Monitoring A Shipment Using the X16-1C
The GCDC X16-1C or MEL-x data logger products can record the movements of a package during shipment and record with precise time when an impact occurred. Time stamped g-force data can verify that critical freight was properly handled during shipment. The X16-1C is small and well-suited to small packages shipped in short transit times. The longterm logging capability of the MEL-x is applicable to freight shipments, such as domestic truck shipments or overseas freight containers.
Listed below are events regarding a crate shipped from Gulfport, MS to Port Edwards, WI. The crate was made of wood and measured approximately 36" wide, 48" tall, and 4" thick and the contents and crate weighed about 50 pounds total (22Kg). An X16-1C logger was mounted inside the crate against the wood using 3M Command adhesive strips. The logger was configured to sample and record constantly at 25Hz (no deadband or dwell settings).
The shipment used ground trucking services and took 2 days 18 hours to reach the destination. The data plots illustrate the progress of the crate and several significant impacts during handling. The plots also indicate when the crate was staged in the distribution center (no motion) and when it was transported in a truck (consistent vibration detected). Total time spent on the road was approximately 25 hrs 40 minutes.
|Tracking Status Provided by the Shipping Service|
|Gulfport, MS, United States||07/23/2013||5:18 P.M.||Delivered crate to depot|
|Gulfport, MS, United States||07/23/2013||6:28 P.M.||Origin Scan|
|Gulfport, MS, United States||07/23/2013||8:00 P.M.||Departure Scan|
|Jackson, MS, United States||07/23/2013||11:12 P.M.||Arrival Scan|
|Jackson, MS, United States||07/24/2013||4:37 A.M.||Departure Scan|
|Earth City, MO, United States||07/24/2013||1:43 P.M.||Arrival Scan|
|Earth City, MO, United States||07/24/2013||8:29 P.M.||Forwarded to the facility in the destination city.|
|Oak Creek, WI, United States||07/25/2013||2:30 P.M.||Forwarded to the facility in the destination city.|
|Oak Creek, WI, United States||07/25/2013||10:17 P.M.||Departure Scan|
|Stevens Point, WI, United States||07/26/2013||2:24 A.M.||Arrival Scan|
|Stevens Point, WI, United States||07/26/2013||5:27 A.M.||Out For Delivery|
|Stevens Point, WI, United States||07/26/2013||10:43 A.M.||Delivered|
The crate was subjected to at least 4 impact events over 5 g's. One particular event occurred at the distribution center located at Earth City, MO (the plot below is a taken from the "G" status listed above). The crate was flipped over and dropped on the opposite face. The impact peaked at 5.5g. The smooth transition of Ax and Ay (red and blue lines) indicates a free-fall condition.
|Crate is face down, possibly moving on conveyor system|
|The crate is being moved to the vertical position|
|The crate starts vertical (Az=0) and then is allowed to fall flat and hit face up (opposite side from start).|
|The rotation from vertical to flat takes about 0.5 seconds and the impact causes at least 5.5g of acceleration.|
|The crate is now facing upwards and is stationary.|
In this test case, the X16-1C logger was configured to sample at 25Hz. This means each sample is separated by 0.040 seconds. The impact events detected during shipment were captured by a only 4 to 6 data points, which is 160 to 240 milliseconds total for an event. A slower sample rate would likely miss the impact event. Sampling faster would provide better data fidelity and more accurate peak accelerations. However, sample rate greatly affects the power useage of the data logger. Selecting a suitable sample rate is a trade-off between data fidelity, logger operation time, and the amount of data accumulated. A sample rate of 25Hz was a reasonable compromise for monitoring this 50 pound wooden crate.