Evinrude 30 MFE Outboard, Test Configuration Torsional Vibration Analysis
US ARMY TARDEC WARREN United States
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A collaborative effort was undertaken between Keweenaw Research Center at Michigan Technological University MTU and US Army Tank, Automotive, Research, Development and Engineering Center TARDEC, Ground Vehicle Power and Mobility GVPM to evaluate the performance of an Evinrude 30 MFE outboard engine for watercraft. To support design of this test setup, and also to provide information into an assessment of the Evinrude 30 MFEs applicability to Army ground applications, a torsional vibration analysis TVA was completed at GVPM. The linearized eigenvalue solution of the Evinrude 30 MFE torsional vibration model indicates that the first resonant frequency will be present at approximately 29 Hz. This mode shape is characterized as the powerhead inertia being out of phase with the lower unit and dynamometer, which correlates with industry input suggesting that the lower unit of small outboards tends to fail when coupled to a dynamometer. As originally designed, engine speeds of approximately 750 to 1050 RPM 25-35 Hz will most likely rapidly accumulate damage to the lower unit in this test configuration.
- Marine Engineering