Search Results

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 installation of various liners into the propeller shaft tube is a traditional driveline NVH treatment to attenuate driveline vibration. The most commonly used liners include rolled paper, C-cut cardboard, corrugated cardboard, etc. These traditional liner treatments are expected to provide damping to the driveline system to reduce the vibration levels. However their added level of damping and effectiveness to the driveline system are limited, particularly when dealing with driveline gear mesh vibration and noise. This paper presents a novel type of liner treatment - tunable liners. The liner is designed such that it functions as a tuned dynamic vibration absorber. Through proper design of the liner, it can be tuned for bending and torsion modes at the same time. The liner design parameters and their impact on the frequency tuning are analyzed and studied through both physical testing and FEA analysis.

The need for improved axle NVH integration has increased significantly in recent years with industry trends toward full-time and automatic four wheel drive (4wd) systems. Along with seamless 4wd operation, quiet performance has become a universal expectation. Axle gear-mesh noise can be transmitted to the vehicle passenger compartment through airborne paths (not discussed in this paper) and structure-borne paths (the focus of this paper.) A variety of mounting configurations are used in an attempt to provide improved axle isolation and reduce structure-borne transmission of gear-mesh noise. The configuration discussed in this paper is a 4-point vertical mount design for an Independent Front Drive Axle (IFDA). A significant benefit of this configuration is improved isolation in the range of drive torques where axle-related NVH issues typically exist.