LAUSR

Landmine detection in gravel road beds, soil, or sand for some mines (constructed out of plastic) are difficult to detect using ground penetrating radar. In acoustic landmine detection, one would like to remotely detect a vibration profile across the surface of the soil (sand or gravel) due to the interaction between a large soil column and the localized elastic top plate. In an idealized laboratory experiment, the soil plate oscillator (SPO) apparatus models an idealization of an acoustic landmine detection experiment. The clamped circular acrylic plate (1/8 in. thick) models the top plate of a plastic buried mine while the soil column (350 g dry sifted masonry sand) supported by the plate models the burial depth. A constant current amplified sinusoidal chirp from a sweep spectrum analyzer drives two three inch diam speakers (placed above the column) generating airborne excitation. A laser Doppler vibrometer (LDV) measured the rms particle velocity at 15 scan locations across the 4.5 inch diameter soil surface in sweeps between 50 Hz and 1250 Hz. The LDV-microphone frequency response vs. scan position is used to extract a response profile at any individual frequency. These mixed mode shapes are compared for both in-phase and out-of-phase excitation.Landmine detection in gravel road beds, soil, or sand for some mines (constructed out of plastic) are difficult to detect using ground penetrating radar. In acoustic landmine detection, one would like to remotely detect a vibration profile across the surface of the soil (sand or gravel) due to the interaction between a large soil column and the localized elastic top plate. In an idealized laboratory experiment, the soil plate oscillator (SPO) apparatus models an idealization of an acoustic landmine detection experiment. The clamped circular acrylic plate (1/8 in. thick) models the top plate of a plastic buried mine while the soil column (350 g dry sifted masonry sand) supported by the plate models the burial depth. A constant current amplified sinusoidal chirp from a sweep spectrum analyzer drives two three inch diam speakers (placed above the column) generating airborne excitation. A laser Doppler vibrometer (LDV) measured the rms particle velocity at 15 scan locations across the 4.5 inch diameter soil s...