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Title
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The Absolute Value Modal Strain Energy Method
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Description
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The Modal Strain Energy (MSE) method has become a significant design tool in the last decade. The MSE method allows the approximate solution to a complex eigenvalue problem using the solution to a real eigenvalue problem and knowledge of element loss factors and the percentage of MSE contained in each element.
While the MSE method has been shown to be relatively accurate in many instances, particularly for design purposes, it can produce high errors even in simple cases with relatively low damping levels. This paper discusses a new MSE method which allows the approximate solution to complex eigenvalue problems while providing more accurate approximations.
The Absolute Value MSE (AVMSE) method incorporates the absolute value of the individual element impedances to form a real "stiffness" matrix. From the solution of the eigenvalue problem associated with the system mass matrix and this real "stiffness" matrix; approximate mode shapes, natural frequencies, and damping ratios may be obtained.
The new method provides greater accuracy than the standard MSE method in most instances, and more importantly provides conservative damping estimates while the standard method tend to overpredict damping ratios. The AVMSE provides more accurate results while remaining inexpensive to implement.
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Creator
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Morgenthaler, Daniel R.
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Publisher
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Wright-Patterson Air Force Base, OH : Wright Laboratory, Flight Dynamics Directorate, Air Force Systems Command
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Date
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1991
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Format
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1 online resource (16 pages) : ill.
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Type
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article
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Abstract
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The Modal Strain Energy (MSE) method has become a significant design tool in the last decade. The MSE method allows the approximate solution to a complex eigenvalue problem using the solution to a real eigenvalue problem and knowledge of element loss factors and the percentage of MSE contained in each element.
While the MSE method has been shown to be relatively accurate in many instances, particularly for design purposes, it can produce high errors even in simple cases with relatively low damping levels. This paper discusses a new MSE method which allows the approximate solution to complex eigenvalue problems while providing more accurate approximations.
The Absolute Value MSE (AVMSE) method incorporates the absolute value of the individual element impedances to form a real "stiffness" matrix. From the solution of the eigenvalue problem associated with the system mass matrix and this real "stiffness" matrix; approximate mode shapes, natural frequencies, and damping ratios may be obtained.
The new method provides greater accuracy than the standard MSE method in most instances, and more importantly provides conservative damping estimates while the standard method tend to overpredict damping ratios. The AVMSE provides more accurate results while remaining inexpensive to implement.
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Date Issued
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1991-08
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Extent
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16
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Corporate Author
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Martin Marietta Astronautics Group
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Laboratory
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Wright Laboratory
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Report Number
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WL-TR-91-3078 Volume II, pages FDB-1 to FDB-16
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DoD Project
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2401
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DoD Task
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240104
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Distribution Conflict
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No
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Index Abstract
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Contrails only
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Photo Quality
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Complete
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Distribution Classification
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1
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Report Availability
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Full text available
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Provenance
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University of Colorado Colorado Springs, Kraemer Family Library
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Identifier
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ADA241312
