A novel approach to analysing and simulating railcar shock and vibrations

This paper presents the preliminary findings of an experimental research programme aimed at determining the character of the shocks and vibrations that occur during rail transport in Australia. The main purpose of the research is to generate information to enable more accurate simulation of railway vibrations in the laboratory, so as to give packaging designers a real opportunity to optimize their designs and, if necessary, develop protective packaging systems specific to a particular distribution environment. One of the hypotheses to be tested is that the railway shocks and vibrations that occur in Australia vary significantly in nature from the spectral representations given in test standards. This paper presents the results of analyses carried out on a number of measurements undertaken during 2004-2005 on the Melbourne-Perth railway. One of the most significant findings is that the spectral shape and spectral bandwidth of the measured vertical vibrations vary significantly from those given in test standards. Also, there is strong evidence to show that vertical vibrations comprise two main elements: rigid-body vibrations and structural vibrations. The results show that structural vibrations often occur in bursts caused by the impulsive nature of forces at the wheel-rail interfaces or as a result of longitudinal impulsive loads between railcars. The paper concludes by proposing a method by which the intermittency of these structural vibrations can be simulated by superimposing randomly occurring high-frequency vibration bursts onto the main rigid-body random vibrations. The outcome, it is argued, is a simulated signal that is a more truthful representation of the real process. Copyright (c) 2006 John Wiley & Sons, Ltd.