Hamid Ahmadian - Center of Excellence in Experimental Solid Mechanics and Dynamics, School of Mechanical Engineering,
Hassan Jalali - Department of Mechanical Engineering, Arak University of Technology, University street

Onboard excesive vibration is a main concern in designing ship structures. There are manyexcitation sources- i.e. propellers, shaft lines and engines- which may result in exesive vibration.Due to the interaction between shaft lines and ship structure, unbalanced propellers ormisaligned shafts can cause the whole shaft to vibrate excesively. Ship structural vibration affectsthe crew and passengers comfort and causes fatigue failure in equipments. In this papervibration measurements are conducted on shaft lines of a ship structure in order to determine the natural frequencies. The natural frequencies can be used in constructing the FE models for the shaft lines or diagnosing the source of vibration in ship structure.

vibration measurement; natural frequency; shaft line