Variable frequency pulsed phase-locked loop method for measuring material nonlinearityThe design of a pressure vessel with an isothermal volume to measure changes in the natural velocities of material continuously over a wide temperature range is reported. Highly sensitive pulsed phase-locked loop technology is used to measure the natural velocity of fatigued aluminum 2024-T4 as a function of pressure at different temperatures. Second derivative variations with respect to pressure and temperature are found to exhibit order-of-magnitude changes at a gauge pressure near 950 kPa at room temperature. This indicates a significant change in certain combinations of second-order and higher-order elastic constants at relatively low pressures. Fractional frequency change as a function of applied pressure for aluminum 2024-T4 with fatigue damage is illustrated.
Document ID
19930035678
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Yost, William T. (NASA Langley Research Center Hampton, VA, United States)
Cantrell, John H. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1992
Publication Information
Publication: In: Review of progress in quantitative nondestructive evaluation. Vol. 11B; Proceedings of the 18th Annual Review, Brunswick, ME, July 28-Aug. 2, 1991 (A93-19582 06-38)