Skip to main content
SpringerLink
Log in

Scaling Mode Shapes in Output-Only Systems by a Consecutive Mass Change Method

  • Published:
Experimental Mechanics Aims and scope Submit manuscript

Abstract

In operational modal analysis (OMA) mode shapes can be obtained only with arbitrary normalization. There are many applications where mass normalized mode shapes are required, such as response prediction and stress analysis. A method to scale the mode shapes in OMA is to modify the dynamic behaviour of the structure by adding masses and then to use the modal parameters of both the original and modified structure. Several mass change methods have been proposed in recent years for estimating the scaling factors, where a distributed array of added masses are needed to obtain good results. In this work a new mass change approach based on performing several individual mass changes is presented. This approach requires only a small number of masses that are located at different points in each individual experiment. The results of the individual tests are then combined to estimate the scaling factors. The approach is developed and validated by measurements carried out on a 15-tonne prestressed concrete slab strip and a steel cantilever beam. The results show that a good accuracy can be obtained by this method when a proper mass change strategy is used.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7

Similar content being viewed by others

References

  1. Cantieni R (2005) Experimental methods used in system identification of civil engineering structures. In: Proceedings of the International Operational Modal Analysis Conference(IOMAC), pp 249–260

  2. Cunha A, Caetano E (2005) From input-output to output-only modal identification of civil engineering. In: Proceedings of the International Operational Modal Analysis Conference(IOMAC), pp 11–27

  3. Brincker R, Ventura C, Andersen P (2003) Why output-only modal testing is a desirable tool for a wide range of practical applications. In: Proceedings of the International Modal Analysis Conference(IMAC-XXI), paper 265

  4. Møller N, Brincker R, Herlufsen H, Andersen P (2001) Modal testing of mechanical structures subject to operational excitation forces. In: Proceedings of the 19th International Modal Analysis Conference(IMAC-XXI), pp 262–269

  5. Brincker R, Andersen P, Møller N, Herlufsen H (2000) Output only testing of a car body subject to engine excitation. In: Proceedings of the 18th International Modal Analysis Conference(IMAC-XVIII), pp 786–792

  6. Magalhaes F, Caetano E, Cunha A (2008) Online identification of the modal parameters of a long span archbridge. Mechanical Systems and Signal Processing

  7. Magalhaes F, Cunha A, Caetano E (2008) Operational modal analysis and finite element model correlation of the braga stadium suspended roof. Engineering Structures (30):1688–1698

  8. Parloo E, Guillaume P, Anthonis J, Heylen W, Swevers N (2003) Modelling of sprayer boom dynamics by means of maximum likelihood identification techniques, part1: a comparison of input–output and output-only modal testing. Biosyst Eng 85(2):163–171

    Article  Google Scholar 

  9. Fernández P, Aenlle ML, Brincker R, Canteli AF (2009) Artificial excitation in operational modal analysis. In: Proc. of the International Modal Analysis Conference (IOMAC) III (0):643–650

  10. Aenlle ML, Brincker R, Canteli AF (2005) Some methods to determine scaled mode shapes in natural input modal analysis. In: Proc. of the International Modal Analysis Conference (IMAC-XXIII)

  11. Khatibi MM, Ashory MR, Malekjafarian A (2009) Scaling of mode shapes using mass-stiffness change method. In: Proc. of the International Operational Modal Analysis Conference (IOMAC) III, pp 699–706

  12. Parloo E, Verboven P, Cuillame P, Overmeire MV (2001) Sensitivity-based mass normalization of mode shape estimates from output-only data. In: Proc. Int. Conf. on Structural System Identification, pp 627–636

  13. Parloo E, Cauberghe B, Benedettini F, Alaggio R, Guillaume P (2005) Sensitivity-based operational mode shape normalisation: application to a bridge. Mech Syst Signal Process (19):45–55

  14. Parloo E, Guillaume P, Anthonis J, Heylen W, Swevers N (2003) Modelling o fsprayer boom dynamics by means of maximum likelihood identification techniques, part 2: sensitivity-based mode shape normalisation. Biosyst Eng 85(2):291–298

    Article  Google Scholar 

  15. Brincker R, Andersen P (2003) A way of getting scaled mode shapes in output only modal analysis. In: Proc. of the International Modal Analysis Conference (IMAC-XXI)

  16. Aenlle ML, Brincker R, Canteli AF, Villa LM (2005) Scaling factor estimation by the mass change method. In: Proc. of the International Operational Modal Analysis Conference (IOMAC)

  17. Bernal D (2004) Modal scaling from known mass perturbation. J Eng Mech 130(9):1083

    Article  Google Scholar 

  18. López-Aenlle M, Fernández P, Brincker R, Fernández-Canteli A (2009) Scaling factor estimation using an optimized mass-change strategy. Mechanical Systems and Signal Processing

  19. Fernández P, Reynolds P, López-Aenlle M (2010) Experimental evaluation of mass change approaches for scaling factors estimation. In: Proc. of the International Modal Analysis Conference (IMAC-XXVIII)

  20. Aenlle ML, Brincker R, Fernández P, Canteli AF (2007) Scaling factor estimation using a optimized mass change strategy. part 1: theory. In: Proc. of the International Operational Modal Analysis Conference (IOMAC) II

  21. Herlfunsen H, Andersen P, Gade S, Møller N (2005) Identification techniques for operational modal analysis—an overview and practical experiencies. In: Proc. of the International Operational Modal Analysis Conference (IOMAC)

  22. Brincker R, Andersen P, Jacobsen NJ (2007) Automated frequency domain decomposition for operational modal analysis. In: Proceedings of the 25th International Modal Analysis Conference(IMAC-XXV)

  23. Brincker R, Zhang L-M, Anderson P (2000) Modal identification from ambient response using frequency domain decomposition. In: Proc. of the 18th International Modal Analysis Conference (IMAC-XVIII)

  24. Peeters B, De Roeck G (2001) Stochastic system identification for operational modal analysis: a review. J Dyn Syst Meas Control-Trans of the ASME 4(123):659–667

    Article  Google Scholar 

  25. Van Overschee P, De Moor B (1996) Subspace identification for linear systems: theory, implementation & applications. Kluwer Publishers, Dordrecht, Netherlands

    MATH  Google Scholar 

  26. Brincker R, Andersen P (2006) Understanding stochastic subspace identification. In: Proceedings of International Modal Analysis Conference (IMAC-XXIV)

  27. Ewins DJ (1984) Modal testing: theory and practice. Research Studies Press LTD and Wiley

Download references

Acknowledgements

The authors would like to acknowledge the economic support given by the Spanish Ministry of Education through the projects BIA2005-07802-C02-02 and BIA2008-06816-C02-01 and the European Social Fund. Special thanks also go to Dr Donald Nyawako from the University of Sheffield for his support in the experimental part of this work.

Author information

Authors and Affiliations

  1. Department of Construction and Manufacturing Engineering, The University of Oviedo, Campus de Gijón, Zona Oeste, Edificio 7., 33203, Gijón, Spain

    P. Fernández & M. López-Aenlle

  2. Department of Civil and Structural Engineering, The University of Sheffield, Sir Frederick Mappin Building, Mappin Street, Sheffield, S1 3JD, UK

    P. Reynolds (SEM member)

  3. Full Scale Dynamics Limited, Sheffield Bioincubator, 40 Leavygreave Road, Sheffield, S3 7RD, UK

    P. Reynolds (SEM member)

Authors
  1. P. Fernández
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. P. Reynolds
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. M. López-Aenlle
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to P. Fernández.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Fernández, P., Reynolds, P. & López-Aenlle, M. Scaling Mode Shapes in Output-Only Systems by a Consecutive Mass Change Method. Exp Mech 51, 995–1005 (2011). https://doi.org/10.1007/s11340-010-9400-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11340-010-9400-0

Keywords

Search

Navigation