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A new method for extracting order related signal components from rotating machinery data is proposed. The notion of the Gabor expansion and the Gabor transform for time/frequency analysis are introduced and the relationship between them is described. Gabor Order Tracking (GOT) is offered as one possible masking strategy for extracting desired signal components from the time/frequency domain for reconstruction in the time domain. Practical examples are utilized to illustrate the proposed method in comparison to established techniques.

A new approach of estimating the modal parameters of operating piston engines is presented. The developed approach represents a combination of concepts from currently existing analyses such as the natural excitation technique (NExT), conditioned input analysis (CIA), and conditioned source analysis (CSA), and is hence termed “conditioned NExT analysis (CNA)”. NExT analysis can be employed to estimate modal parameters of structures in their naturally excited states. However, the existence of strong combustion induced periodic forcing makes the application of NExT analysis to operating engines difficult, if not impossible. CIA and CSA, built on concepts of partial and virtual coherence respectively, can effectively condition operating engine vibration data so as to remove any periodic energy associated with the process of combustion.

An enhanced method for solving multi-input systems is presented which builds on the concepts of partial coherence using conditioned input analysis and virtual coherence using principal component analysis. Conditioned source analysis expands the definition of partially coherent inputs to include partially coherent input arrays. Each input array may describe a complex multi-dimensional source. The cross correlated input array is replaced by its equivalent principal component decomposition and conditioned from subsequent inputs/arrays using the techniques for determining partial coherence. The extension of existing theory to include conditioned source analysis is described and the method is illustrated on a lumped-parameter model. A practical application of the technique is also presented where the component of noise and vibration in an engine which is statistically related to combustion is separated from mechanically induced sources.

Continuous improvement of the NVH performance of current production powertrains is a necessary goal of domestic auto makers. In order to maintain a competitive product, it is necessary to re-evaluate proven hardware against demanding NVH performance targets established by the competition. This paper describes an NVH investigation of component modifications to the Ford 3.8 liter powertrain. The hardware investigated includes: ribbed and isolated rocker covers, drop-in roller fulcrums, forged steel and cast iron crankshafts, crankshaft bending damper, full skirt girdle, one piece bearing cap (bearing beam), reduced weight pistons and rods, ribbed sump, and alternate crank pulleys and water pump. At the conclusion of these investigations, a complete powertrain was assembled based on the recommendations generated in this project. The NVH features included in this “quiet” 3.8 liter engine and the rationale behind the decisions are described.