Abstract
Linear structural dynamic models are often used to support system design and qualification. Overall, linear models provide an efficient means for conducting design studies and augmenting test data by recovering un-instrumented or un-measurable quantities (e.g. stress). Nevertheless, the use of linear models often adds significant conservatism in design and qualification programs by failing to capture critical mechanisms for energy dissipation. Unfortunately, the use of explicit nonlinear models can require unacceptably large efforts in model development and experimental characterization to account for common nonlinearities such as frictional interfaces, macro-slip, and other complex material behavior. The computational requirements are also greater by orders of magnitude. Conversely, modal models are much more computationally efficient and experimentally have shown the ability to capture typical structural nonlinearity. Thus, this work will seek to use modal nonlinear identification techniques to improve the predictive capability of a finite element structural dynamics model.
Part I of this paper discusses the experimental aspects of this work. Linear natural frequencies, damping values, and mode shapes are extracted from low excitation level testing. Subsequently, the structure is excited with high level user-defined shaker inputs. The corresponding response data are modally filtered and fit with nonlinear elements to create the nonlinear pseudo-modal model. This is then used to simulate the measured response from a high level excitation experiment which utilized a different type of input. The nonlinear model is then employed in a reduced order, generalized structural dynamics model as discussed in Part II.
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy National Nuclear Security Administration under Contract DE-AC04-94AL85000.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Abbreviations
- a :
-
Time history of the triangle function
- c :
-
Damping coefficient
- f :
-
Frequency in cycles/sec
- f c :
-
Center frequency in cycles/sec
- F :
-
Force
- F r :
-
Restoring force
- G vf :
-
Shaker voltage to excitation force transfer function
- j:
-
Imaginary number variable
- k :
-
Stiffness coefficient
- q :
-
Modal degree of freedom
- t :
-
Time
- t r :
-
Rise time
- x :
-
Physical displacement degree of freedom
- v, V:
-
Shaker voltage, time domain and frequency domain, respectively
- ζ:
-
Modal damping ratio
- ω :
-
Frequency in radians per second
- \( \varphi_{dp}\) :
-
Drive point mode shape value
- H :
-
Frequency response function matrix
- P :
-
Modal response matrix
- \( \overset{-}{\mathbf{U}} \) :
-
Known restoring force vector
- \( \overset{-}{\boldsymbol{\Psi}} \) :
-
Modal filter vector
- D :
-
Subscript for desired
- flm :
-
Subscript for “first local minimum”
- \( \mathcal{F}\) :
-
Subscript for Fourier transform
- lin :
-
Subscript for linear
- n :
-
Subscript for natural
- nl :
-
Subscript for nonlinear
- u :
-
Subscript for updated
- +:
-
Moore-Penrose pseudo-inverse of a matrix
References
Mayes, R.L., Pacini, B.R, Roettgen, D. R.: A modal model to simulate typical structural dynamic nonlinearity. Presented at the 34th International Modal Analysis Conference, Orlando, FL, paper #121 January 2016
Hensley, Daniel P., Mayes, Randy L.: Extending SMAC to multiple references. Proceedings of the 24th International Modal Analysis Conference, Orlando, FL, pp. 220–230, January 2006
Mayes, R.L., Johansen, D.D.: A modal parameter extraction algorithm using best-fit reciprocal vectors. Proceedings of the 16th International Modal Analysis Conference, Santa Barbara, CA, pp. 517–521, February 1998
Gaëtan, K., Worden, K., Vakakisc, F.A., Golinval, J.C.: Past present, and future of nonlinear system identification in structural dynamics. Mech. Syst. Signal Process. 20, 505–592 (2006)
Acknowledgement
Notice: This manuscript has been authored by Sandia Corporation under Contract No. DE-AC04-94AL85000 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2017 The Society for Experimental Mechanics, Inc.
About this paper
Cite this paper
Pacini, B.R., Mayes, R.L., Owens, B.C., Schultz, R.A. (2017). Nonlinear Finite Element Model Updating, Part I: Experimental Techniques and Nonlinear Modal Model Parameter Extraction. In: Allen, M., Mayes, R., Rixen, D. (eds) Dynamics of Coupled Structures, Volume 4. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-319-54930-9_23
Download citation
DOI: https://doi.org/10.1007/978-3-319-54930-9_23
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-54929-3
Online ISBN: 978-3-319-54930-9
eBook Packages: EngineeringEngineering (R0)