Publication type: Conference paper
Type of review: Not specified
Title: Assessment of damping properties of large 2-stroke marine diesel engines
Authors: Secall Wimmel, Thomas
Müller, Dominic
Meier, Jürg
Conference details: International Conference on Engineering Vibration, Ljubljana, Slovenia, 07-10 September 2015
Issue Date: 2015
Language: English
Subjects: Vibration Simulation; Modal Damping Ratio; Eigenfrequency; Mode Shape
Subject (DDC): 620: Engineering
Abstract: When simulating the vibration behaviour of large 2-stroke marine diesel engines the damping properties are an important parameter to be considered. Simulations only allow determining realistic vibration amplitudes if the engine’s damping characteristic is known. Modal damping ratios of reciprocating engines vary depending on which parts of the engine interact during oscillation and on how energy is dissipated while vibrating. Therefore different damping ratios can be expected for different engine mode shapes. For determining typical modal damping ratios of a diesel engine a methodology for an automated analysis of vibration measurement data was developed: After identifying N resonance peaks in a measured vibration spectrum a spectral curve corresponding to a simple mass-spring-damper system with N degrees of freedom is automatically fitted onto the measured curve by parameter optimization. At the end of this iterative process the damping properties of the substituting mass-spring-damper-system, whose curve adjusts most precisely to the measured spectrum, are attributed to the measured resonances. In addition to determining modal damping ratios and eigenfrequencies the procedure allows separating overlapping resonance peaks. The analysis process was applied on vibration measurement results of a series of different marine diesel engines and characteristic modal damping ratios could be determined for the engine’s principal mode shapes. Considering the determined modal damping properties when performing forced response simulations of the engine by modal superposition in the frequency domain allowed to achieve a higher accuracy in the calculated vibration amplitudes.
Fulltext version: Published version
License (according to publishing contract): Licence according to publishing contract
Departement: School of Engineering
Organisational Unit: Institute of Mechanical Systems (IMES)
Appears in collections:Publikationen School of Engineering

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