A professor of applied mechanics at the Massachusetts Institute of Technology has borrowed a materials analysis technique developed for the car industry and applied it to pipe failure prediction software for offshore drill rig designs. A first test showed a very close correlation between predictions of fracture patterns in the riser of a sunken drill rig, with video images captured at the scene.
Researchers at MIT's Impact and Crashworthiness Laboratory used video from the April 2010 explosion of the drill rig Deepwater Horizon in the Gulf of Mexico for the project. They applied techniques used to simulate material deformation in car crashes to predict how pipes may fracture in a drill rig accident.
Their model accurately predicted the location and propagation of cracks in the oil rig's riser—the length of pipe connecting the surface drilling platform to the sea floor. In a side-by-side comparison, the researchers found that their model's reconstruction closely resembled an image of the actual fractured pipe taken by a remote-operated vehicle shortly after the accident.
The model used technology developed by applied mechanics professor Tomasz Wierzbicki for car-crash safety testing. His technique captures the propagation of distortion in stressed material samples. The method uses a high-pressure water jet to cut a sample from a candidate material, such as steel, which is then sprayed with a fine pattern of speckles to cover the surface with tiny dots.
After the spray dries, the sample is clamped into a machine and subjected to loading. A camera captures changes in the dot pattern as the sample crumples. The changes are plotted on a grid to show exactly when and where deformations occur under a given loading scenario.
For this test the researchers used the stress test of a material whose properties are believed to closely match the steel used in the riser. They modeled the mass of the rig and pipe, and then slowly “sank” the rig, thereby putting bending forces on the pipe.
The predicted fractures that developed closely matched those seen in videos from the scene of the real disaster.
