Derek Stewart
 09:50 Sep271996 Acoustic Attenuation Hi! My name is Derek Stewart and I am a graduate student at the University of Virginia. I am working on a problem where I am modeling acoustic waves in tungsten. However, so far, I have been unable to find any information about the acoustic attenuation in tungsten. I know this panel is specializing in transducers, but since you are also experts in ultrasonics, I was wondering if any of you would possibly know the value or possible references to explore. Thanks ahead of time, Derek Derek Stewart das4k@virginia.edu

 09:29 Sep301996 Re: Acoustic Attenuation Tungsten is a highly attenuative, highly reflective material. The degree of attenuation depends on the grain structure. Because of the high density, the impedance of tungsten is one of the highest of all materials and it is about 100 g/cc^2 sec. Yosi : Hi! : My name is Derek Stewart and I am a graduate student : at the University of Virginia. I am working on a problem : where I am modeling acoustic waves in tungsten. However, : so far, I have been unable to find any information about : the acoustic attenuation in tungsten. I know this panel : is specializing in transducers, but since you are also : experts in ultrasonics, I was wondering if any of you : would possibly know the value or possible references : to explore. : Thanks ahead of time, : Derek : : Derek Stewart : das4k@virginia.edu

W. Grandia
 00:41 Oct011996 Re: Acoustic Attenuation I looked up the information for the acoustic parameters in Tungsten and found something in the book from Prof Gordon Kino: Acoustic Waves with subtitle: Devices, Imaging & Analog Processing; Prentice Hall ISBN 0130030473. Page 551. This is a table generated by Dr. Allen Selfridge. It states: V_{l} = 5.2 (km/s) V_{s} = 2.9 (km/s) Density_{mo} = 19.4 (kg/m^{3} x 10^{ 6}) Z_{l} = 101.0 (density x long. velocity) Z_{s} = 56.3 (density x shear velocity) s = 0.27 (dB/cm) The attenuation A = a/f^{2} dB. s ^{2}/m x 10^{ 15}) (No value of A at any frequency was given)Further more there are some Tungsten parameters given in "Ultrasonics, fundamentals , applications by Dale Ensminger., page 210, book ISBN: 0824776593 No attenuation information is given, however it states the following useful information: 1) Tungsten: Bar (c_{0}) = 4.60, Bulk (c_{B}) =5.18, Shear (c_{s} ) = 2.87, Dens=19.25, Characteristic impedance (rc_{B}) = 9.98, Poisson's ratio 0.28, 2) Tungsten annealed: Bar (c_{0}) = 4.62, Bulk (c_{B}) =5.22, c_{s}=2.89, Dens=19.30, Characteristic impedance (rc_{B}) = 10.07 3) Tungsten: Bar (c_{0}) = 4.31, Bulk (c_{B}) =5.46, c_{s}=2.62, Dens=19.10, Characteristic impedance =10.42 4) Tungsten, drawn: Bulk (c_{B}) =5.41, c_{s}=2.62, Dens =19.30, Characteristic impedance =10.44 5) Tungsten: (c_{B}) =5.17, c_{s}=2.62, Dens =19.30, Characteristic impedance =10.00, reference 24 The above information is probably not sufficient. Attenuation is influenced by absorption, grain structure, beam spreading, hysteresis and temperature. It is probably the best to make some simple measurements to derive the numbers for the specific application. In regards to attenuation of guided plate wave modes in Tungsten, the problem becomes very complex to calculate and again, it is probably best to measure it.
