HR: 1330h
AN: T42A-0276    [PDF]
TI: Investigation Of The Transition To Nonlinear Acoustics In Driven Rods
AU: * Pasqualini, D
EM: dondy@lanl.gov
AF: Los Alamos National Laboratory Earth and Environmental Sciences, EES-11, MS D443, Los Alamos, NM 8745 United States
AU: Jim, T
EM: tencate@lanl.gov
AF: Los Alamos National Laboratory Earth and Environmental Sciences, EES-11, MS D443, Los Alamos, NM 8745 United States
AU: Habib, S
EM: habib@lanl.gov
AF: Los Alamos National Laboratory Theretical Division, MS B285, Los Alamos, NM 8745 United States
AU: Heitmann, K
EM: heitmann@lanl.gov
AF: Los Alamos National Laboratory Theretical Division, MS B285, Los Alamos, NM 8745 United States
AU: Johnson, P
EM: paj@lanl.gov
AF: Los Alamos National Laboratory Earth and Environmental Sciences, EES-11, MS D443, Los Alamos, NM 8745 United States
AB: We have investigated the response of rods of various materials as a function of the driving frequency and drive amplitude near resonance. For linear materials one expects no change in resonance frequency as a function of the drive amplitude, while classical (Landau) nonlinearity manifests itself as a softening (or hardening) in the resonance frequency proportional to the square of the driving amplitude. A softening in the resonance frequency directly proportional to the magnitude of the drive is known to exist in diverse materials, both damaged and undamaged. Our study of multiple materials, carried out over a broad range of internal strains, was aimed at unambiguously establishing the domains of internal strain where these different phenomena exist. As a function of internal strain, our results are consistent with an initial harmonic behavior, followed by the onset of classical nonlinearity, and finally by a frequency shift linearly proportional to the drive amplitude.
DE: 3210 Modeling
DE: 3220 Nonlinear dynamics
DE: 3902 Creep and deformation
DE: 3909 Elasticity and anelasticity
DE: 5102 Acoustic properties
SC: Tectonophysics [T]
MN: 2003 Fall Meeting