Mechanical design and performance evaluation of ventilated packages

[摘要] ENGLISH ABSTRACT: Ventilated corrugated paperboard (VCP) packages are used extensively in the fruit industry to minimize damage and facilitate airflow around the produce to maintain the cold chain. In the postharvest journey of fruit, these packages are subjected to a multitude of dynamic and static forces such as impacts, compression and vibration which results in damage and reduces the quality of the packaged fruit. This thesis aims to develop a validated finite element analysis (FEA) model to assist in the mechanical design of VCP packages. Another aim is to evaluate the performance of apple fruit packaging by investigating the resistance of the packages to the forces they are subjected to during postharvest handling, and characterising the bruise susceptibility of the fruit inside the packages. A validated FEA model was used to study the effect of vent height, shape, orientation, number of vents and area on the strength of the packages.Results showed that incidence and susceptibility to bruise damage of the apple fruit was affected by package design when subjected to impact, compression and vibration loads. Bruise damage increased with an increase in drop height with a significant increase of about 50% when the package drop height increased from 30 cm to 50 cm. The bottom layer of the package was more susceptible to bruise damage when subjected to impact load. Under vibration load, the highest bruise damage was observed at a frequency of 12 Hz, where the greatest packaging transmissibility of 243% occurred. The top layers of the package were prone to bruise damage under vibration load. Compression strength of the packages reduced by about 16% when environmental condition was changed from standard condition (23℃ and 50% RH) to refrigerated condition (0℃ and 90% RH). Under compression load, irrespective of package design, the highest and lowest bruise incidence of bruise damage occurred at the top and bottom layers of the package, respectively.The incipient buckling load of the package obtained from the FEA model could accurately predict the experimental value obtained during the compression test. The difference between the numerical and experimental values was within 9%. Increasing the vent area from 2 to 7% reduced the buckling load with about 12%. Vent number, orientation, and shape affected the buckling load of the packages. Rectangular vent holes better retained the strength of the packages compared to circular vent holes. Vent height significantly reduced the buckling load of the packages. The results obtained from this research provided practical guidelines for improving future design of packages for the South African fruit industry.

[发布机构] Stellenbosch University