At the Duke University Injury Biomechanics Lab, Rachel Lance is researching the Civil War submarine, H.L. Hunley, which was the first ever submarine to sink an enemy ship in combat. However, after the Hunley detonated its 135 lb. black powder charge and sank the USS Housatonic, it mysteriously disappeared until 136 years later, when it was discovered and raised in 2000.
Successive conservation efforts have failed to reveal the reason for its sinking. Surprisingly, there was no hull damage done and the crew’s remains were seated peacefully inside with no injuries or attempts to escape. Rachel’s underwater explosion research focuses on the physics of the blast transmission, which are very dependent on the hull style and shape.
As part of her work, Rachel has created a complex 3-D test model of the vessel, the CSS Tiny, to emulate how the blast occurred. Her finite element simulations incorporate compressed gas to rupture Mylar membranes, consequently creating shock waves without the need for live explosives. Through the Co-Lab’s laser cutter access, Rachel was able to cut new membranes at any time. With up to 15 membranes used for each simulation, the Co-Lab has proven extremely critical to the success of Rachel’s project.
Furthermore, with help from the Co-Lab team, Rachel has printed a 3D aesthetic model and a series of brackets, used to facilitate documentation and mechanical functionality of the test models. Reusable phone brackets were designed to hold a phone for photo and video documentation of the simulations at the Duke reclaimed water pond and custom brackets were designed to mount pressure gauges inside a small enclosed space of the model submarine.
Rachel purposes that a secondary blast transmitting straight through the hull from the explosion caused pulmonary blast trauma that killed the whole crew instantly. Her findings from the blast wave experiments have been released to numerous publications and have been highly regarded by the science and research community. Congrats Rachel!