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Mikaelsson Elmén, Pär
Publications (3 of 3) Show all publications
Mikaelsson Elmén, P., Andersson, T. & Olsson, M.Including deformation in a model for engine blockdynamics: measurement and prediction of vibration.
Open this publication in new window or tab >>Including deformation in a model for engine blockdynamics: measurement and prediction of vibration
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Internal combustion engines (ICE) are sources of vibration in many applications. Engine mounted components need to be designed with respect to fatigue, to withstand these vibrations. In order to compute an estimate of the fatigue life of a component, the vibration load needs to be known. A methodology that is based on a seven degree of freedom model to represent the engine block is proposed. By fitting measured accelerometer data to this model, acceleration levels in arbitrary positions and directions, related to the engine block, may be computed. Results presented for an engine vibration measurement show good agreement between measured and computed vibration levels. A measure to find erroneous accelerometer definitions is also proposed and exemplified through measurement results. The method also enables pointing out local dynamic phenomena at measurement points.

Keywords
engine, engine block vibrations, engine block twist, rigid body vibrations, vibration measurement, vibration estimation
National Category
Other Mechanical Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:kth:diva-220536 (URN)
Note

QC 20171229

Available from: 2017-12-22 Created: 2017-12-22 Last updated: 2017-12-29Bibliographically approved
Mikaelsson Elmén, P., Olsson, M. & Andersson, T.Inclusion of assumed bending and torsion modes for prediction of engine block vibrations.
Open this publication in new window or tab >>Inclusion of assumed bending and torsion modes for prediction of engine block vibrations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

For existing engine types, measured vibrations are commonly used as input to computations and shake rig tests. Accelerations are possible to compute in positions that have not been measured by fitting measured accelerometer data to a discretised engine block motion description. The computed accelerations can be used in fatigue risk estimation for engine components, mounted in new positions. In addition to the rigid body motion, engine block twist has previously successfully been included to better describe the engine block vibration. In the current paper, three additional deformation modes, of bending type, are suggested in order to describe engine block motions even better. The motion description is validated with an engine vibration measurement on a Scania inline six cylinder, heavy-duty diesel engine. An error measure for RMS vibration, summed for all sensors, is used to rank the studied deformation modes. In the studied frequency range, the most important deformation mode is the engine block twist. Including bending deformation increases the accuracy of the engine block vibration description but it also increases the demands on instrumentation.

Keywords
engine, engine block vibrations, engine block twist, engine block bending, rigid body vibrations, vibration measurement, vibration estimation, assumed modes, bending modes, torsion modes
National Category
Other Mechanical Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:kth:diva-220537 (URN)
Note

QC 20171229

Available from: 2017-12-22 Created: 2017-12-22 Last updated: 2017-12-29Bibliographically approved
Mikaelsson Elmén, P., Andersson, T. & Olsson, M.Modification of measured engine vibrations for addition or removal of engine mounted components.
Open this publication in new window or tab >>Modification of measured engine vibrations for addition or removal of engine mounted components
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Internal combustion engines are used in many applications. The same engine type may have different components mounted to it depending on the application. These engine mounted components need to be designed with respect to fatigue to withstand the engine vibrations. Measured engine vibrations are commonly used as input data for fatigue estimation. Some engine mounted components have themselves significant effect on the engine block vibrations. A method is presented on how measured engine vibration time signals can be modified for addition, or removal, of an engine mounted component. The dynamic characteristics of the component are here captured from measurements during engine operation but can also be extracted from a corresponding finite element model. Results of modification are presented for a heavy-duty inline, five cylinder diesel engine, with and without a 29 kg brake air compressor.

Keywords
engine, engine block vibration, engine block twist, vibration measurement, vibration estimation, rigid body vibrations, torsion modes, system modification, vibration modification
National Category
Other Mechanical Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:kth:diva-220539 (URN)
Note

QC 20171229

Available from: 2017-12-22 Created: 2017-12-22 Last updated: 2017-12-29Bibliographically approved
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