Drop test energy balance by computer-graphics analysis of high-speed videotape

This activity was prompted by the concurrent arrival of two items at our Department of Energy Safety Analysis Report for Packaging (DOE SARP) review offices: (1) high-speed videotape of a regulatory 9-m drop test of a shipping package, with the usual cross-hatched white background; and (2) computer-aided graphics capability. Again we conjectured that the cross-hatched white background was probably provided to allow determination of the package velocities and energies during the portrayed event. But no SARP we had ever seen had made use of this potential. We also realized that computer graphics would make it easier to produce enlarged frame-by-frame copies of the tape for analysis, than traditional chemical processing of the film. The synergistic outcome was that we decided to attempt to determine by using the tape and a computer, whether the energy E{sub dmg} absorbed by damage to the package during the first impact, plus the energy E{sub rmg} remaining in the package after the first impact, can be shown to be reasonably equivalent to the drop energy E{sub drop}, i.e., E{sub dmg} + E{sub rmg} = E{sub drop}. The calculation of the three energy terms is discussed in the following sections, preceded by a description of the package subjected to the videotaped drop test, and a calculation of the parallax error involved in the interpretation of the videotaped images.