Dynamics of Package Cushioning

ECHANICAL damage is a common occurrence in the transportation of packaged articles. The causes of failures are generally inadequate protective cushioning, lack of ruggedness of the outer packing container, or occasional abnormal weakness of the packaged article. The first of these difficulties is the subject of this paper. One of the major influences in reducing the incidence of mechanical failures of packaged articles in recent years has been the use of the drop test. The drop test is performed simply by raising the package to a specified height and dropping it to the floor. The package and its contents are then examined for damage. This is a go-no-go test and requires a large number of samples before a reliable estimate of quality can be made. An adequate number of tests is prohibitive when the article packaged is costly. In such cases it is important, and in any case it is useful, to supplement the drop test data with measurements and calculations. It is also possible to evolve rational procedures for designing packages, as described in the present paper, so that a particular product will survive a drop test at any specified height, with a known factor of safety and with a minimum amount of space assigned for cushioning. The drop test then becomes only a check instead of playing an integral role in a cut and try design procedure. Assuming that the outer container is adequate, the survival of a packaged article in a drop test still depends upon a large number of factors descriptive of the mechanical properties of both the cushioning medium and the packaged item.