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In recent truck applications, single-piece large-diameter propshafts, in lieu of two-piece propshafts, have become more prevalent to reduce cost and mass. These large-diameter props, however, amplify driveline radiated noise. The challenge presented is to optimize prop shaft modal tuning to achieve acceptable radiated noise levels. Historically, CAE methods and capabilities have not been able to accurately predict propshaft airborne noise making it impossible to cascade subsystem noise requirements needed to achieve desired vehicle level performance. As a result, late and costly changes can be needed to make a given vehicle commercially acceptable for N&V performance prior to launch. This paper will cover the development of a two-step CAE method to predict modal characteristics and airborne noise sensitivities of large-diameter single piece aluminum propshafts fitted with different liner treatments.

This paper describes recently developed test methods and instrumentation to address the specific noise and vibration measurement challenges posed by large-diameter single-piece tubular aluminum propeller (prop) shafts with high modal density. The prop shaft application described in this paper is a light duty truck, although the methods described are applicable to any rotating shaft with similar dynamic properties. To provide a practical example of the newly developed methods and instrumentation, impact FRF data were acquired in-situ for two typical prop shafts of significantly different diameter, in both rotating and stationary conditions. The example data exhibit features that are uniquely characteristic of large diameter single-piece tubular shafts with high modal density, including the particular effect of shaft rotation on the measurements.

The objective of the paper is to outline a CFD based lumped parameter method that compares the thermal performance of brake rotors, predicts the transient temperatures and brake lining wear in vehicle. A two-pronged approach was developed for this purpose. A rotor stand-alone model was used to predict rotor performance curves. Simultaneously heat transfer coefficients of the brake rotor were computed corresponding to the rotor performance curves and the appropriate heat transfer correlations were established. The second part of this approach involved developing a brake model in a vehicle and solving for the air flow through rotors in different vehicles at various speeds. These rotor flows were cross-referenced with the rotor performance curves, generated earlier for that rotor, to compute the heat transfer coefficients in the vehicle.