Vibration of Fresh Fruits and Vegetables During Refrigerated Truck Transport
Summary:
In transportation tests with fresh fruits and vegetables, refrigerated trailers equipped with steel - spring suspension systems had highest Power Spectral Density levels at about 3.5 Hz. Other frequencies with high PSD levels were 9, 18, and 25. However, in trailers equipped with an air-ride suspension system, the PSD levels were attenuated at 3.5 Hz and reduced at other frequencies. The highest PSD levels were found at the rear of the trailer, with resonance occurring in the loaded boxes at some frequencies.
Horizontal acceleration was much less than the vertical acceleration. The results may show the less damaging suspension type of produce transport, how to improve either suspension type, or what packaging systems should be designed.
Abstract:
Fresh fruits and vegetables experience losses in the marketplace that are caused by mechanical injuries. Past studies have indicated that transit vibration contributes to this loss, and may be more important than impacts as a source of damage. In cross-country tests of cherries, nectarines, and pears in semi-trailers equipped with steel-spring suspension systems, highest Power Spectral Density (PSD) levels were found at about 3.5 Hz.
In this study, PSD is used to mean acceleration spectral density. Other frequencies with high PSD levels were 9, 18, and 25 Hz. Similar results were found in tests with fresh tomatoes. However, in trailers equipped with an air-ride suspension and loaded with tomatoes, the PSD levels were attenuated at 3.5 Hz., and were reduced at other frequencies. The highest PSD levels were found at the rear of the trailer, with resonance in the loaded boxes occurring at some frequencies. Horizontal acceleration was much less than the vertical acceleration.
Understanding acceleration levels and frequencies that occur during shipment of perishables in refrigerated trailers will help to determine methods that will dampen the vibration energy and reduce the present losses in produce quality.