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Rod Lakes
University of Wisconsin
[Viscoelasticity research] [Demonstrations] [Viscoelasticity tutorial] [Viscoelastic Solids book] [Biomechanics]
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We use ultrasonic methodology as a tool for characterizing the elastic and viscoelastic properties of materials. The purposes are to better understand the relationship between structure and properties of complex heterogeneous materials including those of biological origin, and to guide the synthesis of new kinds of materials with extreme properties. For viscoelastic studies we also use broadband viscoelastic spectroscopy in which the same specimen can be examined at ultrasonic frequency up to 100 kHz or at audio or sub-audio frequency.

Selected research involving ultrasonics.

Lakes, R. S., "Viscoelastic measurement techniques", Review of Scientific Instruments, 75, 797-810, April (2004).
pdf

Wang, Y. C. and Lakes, R. S., "Resonant ultrasound spectroscopy in shear mode", Review of Scientific Instruments, 74, 1371-1373, Mar. (2003). download pdf

Lee, T., Lakes, R. S., and Lal, A., "Investigation of bovine bone by resonant ultrasound spectroscopy and transmission ultrasound", Biomechanics and Modeling in Mechanobiology, 1, 165-175, October (2002). (download pdf)

Lee, T. and Lakes, R. S., "Damping properties of lead metaniobate", IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 48, 48-52, Jan. (2001). download pdf

Lee, T., Lakes, R. S., Lal, A. , "Resonant ultrasound spectroscopy for measurement of mechanical damping: comparison with broadband viscoelastic spectroscopy", Rev. Sci. Instr. 71 (7) 2855-2861, July (2000). This article compares resonant ultrasound spectroscopy (RUS) and other resonant methods for the determination of viscoelastic properties such as damping. RUS scans from 50 kHz to 500 kHz were conducted on cubical specimens of several materials including brass, aluminum alloys and PMMA, a glassy polymer. Comparison of damping over the frequency ranges for broadband viscoelastic spectroscopy (BVS) and RUS for indium tin alloy in shear modes of deformation discloses a continuation of the tan delta power-law trend for ultrasonic frequencies up to 300 kHz. For PMMA, resonant peaks were sufficiently broad that higher modes in RUS began to overlap. Tan delta via RUS and BVS for PMMA agreed well in the frequency range where the methods overlap. RUS is capable of measuring tan delta as high as several percent at the fundamental frequency. Since higher modes are closely spaced, it is impractical to determine tan delta above 0.01 to 0.02 at frequencies other than the fundamental. download pdf

Resonant ultrasound spectrocopy setup Lakes, R. S., Yoon, H. S. and Katz, J. L., "Ultrasonic wave propagation and attenuation in wet bone," J. Biomed. Engng., 8 143-148 (1986). The propagation of ultrasonic longitudinal waves in bovine plexiform and wet human Haversian bone has been studied over the range 0.5 - 16 MHz. Little velocity dispersion was observed, in contrast to the results of earlier studies on dry bone. Large values of attenuation were observed.

Lakes, R. S., Yoon, H. S. and Katz, J. L., "Slow compressional wave propagation in wet human and bovine cortical bone", Science, 220 513-515, (1983). A slow compressional wave as well as the usual fast wave is observed in wet bone. The slow wave is attributed to stress-induced fluid motion in bone. Download pdf from jstor or here.


Selected teaching involving ultrasonics.
Biomechanics class, BME 315.
Advanced Mechanical Testing class, EMA611, including links to pages on nondestructive testing and resonant ultrasound spectroscopy.
Viscoelastic Solids class, EMA630, including ultrasonic attenuation and experimental methds.