ASA 127th Meeting M.I.T. 1994 June 6-10

4aEA6. Pressurized dynamic analyzer: A device for measuring dynamic properties of materials over pressure and temperature.

Steven A. Africk

Mark D. Caplan

Jeffrey J. Hoefler

Atlantic Appl. Res. Corp., 4 A Street, Burlington, MA 01803

Many acoustic materials used in underwater applications have properties and hence performance which varies with depth pressure and temperature. A device has been built in which both the static deformation of a sample and its dynamic modulus and loss factor can be routinely measured up to 1000-psi pressure. This consists of a shake-table apparatus within a dedicated temperature-controlled pressure vessel. Pressurization is by air to avoid mechanical shorting paths. Transfer impedance measurements are made and the complex effective modulus of the sample---that which it would have if it were homogeneous---is inferred. Data are taken using a dual-channel analyzer under PC control, and analyzed by specially written Matlab software. Sample deformation is measured by an LVDT probe. Temperature control supports extrapolation of data in frequency by WLF scaling. Measured modulus and loss factor of two acoustic materials as a function of pressure show slightly different behavior. [Work supported by ONR.]