Government of the United States of America, As Represented by the Secretary of Commerce

Rockwell International Corporation

Other

Iowa State University Research Foundation, Inc.

Magnasonics, Inc.

George A Alers

Robert B Thompson

Ward L Johnson

Bertram A Auld

Leigh R Burns, Jr

Alfred V Clark

Thanh Nguyen

Christopher Hehman

Kevin Coakley

Carmine F Vasile

Rahmat A Shoureshi

Samuel J Wormley

Michael T Chenowith

Daniel T MacLauchlan

Paul K Davidson

Bert A Auld

Marion A Tennison

A method and apparatus for measurement of stress in a specimen utilizing a motorized electromagnetic acoustic transducer (EMAT). Stress causes a rotation of the pure-mode polarization directions of SH-waves and a change in the phase of waves polarized along these certain directions. The method utilizes a rotating small-aperture EMAT, connected to a processor, to measure phase and amplitude data as a function of angle. The EMAT is placed on a workpiece at the location where the stress is to be measured. The acoustic birefringence B is determined from the normalized difference of these phases. From these data, an algorithm calculates values of B and &PHgr;. The workpiece is then stressed or its stress state is changed. The values are measured again at the same location. Stress is determined from the change in B and &PHgr;.

Ultrasonic strain gage using a motorized electromagnetic acoustic transducer

The method of the invention identifies damage to an in-service conductor associated with the delivery (transmission and distribution) of electric power. Electro-magnetic acoustic energy is generated in an in-service conductor associated with the delivery of electric power. Corresponding return electro-magnetic acoustic energy is then measured. Features are then extracted from the return electro-magnetic acoustic energy to characterize damage to the in-service conductor. The features may be extracted through a variety of signal processing techniques, such as wavelet signal processing. The extracted features may be classified using a neural network, fuzzy logic, or a combination of both.

Apparatus and method for utilizing electromagnetic acoustic transducers to non-destructively analyze in-service conductive materials

A method for measurement of stress in a specimen utilizing a motorized electromagnetic acoustic transducer (EMAT). Stress causes a rotation of the pure-mode polarization directions of SH-waves and a change in the phase of waves polarized along these certain directions. The method utilizes a rotating small-aperture EMAT, connected to a processor, to measure phase and amplitude data as a function of angle. The EMAT is placed on a workpiece at the location where the stress is to be measured. The acoustic birefringence B is determined from the normalized difference of these phases. From these data, an algorithm calculates values of B. and &phgr;. The workpiece is then stressed or its stress state is changed. The values are measured again at the same location. Stress is determined from the change in B and &phgr;.

An electromagnetic acoustic transducer for inducing and sensing vibrations in a cylindrical object and methods of using an electromagnetic acoustic transducer to determine resonant frequencies and physical properties of cylindrical objects. The electromagnetic acoustic transducers produce specific modes of vibration in cylindrical objects including axial shear vibrations, torsional vibrations, radial vibrations and plane strain vibrations. The methods of determining physical properties of a cylindrical objects include comparing sensed resonant frequencies of the cylindrical object to known relationships between resonant frequency and the physical properties of interest. The methods can be used to determine the temperature, dimensions, elastic constants, and damping coefficients of cylindrical objects, the magnitude of a load applied to a cylindrical object, or the texture or grain orientation of the material forming a cylindrical object.

Electromagnetic acoustic transducer and methods of determining physical properties of cylindrical bodies using an electromagnetic acoustic transducer

An electromagnetic acoustic transducer for inducing and sensing vibrations n a cylindrical object and methods of using an electromagnetic acoustic transducer to determine resonant frequencies and physical properties of cylindrical objects. The electromagnetic acoustic transducers produce specific modes of vibration in cylindrical objects including axial shear vibrations. The electromagnetic acoustic transducers are used to determine the temperature, dimensions, elastic constants, and damping coefficients of cylindrical objects, the magnitude of a load applied to a cylindrical object, or the texture or grain orientation of the material forming a cylindrical object.

Electromagnetic acoustic transducer and methods of determining physical

A force sensor including a cylindrical body having a central section and two distal sections wherein selected acoustic resonant modes are trapped in the central section and decays exponentially in the distal sections. An electromechanical acoustic transducer (EMAT) can be used to excite and detect the selected resonant modes in the central section. Force applied to the distal sections, including axial stress and torque, alter the resonant frequencies of the selected modes.

Acoustic resonator for measuring force

Apparatus and method for nondestructive evaluation of butt welds. The present invention in its broadest form includes an apparatus and method for detecting flaws in butt welds in steel sheets using horizontal shear ultrasonic waves generated on the surface thereof. Observation of reflected waves having amplitude greater than a chosen value signals the presence of significant flaw. To achieve this objective, the present apparatus detects only reflected horizontal shear waves; other modes are electronically removed using bandpass filters, since they occur at different frequencies. The invention may therefore be used in the presence of surface structures such as clamps and the like, and in the presence of surface nonuniformities in the vicinity of the weld, thereby permitting on-line flaw detection steel mill environment without interfering with the line output. The ultrasonic waves are generated and received by a pair of electromagnetic acoustical transducers having magnetic fields which are oriented 40-65 degrees from the direction of the transmitted and received waves.

Apparatus and method for nondestructive evaluation of butt welds

The system for field measurement of texture, stress and related material properties such as formability parameters using ultrasonic velocity measurements through crystalline plate or sheet. Electromagnetic acoustic transducers are utilized to generate, transmit, and receive ultrasonic bursts through the plate at different angular orientations with respect to the plane of the plate. Two of the transducers are driven in series when generating the ultrasonic bursts. Time measurements between transmission and reception of the bursts are precisely derived and converted into velocities. Information regarding stress, texture, and other related material properties such as formability parameters can be derived from these velocity measurements. The system is adjustable to be used for both ferrous and nonferrous crystalline plate. Alteration of the types of ultrasonic waves utilized, and the methods of generating the waves allows different properties such as texture and stress to be derived.

Means and method for ultrasonic measurement of material properties

A noncontact ultrasonic transducer for studying the acoustic properties of a metal workpiece includes a generally planar magnetizing coil positioned above the surface of the workpiece, and a generally planar eddy current coil between the magnetizing coil and the workpiece. When a large current is passed through the magnetizing coil, a large magnetic field is applied to the near-surface regions of the workpiece. The eddy current coil can then be operated as a transmitter by passing an alternating current therethrough to excite ultrasonic waves in the surface of the workpiece, or operated as a passive receiver to sense ultrasonic waves in the surface by measuring the output signal. The geometries of the two coils can be varied widely to be effective for different types of ultrasonic waves. The coils are preferably packaged in a housing which does not interfere with their operation, but protects them from a variety of adverse environmental conditions.

Electromagnetic acoustic transducer

Disclosed is a nondestructive test device for detecting a flaw proximate to a welded seam in a pipe, including an electromagnetic acoustic transmitting transducer for generating a horizontally polarized shear wave in the wall of the pipe, a high frequency generator operatively connected to the transmitting transducer for energizing the transducer, an electromagnetic acoustic receiving transducer for responding to a horizontally polarized shear wave within the wall, an amplifier operatively connected to the receiving transducer for boosting the response signal of the transducer, and an indicating instrument for receiving and displaying the amplified response signal. In the test method disclosed, a horizontally polarized shear wave is generated in the wall, the pipe is monitored to detect a reflected horizontally polarized shear wave, and a time-dependent representation of the amplitude of the reflected wave is displayed. The wave generating, monitoring, and displaying steps are repeated along a length of the pipe to provide a comprehesive flaw inspection of that length of the pipe. The times of arrival of the generated and reflected waves are correlated to determine the circumferential position of the flaw.

Nondestructive testing utilizing horizontally polarized shear waves

An electromagnetic transducer is provided for ultrasonically inspecting conductive material as the material moves relative to the transducer. A coil is positioned in the field created by a magnet so that the conductors of the coil are transverse to the magnetic field. The coil is located predominately near the leading side of the magnet where flux is concentrated as the magnet and material move toward each other.

Electromagnetic transducer

A method and device which are suitable for the in-place inspection of pipelines are provided. A completely self-contained, mobile inspection station is placed inside a pipeline. The station runs through the pipe and transmits Lamb waves within the pipe wall, receives reflected and transmitted portions of the waves, and records the amplitude and phase of the received waves. The recorded information is analyzed to determine the location and nature of discontinuities in the pipe.

Ultrasonic inspection of pipelines

Stress in a material is measured using electromagnetically generated, transverse elastic waves. A correlation is known to exist between the difference in velocity of orthogonally polarized transverse waves in the type material being measured and stress in the material. An electromagnetic transducer is used to generate orthogonally polarized waves traveling through the part at different velocities as a result of anisotropic stress in the part. The difference in velocity between the polarized waves is measured and compared to the correlation to obtain the stress existing in the part.

Method of measuring stress in a material

Stress is detected by magnetostrictively generating vibrations which are detected at a location spaced from the region of generation. The efficiency of the generation is indicative of stress if the region is magnetically biased to less than maximum amplitude for the vibrations as produced. Preferably, the needed bias for generating vibrations at a constant level is used as stress indicator. Due to reciprocity of magnetostriction, the efficiency of generating magnetic oscillations by means of elastic vibrations in a biased region can be detected.

Growing community of inventors

Boulder, CO, United States of America

George A Alers