Use of
Vibration Measurements and FEM Predictions to Evaluate Location of
Mr. Davis Hill, Northrop Grumman
Jason Hartmann, Nothrop Grumman
Abstract:
Excessive vibration in surface ships is a design concern that affects both
equipment and ship personnel. This excessive vibration concern is more
critical in the aft one third portion of a surface ship due to the pulsating
pressure loads from the propeller blade on the shell plating. The CVN78
arrangement proposes the movement of the island house into the aft one third
portion of the ship.
During the CVN76 ship trials, vibration measurements were taken at the island
house and at the bent legs located below the CVN76 island.
Further, vibration measurements of the bent legs located below the proposed
CVN78 island location were taken. The bent leg measurements are used as
inputs in a finite element model of the island and its support structure.
A CVN76 FEA model is performed to validate the modeling approach by comparing
calculated island house responses to measured responses. The approach is
then applied to a similar FEA model of the CVN78 island configuration. A
comparison of the vibration severity from CVN76 to CVN78 is made.
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