Persistent Link:
http://hdl.handle.net/10150/193844
Title:
Model Reduction For a Restrained Deformable Body
Author:
Lin, Yi-shih
Issue Date:
2005
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Methods of component mode synthesis, such as Craig and Bampton reduction, are known to generally yield more accurate results in deformable multibody dynamics. The main shortcoming of those methods is that they are intuitively based. Recently Nikravesh developed a reduction method called mode condensation which is derived from the equations of motion and yields the same results as Craig and Bampton reduction. In this dissertation, it is proven that these two methods span the same column space; therefore, they should yield identical results. We propose that mode condensation provides an analytical justification for Craig and Bampton reduction. Test results suggest that Craig and Bampton reduction and mode condensation are appropriate for a broader range of applications because their column space matches up well with the conditions under which the deformable body is restrained. Although Guyan reduction preserves exact solutions for static problems, its applications shall be limited to low frequency excitation because of raised eigen-frequencies. Modal truncation is not recommended for use in multibody dynamic settings because it lacks the ability to receive forces and displacements at the moving boundary. Another issue addressed in this dissertation is the misconception that if mean axes are adopted as the moving reference frame, only free-free modes should be used for model reduction. It was not clear how a restrained deformable body with mean axes can be condensed properly. We have shown that the conventional (nodal-fixed) mode shapes can be used with mean axes as long as the transformation matrix has full rank and contains complete rigid-body mode shapes.
Type:
text; Electronic Dissertation
Keywords:
MODEL REDUCTION; Craig and Bampton reduction; mode condensation; DEFORMABLE BODY; mean axes; Multibody Dynamics
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Mechanical Engineering; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Nikravesh, Parviz E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleModel Reduction For a Restrained Deformable Bodyen_US
dc.creatorLin, Yi-shihen_US
dc.contributor.authorLin, Yi-shihen_US
dc.date.issued2005en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractMethods of component mode synthesis, such as Craig and Bampton reduction, are known to generally yield more accurate results in deformable multibody dynamics. The main shortcoming of those methods is that they are intuitively based. Recently Nikravesh developed a reduction method called mode condensation which is derived from the equations of motion and yields the same results as Craig and Bampton reduction. In this dissertation, it is proven that these two methods span the same column space; therefore, they should yield identical results. We propose that mode condensation provides an analytical justification for Craig and Bampton reduction. Test results suggest that Craig and Bampton reduction and mode condensation are appropriate for a broader range of applications because their column space matches up well with the conditions under which the deformable body is restrained. Although Guyan reduction preserves exact solutions for static problems, its applications shall be limited to low frequency excitation because of raised eigen-frequencies. Modal truncation is not recommended for use in multibody dynamic settings because it lacks the ability to receive forces and displacements at the moving boundary. Another issue addressed in this dissertation is the misconception that if mean axes are adopted as the moving reference frame, only free-free modes should be used for model reduction. It was not clear how a restrained deformable body with mean axes can be condensed properly. We have shown that the conventional (nodal-fixed) mode shapes can be used with mean axes as long as the transformation matrix has full rank and contains complete rigid-body mode shapes.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectMODEL REDUCTIONen_US
dc.subjectCraig and Bampton reductionen_US
dc.subjectmode condensationen_US
dc.subjectDEFORMABLE BODYen_US
dc.subjectmean axesen_US
dc.subjectMultibody Dynamicsen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMechanical Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairNikravesh, Parviz E.en_US
dc.contributor.committeememberNikravesh, Parviz E.en_US
dc.contributor.committeememberArabyan, Araen_US
dc.contributor.committeememberKamel, Hussein A.en_US
dc.contributor.committeememberCellier, Francois E.en_US
dc.identifier.proquest1412en_US
dc.identifier.oclc137355530en_US
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