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Official Journal of the Japan Wood Research Society

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A statistical algorithm for comparing mode shapes of vibration testing before and after damage in timbers

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Abstract

Instances of local damage in timber such as knots, decay, and cracks can be translated into a reduction of service life due to mechanical and environmental loadings. In wood construction, it is very important to evaluate the weakest location and to detect damage at the earliest possible stage to avoid future catastrophic failure. In this study, modal testing was used on wood beams to generate the first two mode shapes. A novel statistical algorithm was proposed to extract a damage indicator by computing mode shapes of vibration testing before and after damage in timbers. The different damage severities, damage locations, and damage counts were simulated by removing mass from intact beams to verify the algorithm. The results showed that the proposed statistical algorithm is effective and suitable for the designed damage scenarios. It is reliable for the detection and location of local damage of different severities, location, and number. The peak values of the damage indicators computed from the first two mode shapes were sensitive to different damage severities and locations. They were also reliable for the detection of multiple cases of damage.

References

  1. 1.

    Yang XY, Ishimaru Y, Iida I, Urakami H (2002) Application of modal analysis by transfer function to nondestructive testing of wood I: determination of localized defects in wood by the shape of the flexural vibration wave. J Wood Sci 48:283–288

  2. 2.

    Hu YC, Nakao T, Nakai T, Gu JY, Wang FH (2005) Dynamic properties of three types of wood-based composites. J Wood Sci 51:7–12

  3. 3.

    Hu YC, Nakao T, Nakai T, Gu JY, Wang FH (2005) Vibration properties of wood plastic plywood. J Wood Sci 51:13–17

  4. 4.

    Kubojima Y, Ohta M, Okano T (2000) Vibrational properties of heat treated green wood. J Wood Sci 46:63–68

  5. 5.

    Guan HY (2002) Dynamic properties of wood in the moisture content region above the fiber saturation point. PhD dissertation, United Graduate School of Agriculture, Tottori University

  6. 6.

    Dong YK (1996) Dynamic properties for in-plane inhomogeneous wood-based materials. PhD dissertation, United Graduate School of Agriculture, Tottori University

  7. 7.

    Naki T, Hamatake M, Nakao T (2004) Relationship between piezoelectric behavior and the stress-strain curve of wood under combined compression and vibration stresses. J Wood Sci 50:97–99

  8. 8.

    Obataya E, Minato K, Tomita B (2001) Influence of moisture content on the vibrational properties of hematoxylin-impregnated wood. J Wood Sci 47:317–321

  9. 9.

    Xu H, Tanaka C, Nakao T, Yoshinobu M, Katayama H (1998) Evaluation of rolling shear strength of plywood by flexural vibration method. J Wood Sci 44:147–151

  10. 10.

    Yang XY, Amano T, Ishimaru Y, Iida I (2003) Application of modal analysis by transfer function to nondestructive testing of wood II: modulus of elasticity evaluation of sections of differing quality in a wooden beam by the curvature of the flexural vibration wave. J Wood Sci 49:140–144

  11. 11.

    Yang XY, Ishimaru Y, Urakami H (2001) Application of modal analysis by transfer function to nondestructive test of wood I. The determination of localized defects in wood by the shape of flexural vibration wave. J Wood Sci 47:304–310

  12. 12.

    Yang XY, Amano T, Ishimaru Y, Iida I (2001) Application of modal analysis by the transfer function on nondestructive test of wood II. Elasticity evaluation of different quality part within wooden beam by the curvature on flexural vibration wave. Mokuzai Gakkaishi 47:412–ss419

  13. 13.

    Yang XY, Ishimaru Y, Iida I (2002) Application of modal analysis by the transfer function to nondestructive testing of wood III: detection of knots and estimation of elastic modulus distribution in wood by the curvature ratio of the flexural vibration wave shape. Mokuzai Gakkaishi 48:16–22

  14. 14.

    Chui YH (1991) Simultaneous evaluation of bending and shear moduli of wood and the influence of knots on these parameters. Wood Sci Technol 25:125–134

  15. 15.

    Kenneth GM (1995) Vibration testing: theory and practice. Wiley, New York, pp 132–134

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Correspondence to Muhammad T. Afzal.

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Hu, C., Afzal, M.T. A statistical algorithm for comparing mode shapes of vibration testing before and after damage in timbers. J Wood Sci 52, 348–352 (2006) doi:10.1007/s10086-005-0769-9

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Key words

  • Damage detection
  • Mode shape
  • Timber
  • Nondestructive test