The State of Stress of Transportation Packages During Hypothetical Accident Free-Drop Impact

In general, only stress-based design criteria are used and accepted by regulatory agencies to demonstrate transportation package structural performance by analysis. However, as stated in the regulatory guidance, other criteria may be accepted on a case-by-case basis. There are efforts to develop alternate design criteria, based on strain or strain energy density, to demonstrate acceptable structural performance of packages under the HAC free drop. Prior to developing such design criteria, two elements must be understood and developed: (1) the failure mechanism from strain or strain energy density and (2) a theory of failure. However, in order to understand the failure mechanism and to develop a theory of failure, the stress state behavior (stress fields) must be known. As a first step, this paper examines and reports the stress states for free-drop impact loadings on two transportation packages currently in use.