Dynamic Simulation of a Railroad Freight Car Using a 1/12 Scale Physical Model

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Author(s): Hussain, S. M. A., Willis, T., Kumar, S.
Corporate Author(s): Department of Mechanics, Mechanical and Aerospace Engineering, Illinois Institute of Technology
Corporate Report Number: IIT-TRANS-77-4
Date of Publication: 1977-08
Pages: 109
Contract: DOT-OS-40103
DoD Task:

This report describes the design, fabrication and testing of 1/12 scale model rail-car which is based upon a similar but more limited capability model of the Association of American Railroads. Then model is a 1/12 scale of a 100 ton rail-car, which has its center of gravity close to a maximum allowable 98 inches from rail. Input to the model is provided at the wheels by a cam and lever arrangement which simulates the vertical and lateral track irregularities of different track dynamic profiles. Longitudinal input is provided to the freight by a solenoid. The cams are rotated by a variable speed motor calibrated to give the equivalent speed of the car in m.p.h. The vibration environment within the car body and its truck was measured by accelerometers. Tests were performed to correlate the results with published data obtained from a full-size car. The effects of speed, load, friction damping and spring travel on the car body vibration environment and truck vibrations were determined and also the critical roll and bounce speeds were obtained. The results of these tests are presented here in the form of vibration spectrogram transmissibility curves, power spectral density curves and plots of acceleration versus speed. 1. The roll and bounce critical speeds found were around 17.5 and 45 m.p.h. 2. An increase in load decreases the car body vibration levels and increases the truck vibrations. 3. There is an optimum friction damping where the car body vibrations and transmissibility are minimum. Further increase or decrease in this damping level causes increase in vertical car body vibrations. 4. An increase in spring travel reduces the vibration levels in the car body as well as of the trucks.

Provenance: S. Kumar

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