Accession Number : AD0665822

Title :   AMPLITUDE-DEPENDENT AND AMPLITUDE-INDEPENDENT INTERNAL FRICTION IN SODIUM CHLORIDE.

Descriptive Note : Interim technical rept. 1 Jul 65-1 Nov 66,

Corporate Author : WILKES COLL WILKES-BARRE PA RESEARCH AND GRADUATE CENTER

Personal Author(s) : Holden,S. J. ; Woronowicz,T. J. ; Heslin,T. M.

Report Date : DEC 1967

Pagination or Media Count : 85

Abstract : The high-amplitude decrement of pure NaCl was studied as a function of strain amplitude and time. Results show an asymmetric peak in internal friction versus maximum strain amplitude. Granato-Lucke plots yield a straight line only for the low-amplitude portion of the peak. Double-valued behavior of internal friction versus strain amplitude has sometimes been observed. Except for the case of double-valued behavior, internal friction was observed to increase and the dynamic Young's modulus to decrease with vibration time at all strain amplitudes. It is concluded that the Granato-Lucke theory can only partially explain these results. Some discrepancies between previously observed results are resolved if the internal friction is plotted versus the free decay strain amplitude. The anelastic relaxation peaks due to impurity-vacancy complexes were studied using Ca++ doping. An attempt was made to calculate values of the zero stress jump rates. Vibration along the <100> direction should excite three relaxation modes, resulting in three possible internal friction peaks. Along the <111> direction two modes are postulated resulting in two possible peaks. Experimentally, one sharp peak was found for the <111> orientation and one broad peak for the <100> direction. (Author)

Descriptors :   (*SODIUM CHLORIDE, *INTERNAL FRICTION), STRESSES, STRAIN(MECHANICS), RESONANT FREQUENCY, DISLOCATIONS, DOPING, CALCIUM, RELAXATION TIME

Subject Categories : Crystallography
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE