechanical tools and roots, nelectronic devices have been developed in some European countries for measuring impacts experienced by roots when passing nthrough the harvesters. At the University of Bologna, an electronic beet with a 4905 m/s 2 tri–axial accelerometer was ndeveloped in 1998. This device was used in a field trial for measuring and recording impacts in terms of peak acceleration, nduration, and velocity change during impact. The device was placed into the soil in place of a real beet and then harvested nby a six–row self–propelled harvester, which was tested at four different forward speeds. Assessments of the level of damage non the harvested sugar beets were also carried out according to the IIRB international method. The aim of the study was to nevaluate how different forward speeds tested on a single harvester can affect damage to the roots, to assess the damage caused nat each step of the harvesting process, and to find a correlation between damage and impacts. nMechanical parameters recorded by the electronic beet were referenced to three specific positions, defined as A, B, and nC zones, within the harvester. The ANOVA results in A zone, composed of lifting shares and roller bed, and in B zone, composed nof transfer web and turbines, showed a statistical significance. In C zone, composed of tank elevator and tank, the variables nhad no statistical significance. The results of the trial showed that A zone had the highest values of the variables. A harvester nforward speed of 6 km/h caused the fewest taproot breaks and bruises. A linear model describing the relationship between ntaproot breaks and impact velocity change showed a statistical significance for A zone, while no significance was determined nfor B zone.

MECHANICAL PROPERTIES OF SUGAR BEET ROOTS

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