Systems and methods for generating ultrasonic waves, exciting special classes of ultrasonic transducers and ultrasonic devices for engineering measurements

An electromagnetic acoustic transducer (EMAT) based elastic wave measurement system for nondestructive testing and evaluation of a test object, the EMAT based elastic wave measurement system comprising:

• a receiving EMAT configured to receive an elastic wave when positioned proximate to the test object,
• the receiving EMAT further comprising:
• a plurality of alternating magnets having a like pole arrangement and in close proximity to one another and serially spaced apart,
• a conductor set comprising electrically conductive elements and adapted to receive a plurality of wave modes, at least a portion of the conductor set being positioned in an active region,
• wherein the active region is defined by areas between and under the plurality of like pole magnets;
• wherein the plurality of like pole magnets are adapted to be positioned so that the direction of magnetization in the magnets is substantially parallel to the test object and,
• wherein the receiving EMAT is configured to receive one or more of the following elastic waves in the test object and adjacent to the active region:
• a normal beam shear horizontal wave, an angle beam shear horizontal wave, a shear horizontal guided wave, an angle beam shear vertical wave, an angle beam longitudinal wave, a surface wave, a Rayleigh wave, a Lamb wave, an interfacial wave, and a pipe mode.

An electromagnetic acoustic transducer (EMAT) system for nondestructive testing and evaluation of a test object, the EMAT system comprising:

• a plurality of alternating magnets having a like pole arrangement and in close proximity to one another and serially spaced apart;
• a first conductor set comprising electrically conductive elements and adapted to provide a plurality of wave modes, a portion of the first conductor set being positioned in an active region;
• a second conductor set comprising electrically conductive elements, a portion of the second conductor set being positioned in the active region;
• wherein the active region is defined by areas between and under the plurality of like pole magnets;
• a first EMAT driver configured to provide current to the first conductor set;
• and
• a second EMAT driver configured to provide current to the second conductor set,
• wherein the plurality of like pole magnets are adapted to be positioned so that the direction of magnetization in the magnets is substantially parallel to the test object;
• and
• wherein the EMAT system is configured to generate at least two elastic waves simultaneously.

A method of elastic wave measurement for nondestructive testing and evaluation of a test object, the method comprising the steps of:

• positioning an electromagnetic acoustic transducer (EMAT) proximate the test object;
• the EMAT comprising:
• a plurality of alternating magnets having like pole arrangements and in close proximity to one another and serially spaced apart,
• a conductor set comprising electrically conductive elements and adapted to receive a plurality of wave modes, a portion of the conductor set being positioned in an active region,
• wherein the active region is defined by areas between and under the plurality of like pole magnets,
• wherein the plurality of like pole magnets are adapted to be positioned so that the direction of magnetization in the magnets is substantially parallel to the test object;
• generating an elastic wave such that the elastic wave propagates at least one of in and on the test object,
• detecting the elastic wave propagating at least one of in and on the test object via the EMAT, wherein the elastic wave is one or more of the following:
• a normal beam shear horizontal wave, an angle beam shear horizontal wave, a shear horizontal guided wave, an angle beam shear vertical wave, an angle beam longitudinal wave, a surface wave, a Rayleigh wave, a Lamb wave, an interfacial wave, and a pipe mode, and
• analyzing differences in elastic wave character between the elastic wave in the generating step and the elastic wave in the detecting step to evaluate the test object.

A method of elastic wave measurement for nondestructive testing and evaluation of a test object, the method comprising the steps of:

• positioning an electromagnetic acoustic transducer (EMAT) proximate to the test object;
• generating an elastic wave via the EMAT such that the elastic wave propagates at least one of in and on the test object, the EMAT comprising:
• a plurality of alternating magnets having a like pole arrangement, each magnet being in close proximity to one another and serially spaced apart,
• a conductor set comprising electrically conductive elements and adapted to generate a plurality of wave modes, a portion of the conductor set being positioned in an active region, and
• wherein the active region is defined by areas between and under the plurality of like pole magnets,
• wherein the plurality of like pole magnets are adapted to be positioned so that the direction of magnetization in the magnets is substantially parallel to the test object, and
• wherein the generated elastic wave is one or more of the following:
• a normal beam shear horizontal wave, an angle beam shear horizontal wave, a shear horizontal guided wave, an angle beam shear vertical wave, an angle beam longitudinal wave, a surface wave, a Rayleigh wave, a Lamb wave, an interfacial wave, and a pipe mode,
• detecting the elastic wave propagating at least one of in and on the test object;
• and
• analyzing differences in elastic wave character between the elastic wave in the generating step and the elastic wave in the detecting step to evaluate the test object.