Status:Closed Asked:Jul 06, 2011 - 11:34 AM
What is the difference between Procedures 1A/1B and 1G/1H?
ISTA Procedures 1G and 1H are essentially identical to ISTA Procedures 1A and 1B except for the vibration requirements. 1A and 1B require fixed displacement vibration (1 inch, 22mm, peak-to-peak), while 1G and 1H require random vibration at 1.15 Grms.
While it's generally recognized that random vibraiton in the laboratory can be the best way to simulate actual transport vibration, remember that the ISTA 1-Series tests "challenge the strength and robustness of the product and package combination" and are "not designed to simulate environmental occurances". So the random vibration in 1G and 1H is not shaped to match transport vibration and the overall intensity is much higher. It is designed to "challenge the strength and robustness", not to simulate.
These two approaches are alternatives, not equivalents, and will not necessarily produce the same results.
A number of users ave reported a preference for 1G and 1H over 1A and 1B. if you have appropriate equipment capabilities, you are encouraged to try both approaches to determine which might be the most suitable and effective in your particular situation.
Source: ISTA Staff
In addition to ISTA's answer, I would like to add a comment on why I prefer random vibration (1G/1H) over fixed displacement (1A/1B). Random vibration is a more repeatable test as the breakpoints that you plug into your control are definite. Fixed displacement tests require more judgment on what frequency causes the sample to "bounce". In testing, the more control over variability, the better.
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