In recent years there has been a very significant increase in parcel delivery shipments all over the world. Moreover, this mode of delivery, in some cases, is facing a very intensive flow of goods, such as in annual festive seasons or, for instance, in situations like COVID-19 when personal purchase of goods is strictly limited in malls. This often means that delivery vehicles operate at almost full capacity, and many same or different kinds of packages are therefore stacked in small delivery vehicles. In this study, we measured and analyzed the vibration levels that occur in smaller stacks of packages in parcel delivery shipments, paying particular attention to those circumstances such as stacking layers and free movement spaces that can affect the vibration in different layers of packages. The goal of this paper was to provide information about the vibration levels that occur in smaller stacks of packages that are not unitized and fixed, as is common in parcel transportation. The recorded vibration events were analyzed in terms of power spectral densities (PSDs) and supplied with statistical data of acceleration events to provide an understanding of the variability of intensity. Based on the results of this study, PSD spectra were developed for various free movement conditions, as well as spectra for each layer in the stacked parcel package shipment. The results showed that the vibration level increases in the stacked load upwards and with an increase of free space of possible movement. The results of this study can be used to simulate the measured vibration conditions in laboratory tests conducted on courier express parcel shipments.
In the last decade, there has been a significant increase in parcel delivery shipments all over the world due to online stores and consumer demand to receive the products in a shorter period of time. It is especially true when situations like COVID-19 limits personal purchases in shopping malls as well as grocery and pharmaceutical stores. This often means that courier operators try to deliver packages utilizing vehicles with racks or shelves, which during the COVID-19 epidemic are not there anymore. This study measured the vertical vibration levels that occur in stacked parcels during express delivery versus the simulation technique in the laboratory. The goal of this paper was to measure and compare the vibration levels between laboratory practice and field transportation. For the measurement a three-layer stacked unit was built to observe the vibration levels on different road conditions in a parcel delivery vehicle and ASTM vibration profile (ASTM International). Then the measured acceleration-time data were analyzed in terms of power spectral densities (PSD) and the presented statistical data provided an understanding of the variability of intensity in different levels in stacked unit. The results showed that the vibration level increases in the stacked load upwards and with worse road conditions, but even in the worst case it did not reach those vibration levels that the laboratory test showed. Moreover, the layers of the stacked unit are in out-of-phase motion in the field, while the stacked unit in the vibration simulation usually is in-phase motion. Results indicate that the proposed vibration simulation does not correlate well with typical field vibration. This is fundamentally true as during a forced vibration created by a single-axis shaker, do not account for additional inputs occurring simultaneously creating an off-balance to the loads and as a result are less severe than simulated conditions. These findings are limited to single axis vibration simulation and unsecured loads.
In recent years, the volume of parcel shipments has increased significantly because of the rise in popularity of online shopping. This article focuses on the last mile segment of the parcel shipment, especially on the vibration behavior of the packages and van platform during transportation and the laboratory simulation of transportation vibration circumstances. The goal of this study is to measure in the field the vibration levels of small, stacked parcels and compare the results with measured vibration levels from the same measuring setup in the laboratory using ASTM D7386-16, Standard Practice for Performance Testing of Packages for Single Parcel Delivery Systems, vibration test method. For the measurements, three-layers of stacked small boxes with data recorder were set up into a delivery van to observe the vibration levels for the boxes inside and on the platform of the van, along different road conditions. The power spectral density spectra and overall Grms values of vibration intensity were presented and compared in four sections of frequency range between 1–200 Hz. The results indicate that the proposed vibration simulation does not correlate well with typical field vibration levels of the van platform and stacked packages. Based on the results, the packaging testing process can be developed as a more realistic preshipment testing process to avoid under-testing or over-testing of small parcels, thereby eliminating unnecessary packaging costs or damages.
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