An in-service dynamic model of a diesel railcar from operational modal analysis and finite-element model updating

Hanson, D., Winton, M., Randall, R.B., Ford, R.A.J., Thompson, D.J., Waters, T.P. and Antoni, J. (2008) An in-service dynamic model of a diesel railcar from operational modal analysis and finite-element model updating. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 222 (4), 313-320. (doi:10.1243/09544097JRRT105).

Abstract

Builders of passenger rail vehicles need methods for predicting vibrational behaviour so that they can meet ride quality specifications. Conventional finite-element (FE) models used for stress analysis may not be accurate enough for this because of imponderables such as the stiffness of spot-welded joints. One solution is to adjust FE models based on vibration measurements. This model updating is now possible using commercially available software. Usually, the updating is based on vibration tests carried out under laboratory conditions, which may produce different results from normal operation. In this paper, two simple FE models of a railcar are updated using vibration data obtained from a newly designed railcar under in-service conditions. Measurements were made on a railcar loaded to represent crush-loaded conditions and running down track, with the only excitation that naturally occurring due to track roughness, engine excitation, aerodynamic loading etc. Unlike standard laboratory vibration testing, this input excitation could not be measured, so advanced forms of output-only analysis were required. By using these data as input to a commercial updating package, the simple FE models have been updated and the effectiveness of the technique assessed.

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Contributors

Author: D.J. Thompson

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