The ECERTA Project

The ability to analyse the influence of uncertainty in the structural model parameters is a vibrant research area. Uncertainty arises for example from the modelling of joints. A ground vibration test provides data on the vibratory response, which is then used to update key parameters in the structural model to better match the measurements. This is a crucial step in a flutter certification.

It is possible to perform this analysis in a stochastic manner. If multiple vibration tests, or tests on multiple structures are available, then the measurements form a probability distribution. If the parameters are assumed to have some distribution also then the mean and variance can be set to match the mean and variance in the measurements. This is called stochastic model updating.

Taking the model updating ideas one step further, methods can be used to propagate structural parameter distributions through to flutter speed distributions. Different methods are being investigated: Monte-Carlo simulation, first and second order perturbation analysis and interval analysis. Initial investigations have been based on linear aeroelastic methods. For CFD based analysis. the Schur complement framework for flutter calculation is powerful for this type of analysis.

Progress

• Developing perturbation methods for stochastic model updating- Journal paper
• propagation methods for linear aeroelastic analysis - Journal paper
• Developing interval model updating- Conference paper

Thesis

• Stochastic Finite Element Model Updating and its Application in Aeroelasticity

References

1. Haddad Khodaparast, H, Mottershead, J.E. and Friswell, M.I., Perturbation methods for the estimation of parameter variability in stochastic model updating, Mechanical Systems and Signal Processing, Volume 22, Issue 8, November 2008, Pages 1751-1773.
2. Haddad Khodaparast, H, Mottershead, J.E. and Badcock, K.J., Propagation of structural uncertainty to linear aeroelastic stability, Computers and Structures , Volume 88, Issue 3-4, February 2010, Pages 223-236.
3. Husain N.A. , Haddad Khodaparast H. , Snaylam A., James S., Dearden G., Ouyang H. Finite-element modelling and updating of laser spot weld joints in a top-hat structure for dynamic analysis , Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Volume 224, Issue 4, 2010, Pages 851-861.
4. Husain N.A. , Haddad Khodaparast H. , Ouyang H. FE Model Updating of Welded Structures for Identification of Defects , International Journal of Vehicle Noise and Vibration, Volume 6, Issue 2-3, 2010, Pages 163-175.
5. Haddad Khodaparast, H, Mottershead, J.E., Badcock, K.J. and Mares, C., Statistical Parameter Estimation from Modal Data using a Variable Transformation and Two Weighting Matrices, in proceeding of 1st International Conference on Uncertainty in Structural Dynamics, 11-13, 2007, University of Sheffield,Sheffield, UK.
6. Haddad Khodaparast, H, Mottershead, J.E., Efficient Methods in Stochastic Model Updating, in proceeding of International Conference on Noise and Vibration, Katholieke Universiteit Leuven, Leuven, Belgium, 15-17 September, ISMA 2008,Pages 1855-1870.
7. Haddad Khodaparast, H., Marques, S., Badcock, K.J. and Mottershead, J.E., Estimation of Flutter Boundaries in the Presence of Structural Uncertainty by Probabilistic and Fuzzy Methods,in proceeding of International Conference on Structural Engineering Dynamics, Ericeira, Portugal, 22-24 June 2009.
8. CFD Based Aeroelastic Stability Predictions Under the Influence of Structural Variability - SDM Paper 2009
9. Abu Husain, N., Snaylam, A., Haddad Khodaparast, H., James, S., Dearden, G. and Ouyang, H., FE Model Updating for Damage Detection : Application to a Welded Structure, Key Engineering Materials, Vols.413-414 (2009) pages 393-400.
10. Abu Husain, N., Haddad Khodaparast, H., Snaylam, A., James, S., Sharp, M., Dearden, G. and Ouyang, H., Modal Testing and Finite Element Model Updating of Laser Spot Welds , 7th International Conference on Modern Practice in Stress and Vibration Analysis, 8-10September 2009, Cambridge, U.K.
11. Husain N.A. , Haddad Khodaparast H. , Ouyang H. Parameter selection for stochastic uncertainty in dynamic models of simple and complicated structures, 10 th International Conference RASD 2010, Southampton, UK.
12. Husain N.A. , Haddad Khodaparast H. , Mottershead J.E., Ouyang H. Application of the perturbation method with parameter weighting matrix assignments for estimating variabilty in a set of nominally identical welded structures, Proceedings of the ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, July 12-14, 2010, Istanbul, Turkey, ESDA2010-24272
13. Haddad Khodaparast H., Mottershead J.E. and Badcock K.J., Interval model updating: method and application, in proceeding of International Conference on Noise and Vibration, Katholieke Universiteit Leuven, Leuven, Belgium, 20-22 September, ISMA-USD 2010,Pages 5277-5290.
14. Haddad Khodaparast, H, Mottershead, J.E. and Badcock, K.J., Interval model updating with irreducible uncertainty using the Kriging predictor, Mechanical Systems and Signal Processing, in press.

Contact