The Journal of the Acoustical Society of Korea

The Acoustical Society of Korea (한국음향학회)
권호 표지

Measurement of Complex Modulus of Acoustic Materials by Using Transfer Function Method

  • Kim, Hyun-Sil (Acoustics Lab. Korea Institute of Machinery and Materials) ;
  • Kim, Jae-Seung (Acoustics Lab. Korea Institute of Machinery and Materials) ;
  • Kang, Hyun-Joo (Acoustics Lab. Korea Institute of Machinery and Materials) ;
  • Kim, Bong-Ki (Acoustics Lab. Korea Institute of Machinery and Materials) ;
  • Kim, Sang-Ryul (Acoustics Lab. Korea Institute of Machinery and Materials)
  • Published : 2002.03.01
Download PDF
⟨ Previous Next ⟩

Abstract

Two improvements are discussed in measurement of the complex Young's modulus of the acoustic materials by using the transfer function method. It is found that the accelerometer misalignment might result in the severe measurement error, particularly in high frequency range. The supporting structure is modified to attach the upper and lower accelerometers along the vertical axis. Secondly, the method fur solving the equation associated with wave model is described. The solution of the lumped mass-spring model is chosen as the starting value for low frequency range, while in the mid and high frequency, the solution to the previous frequency step is used as the initial values. Measurements are done for hard and soft rubber specimens. It is shown that the erroneous peaks in the transfer function, due to the measurement error, cause highly incorrect Young's modulus and loss factors.

Keywords

References

  1. L. F. Nielsen, N. J. Wismer, and S. Gade, 'An improved method for estimating the dynamic properties of materials,' Sound and Vibration, pp. 20-24, Feb, 2000
  2. Tae-Kil Ahn, Estimation of Complex Modulus for Viscoelastic Materials, Ph. D. Thesis, Dept. of Mechanical Engineering, KAIST, 1993
  3. Song Sim, A Method to determine Complex Young's Modulus and Poisson's Ratio of Viscoelastic Materials for FEM Applications, Ph. D. Thesis, Dept. of Mechanical Engineering, KAIST, 1991
  4. T. Pritz, 'Transfer function method for investigating the complex modulus of acoustic materials: spring-like specimen,' J. Sound and Vibration, vol. 72, no. 3, pp. 317-341, 1980 https://doi.org/10.1016/0022-460X(80)90380-6
  5. T. Pritz, 'Transfer function method for investigating the complex modulus of acoustic materials: rod-like specimen,' J. Sound and Vibration, vol. 81, no. 3, pp. 359-376, 1982 https://doi.org/10.1016/0022-460X(82)90245-0
  6. J. C. Snowdon, Vibration and Shock in Damped Mechanical Systems, John Wiley & Sons, Chap. 6, 1988
  7. J. L. Buchanan, 'Numerical solution for the dynamic moduli of a viscoelastic bar,' J. Acoust. Soc. Am., vol. 81, no. 6, pp. 1775-1786, 1987 https://doi.org/10.1121/1.394742