Patent ID: 6119804
Filing Date: 2000-09-19
Classification: G01V

Abstract:
A dynamic force transducer for generating horizontally oriented shear forces and motions at a surface of a solid medium for purposes of producing dynamic shear stresses and radiating associated horizontally polarized shear waves in said solid medium, comprising:a rigid coupling frame for direct contact with said surface of said solid medium, said coupling frame being in uninterrupted contact with said solid medium during vibrational operation of said dynamic force transducer;at least one pair of identical dynamic-force driver units mounted on said coupling frame to impart horizontally oriented dynamic forces having prescribed amplitude and time dependence to said coupling frame, said prescribed forces transferrable to said solid medium;at least one pair of identical compliant springs supporting each said pair of identical dynamic force driver units mounted on said coupling frame, compliances of each said pair of springs introducing different predetermined mechanical resonances when acting in combination with the masses of said supported pairs of identical driver units and said coupling frame when excitation energy is applied to said driver units;a means for exciting said dynamic force driver units in a manner to produce horizontally oriented forces on said coupling frame whereby one of said paired driver units imparts a horizontal pushing force and the second of the said paired driver units simultaneously imparts a horizontal pulling force equal to the pushing force, both of said forces being oriented to act along a common collinear horizontal direction; anda means for electrically exciting said paired dynamic force driver units in a manner which imparts either continuous or pulsed oscillatory forces to said coupling frame, said continuous or pulsed oscillatory forces being prescribed in amplitude and time dependence to produce corresponding prescribed seismic shear waves in said solid medium.