Patent ID: 6170336
Filing Date: 2001-01-09
Classification: G01N

Abstract:
A method for determining at least one resonant frequency of vibration of a cylindrical object using an electromagnetic acoustic transducer having at least one wire coil, the electromagnetic acoustic transducer inducing one of axial shear mode vibrations, torsional mode vibrations, radial mode vibrations, and plane strain mode vibrations in the cylindrical object, the method comprising the steps of:(a) applying an electrical excitation signal having a first frequency to the at least one wire coil of the electromagnetic acoustic transducer;(b) inducing a single mode of vibration in the cylindrical object in response to the electrical excitation signal;(c) sensing an impedance of the at least one wire coil of the electromagnetic acoustic transducer;(d) determining at least one resonant frequency of the cylindrical object based on the sensed impedance.