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It is usually a laboratory test involving a special machine, a compression tester, to apply controlled compression on a test [[Laboratory specimen|specimen]]. A [[universal testing machine]] is sometimes configured to perform a package compression test. Compression testing can also involve a superimposed ''dead load'' to a test package.
[[File:Army.mil-2007-02-07-153623.jpg|thumb|150 px|Compression test for steel drum]]
==Test
A common method of conducting the test, as described in several published standard [[test method]]s, is to compress a box at a constant rate of 1/2 inch (12.5 mm) per minute between two rigid platens. The platens can be fixed so that they remain parallel or one can be pivoted or "floating". The test can be conducted on empty or filled boxes, with or without a box closure. Conditioning to standard temperature and humidity is important.
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As with any laboratory testing field [[Verification and Validation|validation]] is necessary to determine suitability.
==Corrugated
Corrugated shipping containers are exposed to compression hazards during storage and shipment. Proper compression strength is a key performance factor.
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Corrugated fiberboard can be evaluated by many material test methods including an [[Edge crush test|Edge Crush Test]] (ECT). There have been efforts to estimate the peak compression strength of a box (usually empty, regular singelwall slotted containers, top-to-bottom) based on various board properties. Some have involved [[finite element analysis]].<ref>{{cite journal |last=Urbanik|first=T J|authorlink= |date=July 1981 |title=Effect of paperboard stress strain characteristics on strength of singlewall corrugated boxes|journal=US Forest Products Laboratory Report|volume=401 |issue= |series=FPL|pages= |id=|url= |accessdate= |quote= }}</ref> One of the commonly referenced [[empirical]] estimations was published by [[Edge crush test|McKee]] in 1963.<ref>{{cite journal |last=McKee|first=R C|authorlink= |author2=Gander, Wachuta |date=August 1963 |title=Compression strength formula for corrugated boxes|journal=Paperboard Packaging |volume=48 |issue=8 |pages= |id=|url= |accessdate= |quote= }}</ref> This used the board ECT, the MD and CD flexural stiffness, the box perimeter, and the box depth. Simplifications have used a formula involving the board ECT, the board thickness, and the box perimeter. Most estimations do not relate well to other box orientations, box styles, or to filled boxes. [[Physical test]]ing of filled and closed boxes remains necessary.
===Calculating
Fiber Box Association have a method for calculating the required compression losses which includes the following factors:
* Time
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* Handling
==Dynamic
Containers can be subjected to compression forces that involve distribution dynamics. For example, a package may be impacted by an object being dropped onto it (vertical load)[https://www.youtube.com/watch?v=Y0AZBOiah2A] or impacted by freight sliding into it (horizontal load). Vehicle vibration can involve a stack of containers and create dynamic compression responses.<ref>{{cite journal |last=Godshall|first=D |year=1971 |title=Frequency response, damping, and transmissibility of top loaded corrugated containers|journal=US Forest Products Laboratory Report|volume=160 |issue= |series=FPL|pages= |id=|url=http://www.fpl.fs.fed.us/documnts/fplrp/fplrp160.pdf|accessdate=28 June 2011 |quote= }}</ref> [[Package testing]] methods are available to evaluate these compression dynamics.
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