A density detection system uses a magnetic force feedback actuator positioner to maintain a precise selected pressure between transducer wheels and the surface of a sheet of material as the sheet of material moves through a position between transducer wheel and lift wheel. Consequently, the antiquated mechanical/pneumatic springs/airbags of prior art ultrasonic density detection systems are replaced with a highly responsive magnetic force feedback actuator positioner capable of providing a precise and relatively constant force that can react to the introduction of a sheet of material, and/or variations in the surface of a sheet of material, extremely rapidly without the bounce/recovery oscillations associated with prior art ultrasonic density detection systems. Consequently, precise density measurements of an entire sheet of material can be obtained with unprecedented accuracy.

The invention discloses a non-linear Lamb wave mixing method for measuring stress distribution in thin metal plates. The method is suitable for stress distribution detection and stress concentration area positioning in a plate structure and belongs to the field of nondestructive detection. The steps of the present invention is: first determines the excitation frequencies of two fundamental waves according to the measured object and the nonlinear Lamb wave mixing resonance conditions; the left and right ends of the test piece are oppositely excited two rows of A0 mode waves, and the excitation signal receive the sum-frequency S0 signal at a certain position to detect non-linear mixing stress of the plate structure; by changing the excitation time delay of the excitation signal, perform mixing scan on different positions of the test piece to extract the mixing wave amplitude; finally, according to the variation of amplitude of sum frequency difference signal with mixing position to realize the detection of stress distribution of metal plate and the positioning of the stress concentration area.

A probe arrangement for a testing system includes a base carrier that defines a longitudinal direction, which can be oriented parallel to a testing direction, and a transverse direction, which can be oriented perpendicularly to the testing direction. The base carrier carries a plurality of probe holders which are arranged next to one another in a row in the transverse direction. Each probe holder has a first probe region, which is equipped with at least one first probe, and a second probe region, which is equipped with at least one second probe. Each probe region defines an effective testing width such that, during relative movement of the test subject with respect to the probe arrangement along the testing direction through the probe region, a testing track having the effective testing width can be tested in a gap-free manner. The first probe region and the second probe region are arranged so as to be offset in relation to one another parallel to the longitudinal direction and parallel to the transverse direction such that a first testing track covered by the first probe region transitions on one side in a gap-free manner into a second testing track covered by the second probe region of the same probe holder, and transitions on the opposite side in a gap-free manner into a second testing track covered by a second probe region of a directly adjacent probe holder.

A method for reconstructing a three-dimensional surface of a part using an ultrasonic matrix sensor including scanning the three-dimensional surface using a matrix sensor at different measurement points located at the intersection of scanning rows and of increment rows at each measurement point, acquiring a temporal row image representing a reflected wave amplitude received by each element from a selected row of the matrix sensor and acquiring a temporal column image representing a reflected wave amplitude received by each element from a selected column of the matrix sensor, constructing a two-dimensional row image for each scanning row on the basis of the temporal row images constructing a two-dimensional column image for each increment row on the basis of the temporal column images, and constructing a three-dimensional image on the basis of the two dimensional row images and of the two-dimensional column images.

Network wavefield imaging methods are able to image significantly complex discontinuities or shapes in plate-like structures for superior ultrasonic structural health monitoring (SHM)/nondestructive evaluation (NDE). The imaging provides high-resolution location, shape and/or size images of a structure, and for discontinuities with more complicated profiles. Guided wave (GW) network wavefield imaging methods combine tomography and wavefield/wavenumber imaging algorithms. Metallic plate damage detection uses guided ultrasonic waves and non-contact laser vibrometry. Guided waves are generated by piezoelectric transducers (PZT). A non-contact scanning laser Doppler vibrometer (SLDV) measures the full velocity plate guided wave wavefields. Developed network wavefield imaging algorithms account for multiple-actuator excitations from different angles enclosing the discontinuity, with algorithms using intrinsic wave characteristics such as wavefield, wavenumber, or reconstructed wave energy. Determined locations, sizes and shapes of highlighted areas in wavefield, wavenumber and/or filter reconstructed energy-based images correlate with location, size and shape of damage in metallic plates.

Described is a method for estimating a material property of an object by means of a laser ultrasonic (LUS) measurement equipment comprising a generation laser, a detection laser and a detector. The method includes providing a laser pulse onto a surface of the object by the generation laser such that an ultrasonic pulse is generated in the object and such that an ultrasonic vibration is immediately generated on the surface, measuring at least a first subsequent ultrasonic echo from the object by use of the detection laser and the detector, which ultrasonic echo is an echo from the ultrasonic pulse generated in the object, measuring the ultrasonic vibration which is immediately generated on the surface, by use of the detection laser and the detector, and estimating the material property by use of an ultrasonic attenuation parameter based on the measured at least first subsequent ultrasonic echo, whereby the material property is estimated by using the measured ultrasonic vibration which is immediately generated on the surface as reference to the measured at least first subsequent ultrasonic echo.

The invention discloses a non-linear Lamb wave mixing method for measuring stress distribution in thin metal plates. The method is suitable for stress distribution detection and stress concentration area positioning in a plate structure and belongs to the field of nondestructive detection. The steps of the present invention is: first determines the excitation frequencies of two fundamental waves according to the measured object and the nonlinear Lamb wave mixing resonance conditions; the left and right ends of the test piece are oppositely excited two rows of A0 mode waves, and the excitation signal receive the sum-frequency S0 signal at a certain position to detect non-linear mixing stress of the plate structure; by changing the excitation time delay of the excitation signal, perform mixing scan on different positions of the test piece to extract the mixing wave amplitude; finally, according to the variation of amplitude of sum frequency difference signal with mixing position to realize the detection of stress distribution of metal plate and the positioning of the stress concentration area.

An autonomous metal-plate inspection apparatus, an inspection method, and a method for manufacturing a metal plate by using the inspection apparatus. The autonomous metal-plate inspection apparatus includes a carriage that travels on a surface of a metal plate, a navigational transmitter or a navigational receiver, an inspection device that includes flaw detection head including an inspection sensor, which scans an inspection region of the metal plate, and an inspection-result generation unit for generating an inspection result, and a control unit that performs, on the basis of a position of the carriage measured by the position measurement system and a target position, control the carriage to autonomously travel to the target position and control the flaw detection head to scan. The inspection-result generation unit generates the inspection result on the basis of inspection information obtained by the inspection sensor and position information of the flaw detection head.

A non-contact non-destructive testing method includes spatially and/or temporally controlling a laser excitation light based on a predetermined pattern. The laser excitation light is projected onto a surface of a test object to generate acoustic waves on the test object. The acoustic waves apply stress loading to the test object. The method also includes imaging the test object with and without stress loading using shearography imaging, and analyzing shearography imaging data to determine a presence of a defect in the test object.

A coupler and a chuck are described. The chuck is configured to secure an article while the wafer is undergoing an inspection process. The chuck has a plurality of vacuum areas. Some vacuum areas hold the wafer in place while other vacuum areas suction couplant from the edge surface of the wafer. The coupler is used to inspect a surface and subsurface of the wafer for defects and includes a sensing device, which may be a transducer. One or more couplant inlet couplings are disposed on a second portion of the coupler, the couplant inlet couplings provide a couplant to a portion of the wafer inspected by the sensing device. A plurality of vacuum inlet couplings is disposed on a third portion of the coupler. At least one of the vacuum inlet couplings provide suction through a recessed portion of a lower surface of the coupler to remove couplant that is outside the portion of the wafer that is being inspected by the sensing device.