Technical Reports

Theoretical Manual and User's Guide: Longitudinal-vertical Train Action Model

  • 01
  • Apr
  • 1978
AUTHOR: Yin
OFFICE: RPD
REPORT NUMBER: DOT/FRA/ORD-76/278
SUBJECT: Hazardous Materials
ABSTRACT: A mathematical model for simulating the longitudinal-vertical motion of railroad cars in impact situations is described in this document. Development and validation of the model was part of a study concerned with the phenomenon of coupler bypass resulting from impact or squeeze. The model represents each car as an idealized dynamic system, consisting of springs, masses, and dampers and possessing up to 6 degrees of freedom (12 state variables) per car. The degrees of freedom correspond to the longitudinal, vertical, and pitching motion of car bodies, lading motion, and truck motion (front and rear separately). The model is capable of representing friction draft gears as well as hydraulic cushioning devices. The model accounts for friction between truck side frame and bolster, possible separation of the truck center plate from the truck bolster, and coupler disengagement. A limitation of the model is that, in the absence of more accurate information, the force-deflection relationship of car underframes is represented by linear springs. However, it can be readily modified to represent non-linear force-deflection relationships once those relationships are quantified.

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