Recent work in the group has shown that measurements of the changes in the propagation of guided waves along a bar when the bar is 'dipped' into a surrounding material may be used to estimate the acoustic properties of the embedding medium. The technique has been used successfully to measure the viscosity of liquids and to obtain the longitudinal and shear velocities of the soil surrounding water pipes. At present, it is only possible to obtain the velocities of the material. If a material model that connects velocity and attenuation is known to be valid (as in, for example, the case of a viscous liquid), the material is completely characterised by this measurement. However, in many cases an appropriate model is not available and the current project aims to obtain values of the bulk velocity and attenuation of the surrounding medium direct from the guided wave measurements.

A 'Dipstick' sensor for material property measurement

References

T Vogt, M J S Lowe, P Cawley, "The scattering of guided waves in partly embedded cylindrical structures", J.Acoust. Soc. Am., vol 113, pp. 1258-1272, 2003.

T Vogt, M J S Lowe, P Cawley, "Measurement of the material properties of viscous liquids using ultrasonic guided waves", IEEE Trans. Ultrasonics, Ferroelectrics and Frequency Control, vol. 51, pp. 737-747, 2004.

R S Long, T Vogt, M J S Lowe, P Cawley, "Measurement of acoustic properties of near-surface soils using an ultrasonic waveguide", Geophysics, vol 69, pp460-465, 2004.

S H Pu, F Cegla, M Drozdz, N Buenfeld, M J S Lowe, P Cawley, "Concrete cure monitoring using an ultrasonic waveguide", Insight, vol 46, pp. 350-354, 2004.

F B Cegla, M J S Lowe, P Cawley, "Material property measurement using the quasi-Scholte mode - a waveguide sensor", J.Acoust. Soc. Am., vol. 117, pp. 1098-1107, 2005.

F B Cegla, P Cawley, M J S lowe, "Fluid bulk velocity and attenuation measurements in non-Newtonian liquids using a dipstick sensor", Meast Sci Technol, vol. 17, 264-274, 2006.

Z Fan, MJS Lowe, M Castaings, C Bacon, "Torsional Waves Propagation Along a Waveguide of Arbitrary Cross-section Immersed in a Perfect Fluid", J. Acoust. Soc. Am., vol 124, 2002-2010, 2008.