Abstract: According to an embodiment, a nondestructive inspection method includes: detecting, by a plurality of sensors installed in a truck that supports a vehicle body, an elastic wave generated when a lifting member inserted between the vehicle body and the truck moves the vehicle body up and down; and estimating, by an evaluation device, a position of a defect in the truck, based on the elastic wave detected by the plurality of sensors.

Abstract: An ultrasonic inspection apparatus for an ultrasonic inspection system for inspecting a railway track, the ultrasonic inspection system for attaching to a bogie for pulling over the railway track, comprising a framework for attaching to the bogie, a sled for inspecting a rail, the sled carrying an array of ultrasonic transducers for detecting flaws in the rail, the system further comprising a water subsystem for ensuring fluid coupling between the sled and the rail, automatic lateral position rectification subsystem for keeping the sleds centered over the railway tracks as the train moves along the track, the ultrasonic transducers in data communication with a computing system in a wagon over the bogie for analyzing and mapping the flaws in the rail, wherein at least one pair of ultrasonic transducers is mounted in the same housing thereby shortening the length of the sled to be irrigated.

Abstract: There is provided detection instrumentation for the detection of transverse rail defects in rail head hitherto considered untestable on account of acoustic signal attenuation problems of horizontal lamination defects. The detection instrumentation comprises a pulse-echo acoustic transducer having a wear face for contacting a fillet of the rail and being aimed towards a head of the rail such that the transmitter transmits acoustic signals into the head and the receiver receives acoustic signals reflected at differing depths within the head. A signal receiver operably coupled to the receiver times the acoustic signals according to a timeseries railhead depth position scale. Analysis of the depth positions of the reflected acoustic signals according to relative positioning of the instrumentation along the rail may identify the transverse rail defects.

Abstract: An apparatus and method for rail inspection include a inspection carriage that moves atop a rail and carries a rail height sensor directed toward the rail. The rail height sensor generates a signal correlated with a vertical position (height) of the rail relative to the carriage as the carriage moves along the rail. A signal processor converts the rail height signal to a log of rail heights along the rail. Further processing of the log, e.g., in the signal processor, identifies crushed head defects in the rail.

Abstract: A system in accordance with one embodiment comprises a marking device attached to a holonomic-motion crawler vehicle capable of movement on non-horizontal surfaces. Modular attachment and motion control interfaces on the platform allow attachment of various types of marking and non-destructive inspection (NDI) sensor modules. The crawling vehicle marks the location of sub-surface features on an aircraft skin or overlaid patch (doubler) using a pen or sticker or tape applicator that is guided based on either a 3-D CAD model or NDI data collected as the vehicle crawls. A second embodiment utilizes an automated NDI scanner to collect 2-D image data of the substructure to enable manual or automated feature/edge selection for marking. Location tracking of the marking device can be implemented using a local positioning system or a motion capture system.

Abstract: An ultrasonic rail inspection system designed to detect defects in a rail which result from longitudinal cracks that propagate in the horizontal and transverse plane of the rail. Detection of this type of defect is possible by directing an ultrasonic beam into the rail at a predetermined angle from the perpendicular to the surface of the rail. The predetermined angle must be sufficient to detect these normally undetectable defects and can be in the range of 8° to 14° from the perpendicular.

Abstract: A method for acoustically examining a route includes sensing passively excited residual sounds of a vehicle system during travel over a route, examining the passively excited residual sounds to identify one or more changes of interest in the passively excited residual sounds, and identifying a section of the route as being damaged responsive to the one or more changes of interest in the passively excited residual sounds that are identified.

Abstract: An automatic sonic/ultrasonic data acquisition system for collecting data from concrete railroad ties. The system has a frame, a wheel carried by the frame and constructed and arranged to rotate relative to the frame such that the wheel can roll along the top of a rail, an axle suspended from the frame and adapted to be rotated relative to the frame via rotation of the wheel, one or more sensors coupled to the axle and constructed and arranged to contact the ties as the frame is moved along the rails, and an energy source for initiating in the ties compressional and/or shear/Rayleigh waves that are sensed by the sensors.

Abstract: A system and methods with which changes in microstructure properties such as grain size, grain elongation, texture, and porosity of materials can be determined and monitored over time to assess conditions such as stress and defects. An example system includes a number of ultrasonic transducers configured to transmit ultrasonic waves towards a target region on a specimen, a voltage source configured to excite the first and second ultrasonic transducers, and a processor configured to determine one or more properties of the specimen.

Abstract: A rolling search unit including an ultrasonic device and a heat exchanger mounted within a fluid-filled tire may be utilized to perform ultrasonic testing on an underlying railroad rail. The ultrasonic device may transmit or receive ultrasonic beams into or from the railroad rail, and the heat exchanger may be utilized to maintain the temperature of the fluid within the tire at a preferred level or within a preferred range. In such a manner, the results of testing obtained using the rolling search unit may be standardized regardless of the ambient temperature in the environment where the testing is being performed, and regardless of any heat gained or lost by the rolling search unit during operation.

Abstract: An apparatus for detecting defects in a railway rail mounted on a test vehicle. The apparatus includes a transducer assembly with one or more arrays of ultrasonic transducers directed toward the running surface of the rail. Beams transmitted by the one or more arrays of ultrasonic transducers may be dynamically adjusted to compensate for the varying profile of the rail head and running surface. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data, which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

Abstract: The invention refers to a device for attachment to a rotating part (1) of a railway vehicle incorporating an arrangement, which is adapted, during movement of the railway vehicle, to detect and evaluate parameters related to the railway vehicle service and/or to an incipient fault state of wheel bearings (2) in the railway vehicle, and which device (12) is arranged to emit signals representative for the detected and evaluated parameters.

Abstract: A rolling search unit including an ultrasonic device and a heat exchanger mounted within a fluid-filled tire may be utilized to perform ultrasonic testing on an underlying railroad rail. The ultrasonic device may transmit or receive ultrasonic beams into or from the railroad rail, and the heat exchanger may be utilized to maintain the temperature of the fluid within the tire at a preferred level or within a preferred range. In such a manner, the results of testing obtained using the rolling search unit may be standardized regardless of the ambient temperature in the environment where the testing is being performed, and regardless of any heat gained or lost by the rolling search unit during operation.

Abstract: An apparatus for detecting defects in a railway rail mounted on a test vehicle. The apparatus includes a transducer assembly with one or more arrays of ultrasonic transducers directed toward the running surface of the rail. Beams transmitted by the one or more arrays of ultrasonic transducers may be dynamically adjusted to compensate for the varying profile of the rail head and running surface. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data, which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

Abstract: A rolling search unit including an ultrasonic device and a heat exchanger mounted within a fluid-filled tire may be utilized to perform ultrasonic testing on an underlying railroad rail. The ultrasonic device may transmit or receive ultrasonic beams into or from the railroad rail, and the heat exchanger may be utilized to maintain the temperature of the fluid within the tire at a preferred level or within a preferred range. In such a manner, the results of testing obtained using the rolling search unit may be standardized regardless of the ambient temperature in the environment where the testing is being performed, and regardless of any heat gained or lost by the rolling search unit during operation.

Abstract: A method for detecting defects in a railway rail including a search unit and preferably a roller search unit (“RSU”) mounted on a test vehicle and in rolling contact with the running surface of the rails to inspect each rail. The RSU includes a tire filled with a liquid and a transducer assembly mounted within the tire. The transducer assembly includes one or more arrays of ultrasonic transducers directed toward the running surface of the rail. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to dynamically steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

Abstract: A method for detecting defects in a railway rail including a search unit and preferably a roller search unit (“RSU”) mounted on a test vehicle and in rolling contact with the running surface of the rails to inspect each rail. The RSU includes a tire filled with a liquid and a transducer assembly mounted within the tire. The transducer assembly includes one or more arrays of ultrasonic transducers directed toward the running surface of the rail. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to dynamically steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

Abstract: An ultrasonic rail inspection system designed to detect defects in a rail which result from longitudinal cracks that propagate in the horizontal and transverse plane of the rail. Detection of this type of defect is possible by directing an ultrasonic beam into the rail at a predetermined angle from the perpendicular to the surface of the rail. The predetermined angle must be sufficient to detect these normally undetectable defects and can be in the range of 8° to 14° from the perpendicular.

Abstract: An apparatus for detecting defects in a railway rail includes a search unit and preferably a roller search unit (“RSU”) mounted on a test vehicle and in rolling contact with the running surface of the rails to inspect each rail. The RSU includes a tire filled with a liquid and a transducer assembly mounted within the tire. The transducer assembly includes one or more arrays of ultrasonic transducers directed toward the running surface of the rail. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to dynamically steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

Abstract: An apparatus for detecting defects in a railway rail includes a search unit and preferably a roller search unit (“RSU”) mounted on a test vehicle and in rolling contact with the running surface of the rails to inspect each rail. The RSU includes a tire filled with a liquid and a transducer assembly mounted within the tire. The transducer assembly includes one or more arrays of ultrasonic transducers directed toward the running surface of the rail. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to dynamically steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

Abstract: An apparatus for detecting defects in a railway rail includes a search unit and preferably a roller search unit (“RSU”) mounted on a test vehicle and in rolling contact with the running surface of the rails to inspect each rail. The RSU includes a tire filled with a liquid and a transducer assembly mounted within the tire. The transducer assembly includes one or more arrays of ultrasonic transducers directed toward the running surface of the rail. A laser profiler mounted on the test vehicle in combination with a linear encoder provide profile data which is communicated to a system controller to dynamically adjust the focal laws for the one or more arrays of transducers to dynamically steer the transmitted beams to produce the ideal inspection beam sets while the test vehicle is in motion.

Abstract: An apparatus and method for inspecting a rail joint bar transported along a railway rail by an inspection vehicle is provided. The apparatus and method includes a pair of ultrasonic transducers housed in liquid-filled wheels. The wheels are positionable for a stored position to a measurement position in rolling contact with the vehicle surfaces of the rail joint bars on each side of the rail. The ultrasonic transducer transmits a signal into the rail joint bar and the reflected signal is detected by the transducer and analyzed to identify flaws in the rail joint bar.

Abstract: An ultrasonic probe includes a probe body having a contact surface and a cavity that is open at the contact surface, an ultrasonic transducer carried by the body, and a spacer within the cavity. The spacer has a first surface acoustically coupled to the transducer, and a second (coupling) surface within the cavity. The spacer propagates an acoustic signal between the transducer and the coupling surface. The coupling surface is spaced apart from the contact surface to form a recess within the body. The body further has at least one port for circulating a coupling fluid into the recess. Depth of the recess is selected to balance gravitational force on the coupling fluid versus surface tension of the coupling fluid so a bead of the fluid forms over an edge of a structure under inspection as the probe is moved over the edge.

Abstract: A rail defect detection system includes a controller in signal communication with at least one transducer. The at least one transducer is configured to receive a predetermined number of guided elastic wave modes at specific frequencies and with specific wave structures from a rail and generate a signal in response. The controller includes a processor configured to identify a defect disposed along the rail in response to the signal received from the at least one transducer.

Abstract: A rail scanning system and certified method of use thereof are described. The rail scanning system comprises a control unit, a probe carriage, and an encoder. The probe carriage comprises two or more phased array probes. The control unit is communicatively coupled with the encoder and phased array probes of the probe carriage.

Abstract: A method for imaging internal flaws of a rail is disclosed. The method may include transmitting multiple ultrasound pulses into the rail along transverse and longitudinal axes of the rail, acquiring reflected ultrasound data from the rail, processing the reflected ultrasound data by applying an ultrasound migration technique to the reflected ultrasound data, and mapping the internal flaws of the rail based on the reflected ultrasound data processed by the ultrasound migration technique.

Abstract: A rail scanning system and certified method of use thereof are described. The rail scanning system comprises a control unit, a probe carriage, and an encoder. The probe carriage comprises two or more phased array probes. The control unit is communicatively coupled with the encoder and phased array probes of the probe carriage.

Abstract: A system (1) for the detection of defects in rails (12), the system comprising a source of ultrasonic waves for emitting ultrasonic waves onto a rail, a detector for detecting ultrasonic waves reflected or otherwise scattered by the rail or defects therein and a mist generator (3) arranged, in use, to expose one or both of the rail and source of ultrasonic wave to a mist of liquid, thus enabling the formation of an ultrasound-transmissive interface between the rail and the source of ultrasonic waves.

Abstract: A method for identifying a location of a wheel of a rail vehicle includes producing a first signal representative of a potential difference between leads electrically coupled with a wheel gate transducer and modifying the first signal that is received over a first channel to produce a second signal over a second channel, where the second signal differs from the first signal. The method further includes monitoring the first and second signals over the first and second channels to identify the location of the wheel relative to the wheel gate transducer.

Abstract: A method for detecting flaws in a railhead, which railhead (1) is provided with a top side (T), a bottom side (B) and longitudinal sides (S) extending between that top side (T) and bottom side (B), wherein at least one ultrasonic first signal (10) is transmitted into the railhead (1) via said head top side (T) and traverses such a transmission path (9) that: —the signal (10) is only once reflected by the railhead bottom side (B), and not by a railhead longitudinal side (S); —the signal (10) reaches at least one substantially central railhead part (C); and —the signal (10) can exit the railhead (1) via the head top side (T); wherein first ultrasonic signals exiting the head top side (T) are detected, wherein the transmission path (9) of the at least first signal (10) extends in a virtual transmission plane, which transmission plane extends substantially transverse to a longitudinal direction (L) of the rail. In addition, the invention provides an apparatus for detecting flaws in a railhead.

Abstract: An apparatus and method for inspecting a rail joint bar transported along a railway rail by an inspection vehicle is provided. The apparatus and method includes a pair of ultrasonic transducers housed in liquid-filled wheels. The wheels are positionable for a stored position to a measurement position in rolling contact with the vehicle surfaces of the rail joint bars on each side of the rail. The ultrasonic transducer transmits a signal into the rail joint bar and the reflected signal is detected by the transducer and analyzed to identify flaws in the rail joint bar.

Abstract: The invention refers to a device for attachment to a rotating part (1) of a railway vehicle incorporating an arrangement, which is adapted, during movement of the railway vehicle, to detect and evaluate parameters related to the railway vehicle service and/or to an incipient fault state of wheel bearings (2) in the railway vehicle, and which device (12) is arranged to emit signals representative for the detected and evaluated parameters.

Abstract: A system and methods with which changes in microstructure properties such as grain size, grain elongation, texture, and porosity of materials can be determined and monitored over time to assess conditions such as stress and defects. The present invention includes a database of data, wherein a first set of data is used for comparison with a second set of data to determine the conditions of the material microstructure.

Abstract: An apparatus for ultrasonic inspection of an object. A tire is mounted for rolling along the surface of the object. It contains a liquid and a transducer assembly. The transducer assembly is positioned in the tire adjacent a portion of the surface of the tire in contact with the object. The liquid and the surface of the tire in contact with the object provide an acoustic bridge between the transducer assembly and the object. An electric signal processing system is connected to the transducer assembly. It generates electric signals which are converted to acoustic signals in the transducer assembly to place acoustic signals in the object. Acoustic signals returned from the object are converted to electric signals by the transducer assembly, and are processed in the electric signal processing system to indicate flaws in the object.

Abstract: An ultrasonic railroad rail inspection system, apparatus and method for in situ rail inspection including a wheel assembly containing a fluid-filled tire and an ultrasonic transducer mounted within the wheel assembly. The transducer is supported in the tire such that the ultrasonic beam generated by the transducer has a beam axis that intersects a head of a railroad rail at a position offset from the longitudinal median plane of the rail to the side of the head penetrated by the ultrasonic beam. The ultrasonic beam is reflected by flaws in the rail in the form of echoes. The echoes return to the transducer identifying the location of flaws.

Abstract: A method for ultrasonic testing of an object, wherein at least one test moment an ultrasonic test signal (S1, S2) is transmitted into the object (2), while after a particular verification period (?t1, ?t2) measured from said test moment, an ultrasonic verification signal (S1?, S2?) is transmitted into the object (2), a possible echo of said test signal (S1, S2) being received from said object (2) at a particular first measuring moment, the possible echo being accepted as being the echo (E1, E2) of said test signal (S1, S2) only when the echo (E1?, E2?) of the verification signal is received at a particular second measuring moment. In addition, the invention provides an apparatus, evidently intended and designed for carrying out such a method and a use of such an apparatus.

Abstract: A system is provided for measuring a distance within a railroad system. The railroad system includes a rail vehicle having a plurality of pairs of wheels, where the plurality of pairs of wheels are in respective contact with a pair of rails. The system further includes a transducer positioned on an outer surface location of the rail vehicle. The transducer is configured to emit a signal to an object located the distance away from the transducer. The transducer is configured to receive the signal having reflected from the object along the distance to the transducer. The system further includes a controller coupled to the transducer to receive transmission and reception data of the signal to determine the distance. A method is also provided for measuring a distance within a railroad system, as well as a kit for converting a rail vehicle from a first configuration to a second configuration.

Abstract: A method of inspecting a radius area of composite parts with an ultrasonic inspection system, the system includes at least one ultrasonic probe, an upper sliding surface, a lower sliding surface, an adjustable guide rail, and an adjustable encoder wheel rotatably coupled to a rotary encoder, is provided. The method includes generating a high frequency sound wave using the probe including a radius of curvature extending from a center point, the sound wave travels partially through the part, adjusting the guide rail to align the center point of the probe with a center axis of a part corner portion, sliding the part through the inspection system to inspect the corner portion using the sound wave by rotating the wheel and rotary encoder such that the arcuate distance of the part is recorded, adjusting the wheel to avoid any apertures defined within the part, and processing the sound wave information.

Abstract: A system (1) for the detection of defects in rails (12), the system comprising a source of ultrasonic waves for emitting ultrasonic waves onto a rail, a detector for detecting ultrasonic waves reflected or otherwise scattered by the rail or defects therein and a mist generator (3) arranged, in use, to expose one or both of the rail and source of ultrasonic wave to a mist of liquid thus enabling the formation of an ultrasound-transmissive interface between the rail and the source of ultrasonic waves.

Abstract: An ultrasonic railroad rail inspection system, apparatus and method for in situ rail inspection including a wheel assembly containing a fluid-filled tire and an ultrasonic transducer mounted within the wheel assembly. The transducer is supported in the tire such that the ultrasonic beam generated by the transducer has a beam axis that intersects a head of a railroad rail at a position offset from the longitudinal median plane of the rail to the side of the head penetrated by the ultrasonic beam. The ultrasonic beam is reflected by flaws in the rail in the form of echoes. The echoes return to the transducer identifying the location of flaws.

Abstract: An ultrasonic rail inspection system designed to detect defects in a rail which result from longitudinal cracks that propagate in the horizontal and transverse plane of the rail. Detection of this type of defect is possible by directing an ultrasonic beam into the rail at a predetermined angle from the perpendicular to the surface of the rail. The predetermined angle must be sufficient to detect these normally undetectable defects and can be in the range of 8° to 14° from the perpendicular.

Abstract: An ultrasonic rail inspection system designed to detect defects in a rail which result from longitudinal cracks that propagate in the horizontal and transverse plane of the rail. Detection of this type of defect is possible by directing an ultrasonic beam into the rail at a predetermined angle from the perpendicular to the surface of the rail. The predetermined angle must be sufficient to detect these normally undetectable defects and can be in the range of 8° to 14° from the perpendicular.

Abstract: A method of detecting defects in a railway track rail, the rail (101) having a longitudinal centre plane and a surface, the surface including a running surface (102), the method comprising directing an excitation laser beam (106) to an excitation position (103) on the surface of the rail (101) to induce an ultrasonic wave in the rail (101); and directing a detection laser beam (108) to a detection position (104) on the surface of the rail (101) to detect at least one predetermined property of the induced ultrasonic wave; wherein the excitation position (103) and the detection position (104) are located on the running surface (102) and displaced from the longitudinal centre plane of the rail (101).

Abstract: An apparatus rides along a rail of a railroad track. A transmitter transmits ultrasonic guided waves bidirectionally along the rail while the apparatus and transmitter are moving along the railroad track. A sensor detects flaws in response to the transmitted ultrasonic guided waves while the apparatus, transmitter and sensor are moving along the railroad track. An electronic coupler operatively couples the sensor to monitoring equipment.

Abstract: An inspection system for inspecting a three-dimensional volume. The inspection system comprises at least one sensor coupled to a rolling object, the sensor being disposed on a non-contact outer region of the rolling object and at a pre-determined distance from a center of the rolling object. The sensor is configured to generate a signal representative of a condition of a region on the three dimensional volume.

Abstract: The present invention relates to a failure detecting system that enables the detection of a break in a rail and the like by a simple network configuration. Detecting units (20 and 50), relay units (30A, 30B, 60A through 60C) and terminal units (40 and 70) are arranged along rails (11, 11A and 11B). Using the rails (11, 11A and 11B) as transmission media, ultrasonic waves transmitted from the detecting units (20 and 50) are transmitted to the terminal units (40 and 70) by the relay units (30A, 30B, 60A through 60C), and when the terminal units (40 and 70) receive the ultrasonic waves, the ultrasonic waves are returned from the terminal units (40 and 70), relayed by the relay units (30A, 30B, 60A through 60C), and transmitted to the detecting units (20 and 50). Thus, it is judged whether there is a break in the rails (11, 11A and 11B), based on the ultrasonic wave reception state in the detecting units (20 and 50).

Abstract: A vehicle equipped with monitoring equipment is adapted to ride a railroad track rail. An apparatus mount is coupled to the vehicle undercarriage. A downwardly displaced arm is coupled to the apparatus mount. A sensor mounting bracket couples a pair of railroad wheels and a pair of wheel bracket axles couples the wheels to the mounting bracket. A wheel axle couples one wheel to the arm. A sensor is positioned at a fixed adjustable distance above the top of the rail. The sensor is coupled to monitoring equipment with an electronic coupling means.

Abstract: A remote, non-contact system for detecting a defect in a railroad wheel as the wheel is stationary or moving along a railroad track includes; (1) a pulsed, laser light source for generating an ultrasonic wave in the wheel, the ultrasonic wave having a direct portion and reflected and transmitted portions if the direct portion encounters a defect in the wheel, (2) an optical component in the path of the light from the light source for forming the light into a specified illumination pattern so that the generated ultrasonic wave has a specified wavefront, (3) an air-coupled transducer or a group of transducers for sensing the acoustic signal emanating from the wheel that results from the ultrasonic wave traveling through the wheel, and (4) a signal processor, responsive to the sensed acoustic signal, capable of distinguishing whether the sensed signal has a component that indicates the existence of a reflected portion in the ultrasonic wave, wherein the presence of such a component in the acoustic signal indicat

Abstract: Apparatus for inspecting a non axi-symmetric elongate body includes at least one exciter array having a plurality of wave exciters that can be coupled to an exterior surface of the elongate body. A driver unit generates driving signals to excite the wave exciters. Each driving signal for a respective wave exciter in the array is weighted with respect to driving signals to the other wave exciters in the array such that a specific guided acoustic wave mode is excited. A receiving unit includes a plurality of wave receivers for receiving reflected guided acoustic waves. An analysis unit analyzes received waves to assess a condition of the non axi-symmetric elongate body.

Abstract: There is described apparatus for inspecting a non axi-symmetric elongate body comprising: at least one exciter array having a plurality of wave exciters operable to couple to an exterior surface of said elongate body; a driver unit operable to generate driving signals to excite said plurality of wave exciters wherein each driving signal to a respective wave exciter of said array is weighted with respect to driving signals to other wave exciters in said array such that a guided acoustic wave mode is excited; a receiving unit having a plurality of wave exciters in said array such that a guided acoustic wave mode is excited; a receiving unit having a plurality of wave receivers capable of receiving reflected guided acoustic waves; an analysis unit operable to analyse received waves to assess a condition of said non axi-symmetric elongate body.