Research On Mechanical Damage Mechanisms Of Processing Tomato At Different Loads

In this paper, the study object was processing tomato the characteristic fruit in Xinjiang. First, pressuresituation during harvest, storage and transport was simulation by flatbed compression. Contact pressure wasmeasured by pressure-sensitive film in different maturity and loaded positions of processing tomato underdifferent load, The contact stress area was simulated by FEA. Compared FEA simulated withpressure-sensitive film measured result can reveal the laws of damage and provide a design tool forreducing the likelihood of processing tomato bruising occurring. The main contributions are as follows:（1）Contact pressure characteristics were gotten by pressure-sensitive film of processing tomato. Thered stress area is larger loaded higher pressure of the green ripe tomato (＞0.2MPa), the green area contactstress formed mainly when the maturity after turning stage (≤0.2MPa). contact stress formed mainly in therange of≤0.3MPa when the maturity after turning stage loaded at locule position. Contact stress in≤0.2MPa are higher than the range of0.2-0.3MPa when ripening from green to red ripe stage under differentload. Contact stress formed mainly in the range of0.2-0.3MPa when loaded at radial wall position of thegreen stage tomato. Contact stress between loaded at locule and radial wall position of the two-locule in thesame maturity, This indicate that the carrying capacity of three-locular slightly better than two-locularloaded at locule position, but worse than loaded at radial wall position. The mean stress showing a growthtrend with force increased and the largest when loaded at locule position, followed by three-locule. thecontact stress is smaller than damage area, the correlation coefficient R2were above0.8when fit contactstress and damage area, predict damage area more accurately use general stress area.（2）Contact pressure characteristics of processing tomato was gotten by simulated of FEA. Themaximum contact stress deviation from the contact center, the maximum contact stress distribute on bothsides of the radial wall position, the maximum stress at locule is slightly larger than at radial wall. Contactstress of three-locule is similar to two-locule when loaded at locule. The maximum contact stress ofthree-locule processing tomato is between loaded at radial wall and locule of two-locule tomato.（3）Internal stress distributions of processing tomato were studied at different loads when compressedat locular and radial wall using FEA. The results show that maximum stresses in mesocarp and locular gelof three-locular increase linearly while the stresses in exocarp increase exponentially with the increasingload. The tendency of the stresses in the portions of exocarp, mesocarp and locular gel of two-locular issimilar to three-locule processing tomato when compressed at locular. Morever, the equivalent stress in theradial wall tissue is slightly smaller than three-locular. The maximum stresses in exocarp and mesocarpincrease linearly with load increased when two-locular was compressed at radial wall, the stress in loculargel did not change obviously, two-locular processing tomato have slightly higher compression capabilitywhen compress at radial wall.