Lading Effects on Tank Car Impact Response
The application of the puncture analysis capabilities to assess the effects of the tank lading for various impact conditions. This includes both the dynamic effects of the lading on the impact response and the effects introduced by the physical characteristics of different ladings (e.g. density and vapor pressure).
A series of analyses were performed to evaluate the effects of lading on the tank car impact and puncture behavior. The initial analyses evaluated the detailed impact dynamics of the lading and the various modeling methodologies and approximations that can be used for the lading. For side impacts, the effects of different modeling methodologies are relatively small and simplified methodologies can be applied without introducing large errors in the assessment of puncture forces and energies for most impacts.
The head impact analyses produced significantly different results from the side impacts. The shorter duration head impact loading resulting from a relatively stiff tank structure and the longer duration response for the fluid sloshing results in a partial decoupling of the tank and fluid motions. For the 18 mph head impact analyzed, less than 10% of the lading weight contributed to the tank impact resistance during the primary impact event.
The other series of analyses performed were to assess the effects introduced by the physical characteristics of different ladings (e.g. density and vapor pressure) on the puncture resistance. The analyses show that these effects can significantly influence the puncture resistance of the tank cars for different commodities. These analyses provide data that can be applied for formulating appropriate tank specifications and puncture protection levels for various commodities
There is ongoing research to develop strategies for improving railroad tank cars so they can maintain tank integrity for more severe accident conditions than current equipment. Research results are being used to develop tank car designs and to inform rulemaking by the Federal Railroad Administration (FRA).
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