Scaling issues related to modeling of railroad Car Damage I - Derailment, plastic deformation, rupture, and impact

The awareness and reaction to the vulnerability of transportation systems have stepped up significantly since the increase in terrorist activity over the last several years. Larger conveyance vehicles are especially susceptible to attack and have the potential for doing the most damage to people and surroundings in an accident of any type. Trains are the largest and most dangerous in this respect. This paper is the first of two having to do with issues connected with scaled-model testing of railroad cars in serious accidents. The present paper analyzes mechanical issues due to (1) the derailment itself, (2) plastic deformation of the railway cars, (3) rupture of the cars, and (4) initial impact. The premise of this paper is the fact that full-scale tests of railroad cars are for the most part prohibitively expensive and the corresponding data are limited. Small-scale models of trains are preferable, but the dimensions cannot be resized without having many other physical parameters scaled as well. Sometimes the problems can be reduced easily; often they cannot. In this paper, insight to the four damage mechanisms listed above, and ways to scale them, are analyzed using the mathematical technique of dimensional analysis. Also identified are physical phenomena that do not lend themselves to easy rescaling. (c) 2005 Elsevier Ltd. All rights reserved.