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Test Facilities for Vibrations and Acoustics can be very complicated. With the addition of necessary high power motor dynamometers for load application, the complexity of the test cell increases dramatically. The motors and subsequent additional fixtures and shafts necessary to apply loading conditions can produce additional source noises that would interfere with test measurements. In addition, facility interfaces can dramatically influence the test cell setup and reduce the measurement capabilities. This paper addresses common considerations needed in considering a new test cell for driveline vibration, acoustics, efficiency, and durability testing using motored dynamometers. In addition to outlining common design points, a practical application of 2 new dynamometers utilized for vibration, acoustics, efficiency, and durability testing and their subsequent capabilities are outlined.

Correlating a bench test stand to predict the response of a driveline gearbox in the vehicle can be very difficult. Many sources of variation and error may prevent correlation. This paper outlines the issues related to both vehicle and bench testing that prevents proper correlation. The importance of understanding both the NVH measurements and statistics are vital to proper interpretation. The identified issues are backed up with real test cases where these issues occurred in a series production gearbox program. A successful correlation case study is presented for comparison.

Identification of vibration transfer paths is critical to proper isolation of vibration excitations from becoming objectionable noise in a vehicle. Traditional transfer path methods involve comparing vibration inputs to the outputs of each joint. This method can be time consuming and inefficient due to a complexity of paths. A new statistical method was developed to improve the efficiency of testing. This method requires the measurement of the excitation vibration input at each joint of the source component and response sound measurements in the vehicle. Identification of transfer paths using regression analysis will determine the trouble paths to scrutinize.

Determination of the critical speed of a driveshaft is critical for development and validation of its design for use in a vehicle because of its destructive effects. Typical calculations to determine critical speed are either over simplistic and not very accurate or very complicated requiring CAE software and capabilities. An analytical five-section non-prismatic beam model was developed to fill in this gap. The model was developed to compute the critical speed in a worksheet and proven to be as or more accurate as utilizing FEA methods. The model worksheet calculates the critical speed for one-piece conventional driveshafts and adapted for Visteon's Slip-In-Tube (SIT) driveshafts.