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[[File:US military drum compression test.jpg|thumb|Compression test for steel drum]]
The '''container compression test''' measures the [[compressive strength]] of packages such as boxes, drums, and cans. It usually provides a plot of [[Deformation (engineering)|deformation]] vs compressive [[force]].
It is commonly used to evaluate [[shipping container]]s made of [[corrugated fiberboard]] as well as [[wooden box]]es and [[crate]]s. Industrial and consumer packages other than boxes can also be subjected to compression testing: drum, pail, bottle, tub<ref>
{{cite journal
| last =Varzinskas | first =Visvadas
| volume =50 | issue =4 | pages =57–65
| url = http://www.matsc.ktu.lt/index.php/erem/article/viewArticle/42
}}</ref> etc. Package components are also evaluated for compression resistance.<ref>{{Citation
| last =Urbanik |first =T. J.
| last2 =Lee |first2=S. K
}}</ref>
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.
==Test procedures==
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 {{convert|1/2 inch (12.5 |in/min|mm) per minute/min}} 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.
The results of the constant rate of compression test can be:
==Corrugated box testing==
Corrugated shipping containers are exposed to compression hazards during storage and shipment. Proper compression strength is a key performance factor.
===Factors potentially affecting test results===
===Estimations===
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|date=July 1981 |title=Effect of paperboard stress strain characteristics on strength of singlewall corrugated boxes|journal=US Forest Products Laboratory Report|volume=401 |series=FPL}}</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|author2=Gander, Wachuta |date=August 1963 |title=Compression strength formula for corrugated boxes|journal=Paperboard Packaging |volume=48 |issue=8 }}</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 compression requirement===
==Dynamic compression==
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) 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 |series=FPL|url=http://www.fpl.fs.fed.us/documnts/fplrp/fplrp160.pdf|access-date=28 June 2011 }}</ref> [[Package testing]] methods are available to evaluate these compression dynamics.
==See also==
*[[ASTM]] Standard D7030 Test Method for Short Term Creep Performance of Corrugated Fiberboard Containers Under Constant Load Using a Compression Test Machine
*German Standard [[Deutsches Institut für Normung|DIN]] 55440-1 Packaging Test; compression test; test with a constant conveyance-speed
*[[International Organization for Standardization|ISO]] 12048 Packaging—Complete, filled transport packages—Compression and stacking tests using a compression tester
==Further reading==
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