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The simulation model developed and validated by the authors [1] for vehicle chassis transmissibility of steering shimmy and brake judder is used to analyze the transmissibility mechanism and quantify the relative importance of system factors, through modal analysis around equilibrium point and a virtual DOE (design of experiment) process. Contributing chassis vibration modes are discovered, relative importance of chassis factors is efficiently determined, and potential areas for improving chassis shimmy/judder sensitivity are identified. The DOE results are further confirmed by the comparison of simulated and on-road measured shimmy/judder change with the specification change of key factors. Also presented is some successful application of the simulation technology and analysis results to vehicle development.

The paper presents the results of a study on the experimental determination and theoretical prediction of the source flow ripple generated by a fluid power piston pump. This work supports the development of quieter pumps with better fluidborne noise characteristics. As an effective experimental method, the “2 Pressures/2 Systems” method is introduced and used to determine the actual value of the source flow ripple and confirm the prediction results. A theoretical model is derived by the inclusion of the compressibility of the fluid, the fluid momentum in the cylinder chamber and relief grooves, and the pressure-dependent effective bulk modulus of the fluid containing air. The accuracy of the model is confirmed by the comparison of predicted and measured results. Finally, the effectiveness of the experimental method is presented.