Riga Technical University

1
Riga Technical University Institute of Materials
and Structures
Riga, Latvia
FINITE ELEMENT FREQUENCY-DEPENDENT DYNAMIC
ANALYSIS OF VISCOELASTIC COMPOSITE STRUCTURES
Evgeny Barkanov
FRAMEWORK6 CASSEM Lisbon,
Portugal Assembly meeting 22 July 2005
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Contents
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• Introduction
• Viscoelastic frequency-dependent damping model
• Finite element models
• Laminated composite finite element model
• Sandwich finite element model
• Finite element dynamic analysis
• Free vibration analysis
• Method of complex eigenvalues
• Energy method
• Frequency response analysis
• Transient response analysis
• Experimental dynamic analysis
• Numerical results

FRAMEWORK6 CASSEM Lisbon,
Portugal Assembly meeting 22 July 2005
3
Viscoelastic frequency-dependent damping model
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Damping material LD-400 applying as a damping
coating
Material properties
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Portugal Assembly meeting 22 July 2005
4
Laminated composite finite element model
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Portugal Assembly meeting 22 July 2005
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Sandwich finite element model
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Finite element dynamic analysis
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where
FRAMEWORK6 CASSEM Lisbon,
Portugal Assembly meeting 22 July 2005
7
Free vibration analysis
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Method of complex eigenvalues
Condition for termination of iteration process
Modal loss factors
FRAMEWORK6 CASSEM Lisbon,
Portugal Assembly meeting 22 July 2005
8
Free vibration analysis
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Energy method
Condition for termination of iteration process
Modal loss factors
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Portugal Assembly meeting 22 July 2005
9
Frequency response analysis
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Modal loss factors
Modal damping factors
Relationship
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Transient response analysis
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1st step
2nd step
3rd step
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Experimental dynamic analysis
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ISI-SYS laser vibrograph
POLYTEC laser vibrometer
Pulse technique
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Portugal Assembly meeting 22 July 2005
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Sandwich beam
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Damping material C-1002
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Dynamic characteristics of sandwich beam
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Solution convergence in the method of complex
eigenvalues
Frequency response of sandwich beam
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Portugal Assembly meeting 22 July 2005
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Transient response of sandwich beam
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Non-causal effect
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Material damping characteristics
Transient response of sandwich cantilever
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Conclusions
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NOTE
Unfortunately, the material data provided by the
manufacturers or testing laboratories do not
contain all necessary information to predict the
dynamic behaviour of viscoelastic composite
structures using different analysis tools.
FRAMEWORK6 CASSEM Lisbon,
Portugal Assembly meeting 22 July 2005