| This thesis presents the development of a train derailment computer model. The planar model is based on coupled sets of 5 degree of freedom sub-system models for each rail car, and includes coupler body reaction forces, car-ground reaction forces, brake forces, and car-to-car collision forces. The model allows constraint removal to model coupler failure and derailment conditions. The differential equations of motion for the train system are derived using Lagrange's equations with added multipliers.; The complete computer model was validated against the well known Mississauga derailment of 1979. The model resulted in 24 derailed cars, identical to the actual event, and a --11.7% error in accident site area. The major collisions produced by the model correlate well with the damage which occurred at the actual event.; The derailment model was also tested for sensitivity to parameter variation about a baseline train. The changes in the model outcome for variations of +/-20% and +/-50% for car mass, train length, train speed, braking force, ground reaction force, and derailment quotient (L/V ratio) were performed. The outcomes were compared by number of derailed cars, peak collision forces, and the length, width, and area of the accident scene. The results show the model to be numerically stable within the +/-50% boundaries, and to produce outcomes physically consistent with the variations in the parameters. Train speed, car mass, and train length were the parameters which had the greatest effect on the number of derailed cars and the peak collision force.; Finally, the Mississauga derailment model was tested with alterations to the braking model. The results show that instantaneous application of brake forces approaching wheel lockup significantly reduced the severity of the Mississauga derailment model results.; Recommended future research includes the study of the effects of braking, car placement, mass, and length, and the surrounding terrain near the rail lines on the severity of derailments. |
