Tank Roll Over Test

Tank Car Fittings Protection

In the 1st phase of this project, potentially exposed tank car fittings (in derailment scenarios) were identified to investigate their survivability in such scenarios.  After evaluation of the base case results, various protective structure concepts for the fittings have been developed and their efficacy has been predicted through finite element analyses. Some of the concepts developed have shown remarkable effectiveness under the simulated conditions.  Under this project, a benchmark test (under controlled conditions) of a tank car with existing fittings was planned.  SA has designed, manufactured and installed a test fixture to allow rolling of a tank such that the fittings would impact the target location on the ground.  Testing of proposed fitting protection solutions, skid and roll bar systems will follow the benchmark test.

The test tank was instrumented with strain gages and accelerometers.  A high-speed video camera was used to capture the impact dynamics.  The car was loaded with water to simulate lading capacity and appropriate inertia.

Results of the tests are being analyzed and would soon be reported.  In the meanwhile, preparation for testing of tank retrofitted with protective skid and roll bars is underway.

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The objective of the project was to identify potentially exposed tank car fittings (in derailment scenarios) on cars carrying hazardous material, and to investigate their survivability in such dynamic impact scenarios using analytical tools such as LS-DYNA.  LS-DYNA is a special purpose explicit finite element solver, designed specifically for impact and crash analysis.

Potential solutions for protecting the fittings under roll over impact situations were to be developed in the 2nd phase of the project.

SA investigated the statistical accident data on various tank car and commodity types and identified that the top fittings on non-pressure fuel and acid service cars would be the most exposed/susceptible. A representative fuel oil non-pressure tank car design was then selected for detailed analysis. A comprehensive FEA model of the tank car, stub sill structure and top fittings was constructed in ANSYS using solid elements with mapped meshing. The taper of the tank was also included along with simplified modeling of the fasteners on the fittings. This model was ported to LS-DYNA for dynamic impact analysis. The model simulated a rollover of the tank car and evaluated the stresses and deflections experienced by the fittings in such conditions. The simulation includes non-linear material properties as well as complex contact definitions between various parts of the tank and the ground surface.

The identified rollover scenario simulations showed complete failure of the existing fitting structure. This indicates that in a derailment situation with the tank car rolled over, the tank contents (liquid or gas) are very likely to leak.

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