Status:Closed Asked:Jul 07, 2011 - 08:21 AM
Does the time my package was vibrated in the lab equate to distance traveled in shipment?
The answer to the question of whether a specific vibration test time requires to actual distance traveled in shipping is YES and NO, depending on the test and the shipping means. YES, under certain specific conditions. NO for many common packaged-product tests.
If the vibration test is (1) random vibration with a spectrum shape that is an accurate representation of the actual transport vibration, and (2) run for the same amount of time as the actual shipment, or time-compressed in accordance with an accepted formula, then vibration test time can be correlated to actual shipping time or distance.
If either condition (1) or (2) above is not met, then the vibration test cannot be reasonably and accurately correlated to shipping time and distance. This doesn't mean that the test isn't useful, only that there is not a strong relationship to actual transport.
All of the ISTA 1-Series "Non-Simulation Integrity Tests" are "not designed to simulate environmental occurences", and therefore there is no correlation, expressed or impled, between 1-Series vibration and actual shipping times or distances.
ISTA 2-Series tests are the same as the 1-Series with regard to their vibration sections, except for Procedure 2C. While 2C includes shaped random spectra reasonably representative of actual transport vibration, the test time is constant and rather arbitrary. THere has been no attempt at correlation to actual ship time/distance.
ISTA 3-Series "General Simulation Tests" offer the best correlations. Project 3B and Procedures 3E and 3H contain a formula relating to miles and kilometers to test time, so the correlation is clearly stated.
ISTA Project 4AB, available to members for no additional charge through the ISTA Member Center, includes test time vs. shipping time/distance correlations.
For a more complete discussion of this topic, download the paper written by WIlliam Kipp (presented at ISTACon in 2000, and revised/updated in 2008), which is available online. Click here for a PDF copy of the paper.
Source: ISTA Staff
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