Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped Structures

The method of Modal Strain Energy (MSE) enables predictions of modal loss factors for vibrating systems from finite element analyses without evaluation of a complex-valued frequency response or a complex-valued frequency. While the method is simple, some error results; especially if the dissipative...

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Main Authors: Peter J. Torvik, Brian Runyon
Format: Article
Language:English
Published: Wiley 2007-01-01
Series:Shock and Vibration
Online Access:http://dx.doi.org/10.1155/2007/710498
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author Peter J. Torvik
Brian Runyon
author_facet Peter J. Torvik
Brian Runyon
author_sort Peter J. Torvik
collection DOAJ
description The method of Modal Strain Energy (MSE) enables predictions of modal loss factors for vibrating systems from finite element analyses without evaluation of a complex-valued frequency response or a complex-valued frequency. While the method is simple, some error results; especially if the dissipative material has the high loss factor characteristic of materials added to increase system damping. Several methods for reducing this error through modifications to MSE have been suggested. In this work, the exact loss factor for a simple mechanical system is found. The method of Modal Strain Energy (MSE) is then used to find the loss factor for that prototype system and errors are evaluated in terms of system parameters. Comparisons are also made to predictions with several modifications to MSE. A modification due to Rongong is found to provide significant improvement. The use of this modification together with MSE is shown to lead to lower and upper bounds for the system loss factor. As the prototype system is shown to be mechanically equivalent to constrained layer damping configurations, the findings are applicable to the analysis and design of optimized sandwich beams, plates, and damping tapes. Results are given for beams and plates with constrained layer treatments.
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spelling doaj-art-bb74d493184f43d0b27de525dedb0d0c2025-02-03T01:22:24ZengWileyShock and Vibration1070-96221875-92032007-01-0114533935310.1155/2007/710498Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped StructuresPeter J. Torvik0Brian Runyon1Air Force Institute of Technology, Universal Technology Incorporated, 1866 Winchester Road, Xenia, OH 45385, USAAFRL/PRTS, Wright-Patterson AFB, OH 45433, USAThe method of Modal Strain Energy (MSE) enables predictions of modal loss factors for vibrating systems from finite element analyses without evaluation of a complex-valued frequency response or a complex-valued frequency. While the method is simple, some error results; especially if the dissipative material has the high loss factor characteristic of materials added to increase system damping. Several methods for reducing this error through modifications to MSE have been suggested. In this work, the exact loss factor for a simple mechanical system is found. The method of Modal Strain Energy (MSE) is then used to find the loss factor for that prototype system and errors are evaluated in terms of system parameters. Comparisons are also made to predictions with several modifications to MSE. A modification due to Rongong is found to provide significant improvement. The use of this modification together with MSE is shown to lead to lower and upper bounds for the system loss factor. As the prototype system is shown to be mechanically equivalent to constrained layer damping configurations, the findings are applicable to the analysis and design of optimized sandwich beams, plates, and damping tapes. Results are given for beams and plates with constrained layer treatments.http://dx.doi.org/10.1155/2007/710498
spellingShingle Peter J. Torvik
Brian Runyon
Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped Structures
Shock and Vibration
title Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped Structures
title_full Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped Structures
title_fullStr Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped Structures
title_full_unstemmed Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped Structures
title_short Modifications to the Method of Modal Strain Energy for Improved Estimates of Loss Factors for Damped Structures
title_sort modifications to the method of modal strain energy for improved estimates of loss factors for damped structures
url http://dx.doi.org/10.1155/2007/710498
work_keys_str_mv AT peterjtorvik modificationstothemethodofmodalstrainenergyforimprovedestimatesoflossfactorsfordampedstructures
AT brianrunyon modificationstothemethodofmodalstrainenergyforimprovedestimatesoflossfactorsfordampedstructures