Full-Scale Optical Experiments on the Explosive Failure of a ULD-3 Air Cargo Container

Understanding the failure mechanism of an air cargo container subject to an internal explosion is important to progress in aircraft hardening. Here, full-scale ULD-3 container explosions were imaged using a shadowgraph technique employing a 5m-square retroreflective screen and a high-speed video camera. The experiments revealed that the shock wave from a terrorist-scale explosion can be highly suppressed by typical luggage contents including clothing, paper, etc., even though the blast is otherwise sufficient to destroy the container. While luggage fragments were hurled at high speed through the container walls, there was little evidence of any quasi-static overpressure damage. Another key result is the demonstration of the practicality of optical imaging methods in full-scale aircraft hardening experiments. Future work includes adapting the present optical setup to also record high-speed stress of the cargo container walls, optical refinements including laser illumination to suppress direct light from the explosion, and an effort to better measure the structural failure in order to more exactly define the performance criteria of hardened containers and liners.