title: Dynamic acoustoelastic testing of weakly pre-loaded unconsolidated water-saturated glass beads.
abstract: Dynamic acoustoelastic testing is applied to weakly pre-loaded unconsolidated water-saturated glass beads. The gravitational acceleration produces, on the probed beads, a static stress of order 130 Pa, thus the granular medium is close to the jamming transition. A low-frequency (LF) acoustic wave gently disturbs the medium, inducing successively slight expansion and compaction of the granular packing expected to modulate the number of contacts between beads. Ultrasound (US) pulses are emitted simultaneously to dynamically detect the induced modification of the granular skeleton. US propagation velocity and attenuation both increase when the LF pressure increases. The quadratic nonlinear elastic parameter β, related to the pressure dependence of US propagation velocity, was measured in the range 60-530 if water-saturated glass beads are considered as an effective medium. A dynamic modification of US scattering induced by beads is proposed to modulate US attenuation. Complex hysteretic behaviors and tension-compression asymmetry are also observed and analyzed by time-domain and spectral analyses. Furthermore acoustic nonlinearities are measured in cases of quasi-static and dynamic variations of the LF wave amplitude, providing quantitatively similar acoustic nonlinearities but qualitatively different.
authors.affiliation: INSERM U930-CNRS ERL3106-Université François Rabelais UFR Médecine, 10 boulevard Tonnellé, 37000 Tours, France. renaud_gu@yahoo.fr
authors.forename: Guillaume
authors.initials: G
authors.lastname: Renaud
authors.forename: Samuel
authors.initials: S
authors.lastname: Callé
authors.forename: Marielle
authors.initials: M
authors.lastname: Defontaine
mesh_terms: D004548:Elasticity; D004867:Equipment Design; D005898:Glass; D006112:Gravitation; D006874:Hydrostatic Pressure; D016014:Linear Models; D009038:Motion; D017711:Nonlinear Dynamics; D013016:Sound; D013314:Stress, Mechanical; D013997:Time Factors; D014465:Ultrasonics / Q000295:instrumentation*; D014867:Water
chemical_list: D014867:Water