Update on Ongoing Tank Car Crashworthiness Research: Predicted Performance and Fabrication Approach

Research is currently underway to develop strategies for maintaining the structural integrity of railroad tank cars carrying hazardous materials during collisions. This research, sponsored by the Federal Railroad Administration (FRA), has focused on four design functions to accomplish this goal: blunting the impact load, absorbing the collision energy, strengthening the commodity tank, and controlling the load path into the tank. Previous papers have been presented outlining the weight and space restrictions for this new design, as well as the approach being taken in developing the design. The performance goals for the new car have also been outlined. A key goal for the new design is the ability to contain its lading at four times the impact energy of the baseline equipment. Presently, a preliminary design has been developed that will incorporate these four functions together. This new design features a conventional commodity tank with external reinforcements to strengthen the tank. The reinforced tank is situated on a structural foam cradle, within an external carbody. This carbody has been designed utilizing welded steel sandwich panels. The body is designed to take all of the inservice loads, removing the commodity tank from the load path during normal operations. Additionally, the carbody panels will serve as an energy-absorbing mechanism in the event of a collision. Preliminary steps for fabricating and assembling the new tank car design have been outlined. These steps were developed with the intention of paralleling existing tank car fabrication process as much as is practical. Using the commercial finite element analysis (FEA) software ABAQUS/Explicit, the improved design has been analyzed for its response to an impact by a rigid punch. Simulations of two generalized impact scenarios have been made for this rigid punch impacting the improved tank car head as well as the improved tank car shell. Results of these analyses, including the force-displacement curves for both impacts, are presented within this paper. These results show that an improved-design tank car can contain the commodity for a head impact with eight times the energy of the baseline car, and four times the energy for a shell impact.