Noise & Vibration
Services tailored to your needs
Strong noise and vibration in working and living spaces can be the origin of reduced crew performance and passenger discomfort. Moreover, excessive vibration might cause damage at the structure, machinery and equipment. GL assists to avoid noise & vibration problems during all phases of a ship's life, beginning from the early design stage, during building and commissioning or if unexpected noises or vibrations occur during operation.
Global Structural Vibration Analysis
This analysis comprises several steps. After preparation of the finite element
model of the ship, the mass distributions being typical for the individual
ship's service are applied. Then the ship's natural vibrations are computed to
identify critical resonance conditions. Subsequently, the expected vibration
level distribution over the whole ship is computed for the relevant power
conditions. Through extensive post processing a clear idea is gained how to
counteract vibration most effectively. For this, knowledge of the strength and
frequencies of the vibration sources is of utmost importance. Excitations from
engines, propellers, vortex shedding and the sea way can be considered. Finally,
the predicted levels are compared to the target values and it is assessed
whether design modifications are advisable. Stringent automation of the analysis
process enables us to investigate the effect of design variants in very short
time.
GL offers to
- reduce the risk of exceeding contractual vibration limits
- to assess the cost-benefit ratio of structural alterations or propulsion plant modifications
- to address your vibration problem by combined analysis and measurement
Contact: globalvibration@gl-group.com
Local Structural Vibration Analysis
Local structures close to the propeller, main engine or thrusters might vibrate
excessively. To avoid such resonant vibration, it must be ensured that the
natural frequency of the structure does not coincide with the respective
exciting frequency. Typically, strong local vibration occurs at stiffened panel
structures (deck panels, tank walls) or as a coupled vibration of a subsystem
and its foundations. The subsystem can be either a structure itself (mast,
rudder, shaft bracket etc.) or a machinery and equipment part (gear box, fin
stabiliser, generator etc.). The natural frequencies of regular panel structures
can be calculated quickly by estimation formulae but for the analysis of coupled
vibration phenomenon the finite element method is called for.
GL offers to
- create higher crew and passenger comfort
- take preventive action for avoidance of vibration fatigue damage on structure, equipment and machinery
- resolve your local vibration problem by combining analysis and measurement
Contact: localvibration@gl-group.com
Shaft Vibration Analysis
The propulsion shafting of ships is exposed to fluctuating propeller forces,
imbalances and torque fluctuations induced by the main engine. Torsional,
lateral or axial shaft vibration might occur. If becoming excessive, increased
bearing and sealing wear and enhanced fatigue stresses will be created.
Moreover, shaft vibration might be transferred to the ship structure and thus
form the origin of increased noise and vibration levels. The choice of the
applicable analysis method and the suitable extent of the simulation model
depend on the individual case. E.g., whirling vibration must often be analysed
in combination with shaft alignment and axial vibrations can be computed
reliably only, if thrust bearing flexibility is considered. We will help you to
define a work scope tailored to your individual need.
GL offers to
- design shafting systems with enhanced reliability of couplings, bearings and sealings
- reduce the vibration loads acting on thrust bearings and reduction gears
- prevent fatigue cracks at shaft brackets and bearing foundations
- resolve your shaft vibration problem by combining analysis and measurement
Contact: shaftvibration@gl-group.com
