VIBRATION SURVEY ON U. S. ARMY SHIP LT. COL JOHN U. D. PAGE (BDL-1X).
Research and development rept.,
DAVID TAYLOR MODEL BASIN WASHINGTON D C STRUCTURAL MECHANICS LAB
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A vibration survey was conducted on U. S. Army ship LT COL JOHN U.D. PAGE BDL-1X to ascertain the cause of excessive vibration of bulkheads bounding the aft ballast tanks in the area of the shaft alleys. The tests were conducted for two tank loading conditions during steady runs at various propeller pitch settings and during maneuvers. Natural frequencies of the bulkhead plating panels for loaded tanks were nearly the same as double blade frequency at 830 engine rpm, whereas those for empty tanks were considerably higher. Vibration levels were unacceptably high only for the condition of loaded tanks and with propeller pitch settings larger than 0.5 at 830 engine rpm. The vibration of the bulkhead panels can be traced to a sharp increase of vibration amplitudes of the propeller housing for pitch settings larger than 0.5 and engine speed of 830 rpm. This sharp increase of vibration level is probably of hydrodynamic origin. Author
- Marine Engineering