Search Results

Noise and vibration engineers make many frequency domain measurements during the development of an automobile. These measurements are used to develop prototype hardware or, in some cases, to increase the “degree of belief” of a computer model. In the case of hardware development, the engineer frequently must evaluate competing designs while, in the case of computer modeling, the engineer often must investigate the fidelity of his/her assumptions. In either instance, the engineer will perform some type of experiment to answer the question(s) of interest. Many experiments, however, may be compromised by undesired variability associated with the data. This variability may arise from sampling uncertainty, transducer noise and digital signal processing bias to list a few. While most engineers consider this variability, they often do not account for other sources of variability such as experimental set-up, car to car differences and environmental conditions.

This paper examines the feasibility of using eigenvalue modification as the effective algorithm for interactive modal analysis. The dynamic characteristics of a cantilever beam are determined experimentally and compared to the results of an analytical study. The model is then modified with the addition of mass and stiffness. The results predicted using eigenvalue modification theory on the analytical model compare very favorably with experimentally determined results.

The use of signature analysis to determine the acceptability of parts in a production line quality control situation is highly desirable. Specifically, the use of acoustic signature analysis is attractive due to the relaxed constraints in terms of fixturing the part in preparation for analysis. This study discusses techniques presently being investigated which rely on knowledge of the modal coefficients to direct the area of investigation.

The history and structure of the Recreational Ecological Vehicle Design Competition, REV-74, is discussed. In this competition, held at Houghton, Mich., several universities designed and constructed all-terrain vehicles which were evaluated in a series of test events. The University of Cincinnati's six-wheeled all-terrain vehicle is described in detail. Features included in the discussion are the vehicle's twin hydrostatic drive transmission, independent suspension, high-frequency muffler, and jet pump drive for water propulsion.