Design Evaluation and Field Qualification of a Damping System for an Auxiliary Power Unit,
DAYTON UNIV OH RESEARCH INST
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A turbine engines used to operate an auxiliary power unit was incurring resonant vibration induced fatigue failures in the inlet guide vanes IGV. Field test data from the IGVs revealed high stress levels at frequencies corresponding to the second bending and second torisional resonances. The operational environment required a damping system to be functional over the temperature range of -50 F and 150 F. The damping system had to survive the high airflow and erosion environment associated with the inlet of the engine and also had to be field installable. A computer aided design procedure was used to develop the required damping design. The final design was proof tested in the laboratory and demonstrated an 86 percent stress reduction. Engine test stress reductions agreed well with the laboratory results. After successful engine test evaluations, a one year field evaluation successfully demonstrated the field installation procedures and the durability of the damping system.