Showing papers on "Ultrasonic testing published in 1982"

Ultrasonic inspection of composite materials

Abstract: A method of ultrasonically inspecting the internal structure of a multi-ply composite material using ultrasonic transducers includes the steps of positioning an ultrasonic transmitter in acoustical contact with one surface of the material, directing a beam of acoustic energy into the material with the angle of incidence of the beam with respect to the surface being less than the second critical angle for the material but greater than normal to the surface, and receiving the reflected energy In one embodiment, the transmitting and receiving transducers are positioned with their axis perpendicular to the orientation of the reinforcing fibers within the ply being inspected In another embodiment, the transmitter and receiver are aligned at equal angles on either side of a line which is perpendicular to the orientation of the fibers The receiver may be located on the same or the opposite side of the material from the transmitter Internal cracks within each layer of the composite material can be detected along with information regarding their length and number Further, by precessing the transducers, the orientation of the fibers within each ply will be revealed and this information may be used to confirm proper construction of the composite Also, information regarding fiber overlap, wavyness and other characteristics of the composite with each ply can be ascertained

Ultrasonic measuring apparatus

Abstract: Ultrasonic measuring apparatus has a probe including ultrasonic transducer elements (2-1, 2-1', 2-2) capable of simultaneously transmitting or of simultaneously receiving ultrasonic beams of different frequencies (f1, f2). The apparatus provides for selective operation of transducer elements (e.g. 2-1 and 2-2 operated together; or 2-1, 2-1', 2-2 operated together) to change the shape of an effective acoustic field of at least one of the beams (e.g. the f2 beam). Thereby effective acoustic fields of the beams of different frequencies can be caused to coincide over selected distance-from-the-probe ranges.

Ultrasonic transducer coupler for flaw detection systems

Abstract: In the ultrasonic inspection of test pieces, particularly tubular materials, a device for coupling a transducer to the surface of the test material, by a liquid medium, incorporates desirable features of both "contact" and "immersion" transducers. Disclosed is a coupler the housing of which has a cavity having a water supply inlet and an air exhaust vent. Water flow into the cavity if so controlled as to initially purge air from the cavity to fill it with water, after which the water flow is at a carefully controlled rate effective to keep the cavity filled while supplying fresh water only to the extent necessary to make up for water leaking out through a narrow gap defined between the test piece and the face plate of the disclosed coupler. The water within the cavity provides a liquid couplant between the test piece and a transducer carried by a holder mounted in the cavity for precision adjustment. The transducer is in itself adjustable in respect to the holder in each position to which the holder is adjusted. In this way, precision focussing of an ultrasonic beam is attained. Precise control of the incidence and refraction angles of the propagated ultrasonic waves is thereby achieved accompanied by a desirable concentration of the ultrasonic energy in a specific target region of the test piece.

Ultrasonic inspection system

Abstract: Multi-channel automatic on-line ultrasonic inspection system for real time high-speed pulse echo testing is done across the width of a hot moving workpiece, such as steel plates and the like. In addition to a multiplexed transducer array search unit, the system includes an adjustable ultrasound fluid couplant, a main ultrasonic instrument modified with a digital multi-channel R.F. attenuation controller and a digital automatic flaw gate controller combined as on-line calibration means. The calibration means automatically corrects echo pulses for attenuation errors due to effects of variations in workpiece alloy or composition and temperature, and timing errors due to effects of variations in thickness and transducer gap, respectively. System further includes an ultrasonic data buffer/controller (UDBC) for digitizing, encoding and storing corrected or uncorrected flaw area data passed by the flaw gate during workpiece movement. The UDBC, together with a process control minicomputer, a display terminal and printer, provides computer-aided flaw area detection and reconstruction with printouts of an encoded flaw map and an A.S.T.M. flaw evaluation.

An Ultrasonic Device for Nondestructive Testing of Oilwell Cements at Elevated Temperatures and Pressures

Abstract: This paper describes a measuring technique and a hardware system that automatically monitors and records the complete history of compressive strength development and initial set of oil well cement slurries under high pressures and high temperatures (HP/HT). The design is based on the transmission characteristics of ultrasonic compressional waves through cement slurries. In principle, an analyzer measures the transit time (reciprocal of velocity) of an ultrasonic wave pulse through a slurry sample, converts it to apparent compressive strength, and records the results continuously. Compressive strengths, determined from ultrasonic transit time data, have shown deviations equal to or better than those obtained from mechanical tests. Since specimens are not removed and exposed to atmospheric pressure, the results should be more representative of actual downhole conditions. Also, the process promises to be well-suited to strength retrogression studies since there are no time gaps in the test results. Further experimental and analytical work is being carried out to evaluate the potential of this technique for measuring other slurry properties.

Ultrasonic testing of tubular goods

Abstract: Method and apparatus for ultrasonic flaw inspection of non-rotating tubular goods. The apparatus includes a test head with circumferential arrays of transducers oriented for inspection for each of transverse, longitudinal and wall thickness defects, and the test head includes individual pulser and pre-amplifier arrays as sequentially controlled from a remotely disposed operator console. The console includes sequential signal processing circuitry for developing and displaying defect indications for the test specimen as it is moved longitudinally through the test head.

Crack height measurement — an evaluation of the accuracy of ultrasonic timing methods

Abstract: Preliminary information was obtained on the accuracy and reliability of ultrasonic timing methods for crack height measurement. The investigation had two main aims: (1) to check the applicability of these methods to measurement of inclined defects; (2) measurement of the beam path-length to an accuracy of ± 0.01 mm for assessment of the accuracy of each method. The results showed that all of the ultrasonic timing method were highly accurate, provided that the angle of the probes used for the test was suitable. If accuracy alone was considered, the surface wave transmission method, though not suitable for inclined flaws, was the most accurate of all the timing methods examined.

An ultrasonic rail testing method and system

Abstract: A method and apparatus for ultrasonically inspecting railroad rails (20) utilizing a plurality of ultrasonic roller search units (12, 14, 16). Each search unit is a liquid filled elastomeric tire containing one or more ultrasonic transducers (35, 75, O, Z). The liquid couples the ultrasound between the rail and each transducer. The spaced wheels are in rolling contact with the rails being inspected. The system utilizes a plurality of differently oriented beams (32, 34, 36, 40, 50) of ultrasonic energy from the transducers which are pulsed at different times for probing various regions of the rails being inspected. The transducers receive through transmission or pulse echo ultrasonic energy from the workpiece and use such information to determine the location and nature of defects in the rail.

Process for ultrasonic testing of tubular goods

Abstract: A method for ultrasonic flaw inspection of non-rotating tubular goods using microprocessor central control. The system includes a test head with circumferential arrays of transducers oriented for inspection for each of transverse, longitudinal and wall thickness defects, and the test head includes individual pulser and pre-amplifier arrays as sequentially controlled from a remotely disposed operator console. The console includes signal processing circuitry and sequence controller for developing and displaying defect indications for the test specimen as it is moved longitudinally through the test head. The sequence controller contains resident program for addressably controlling the operational sequence of selected transducer pulsing, return signal reception, gate discrimination, and flaw signal averaging to provide qualified flaw output indication for each of the transverse, longitudinal and wall thickness testing modes.

Magnetic and ultrasonic objects testing apparatus

Abstract: Nondestructive object testing is carried out in a magnetic aspect as by leakage-flux detection and in an ultrasonic aspect by electromagnetic acoustic wave generation and detection, portions of magnetic flux being derived from a common source for the respective magnetic and ultrasonic testing.

Synthetic aperture ultrasonic testing apparatus with shear and longitudinal wave modes

Abstract: An ultrasonic synthetic aperture testing apparatus comprises transmitting/receiving sections having an ultrasonic wave probe for transmitting and receiving ultrasonic waves at multiple points on the surface of a steel material, an operation section for accumulating the received signals corresponding to the distance between the multiple points and a reproduction point in a desired region of the material under testing, and a display section for displaying an image formed as a result of this accumulation operation. The ultrasonic wave probe is provided with vibrators corresponding to the respective vibration modes so that two kinds of ultrasonic waves in different vibration modes may be transmitted and received. The accumulation section is provided with a mechanism which performs accumulation and arithmetic operation for the two kinds of waves in different modes.

A comparison of two calibration methods for ultrasonic hydrophones

Abstract: Although miniature ultrasonic hydrophones are frequently used to measure the acoustic pressure distributions from diagnostic ultrasound sources, relatively little attention has been devoted to the methods for absolute calibration of these hydrophones. In this study a polyvinylidene (PVDF) hydrophone was used to compare two calibration methods currently in use. One is based on a reciprocity technique and the second involves the planar scanning of a source transducer having a known radiated ultrasonic power. The reciprocity method revealed that the hydrophone response did not vary by more than ± 1.6dB from −262.8dB re 1V/μPa over the frequency range of 1–10 MHz. For the planar scanning technique seven ultrasound sources between 1–10 MHz were used, and all calibration points were within ±0.5 dB of the corresponding points found by the method of reciprocity.

Apparatus for ultrasonic testing of tubular goods

Abstract: Apparatus for ultrasonic flaw inspection of non-rotating tubular goods. The apparatus includes a test head with circumferential arrays of transducers oriented for inspection for each of transverse, longitudinal and wall thickness defects, and the test head includes individual pulser and pre-amplifier arrays as sequentially controlled from a remotely disposed operator console. The console includes sequential signal processing circuitry for developing and displaying defect indications for the test specimen as it is moved longitudinally through the test head. The signal processing circuitry includes separate processing channels for each of the transverse, longitudinal and wall thickness transducers, and each channel includes receiver, gate processing and average counter circuitry which develop data signals for output to selected chart and monitor scope indicators.

Non-destructive method and device for ultrasonic testing of the material of generator rotor teeth

Abstract: A process and a device for the nondestructive ultrasonic testing of the material of generator rotor teeth providing with an inserted slot wedge, using a probe arrangement including transmit probes, reference probes and defect detection probes which are disposed on a support plate in such a manner as to be movably attached to the teeth, wherein ultrasonic beams are transmitted and reflected by the rotor teeth flanks and the reflected beams are received in a reference probe utilizing a two-fold deflection of the sound at the tooth flanks which are inclined with respect to the tooth back. An ultrasonic beam, reflected by any existing defects of a given type and orientation, is selectively received outside the receiving range of the normally reflected acoustic beam by means of a defect detection probe, and the damaged locations is detected by comparison of the ultrasonic signals received by the reference and defect detection probes. Defects can be properly identified in rotor teeth having differing tooth flank angles by means of the two-fold beam deflection at the tooth flanks, and also with the use of additional reference probes.

Ultrasonic testing method and apparatus

Abstract: An ultrasound transducer 16 is coupled to a workpiece 10 by an elastomeric member 18 and measurements based on echoes returned from inhomogenities within the workpiece are initiated by detection of the echo from the interface between the workpiece and the coupling member. The device is particularly suited for measuring the extensions, and hence stressed in a bolt, while the compliant nature of the coupling member allows effective coupling even in the presence of surface irregularities such as the raised grade markings 14, on the bolt head 12.

Array Transducer Using New Modified PbTiO 3 Ceramics

Abstract: An array transducer using new modified PbTi03 ceramics has been developed for ultrasonic diagnostic equipments and NDE equipments This array transducer consists of many rectangular plate vibrators whose shape factor (W/T) is a large value, such as 20 (W: width, T: thickness) Adding Ca and Pb(CoW)fg03 to PbTiOj was proved to extend the coupling factor ratio by 2 times (Kt/Kp z 120) through the experiment Therefore, it has become possible to realize a large shape factor transducer (W/T >10) with no spurious vibration and low side lobe excitation This array transducer has good performance for longitudinal wave transducers, giving a good B-Scope image for the test piece in which weld-defects were artificially made

Ultrasonic method of determining nature of flaws by incremental scanning

Abstract: In ultrasonic flaw inspection for determining the size of a flaw by emitting an ultrasonic wave to a subject via a probe and receiving an ultrasonic echo from said flaw existing inside said subject, changes in the propagation distances of the ultrasonic echoes before and after movement of said probe through a micro-small distance are compared with each other and the ultrasonic echoes are determined to result from the same flaw if the change width falls within a predetermined value determined by the angle of incidence of the ultrasonic wave and the directional angle.

Method of testing fuel element tubes for defects

Abstract: The invention relates to a method for testing fuel element tubes by ultrasonic energy. For testing, each tube becomes disposed in the space between a transmit transducer and a receive transducer. The echo signals falling within a predetermined time interval are evaluated. Since the distance between the transducers may vary as the transducers move through the space between fuel element tubes, the transmitted signal reaching the receive transducer without passing through the tube may be confused with the revolving echo signal. Therefore, this invention discloses an arrangement for cyclically controlling the setting of the time gate before each such tube is in position between the transducers. To this end, the ultrasonic transit time of signals between the transmit transducer and the receive transducer is measured in the gap between the last tested tube and the next to be tested tube. A constant value is subtracted from the measured transit time value and this constant value is selected so that the transmitted signal received during the transit time measurement falls just outside the gated time interval.

Ultrasonic Tomography for Nondestructive Evaluation

Abstract: Ultrasonic inspection of manufactured parts has been widely used in industry for over 30 years (1, 2). Conventional methods, however, are largely limited to determining the presence or absence of defective regions in these parts without characterizing the detailed nature of the defect. As manufacturing methods have progressed and new, high-strength, high­ performance alloys have found widespread use, more detailed information about material parameters is required to assess the failure probability of parts in critical applications. One of the most promising new techniques that has been developed in recent years to deal with this need for quantitative materials information is ultrasonic tomography. This article reviews the current status of ultrasonic tomography in the context of the broader area of ultrasonic nondestructive evaluation (NDE). Tn particular, the role of ultrasonic tomography as one part of a large arsenal of NDE methods is examined in order to determine the area of application in which ultrasonic tomography can make the greatest contribution. Based on an assessment of available results (which are relatively few owing to the earJy stage of development of this field), some likely extensions of current techniques are suggested. Application of ultrasonic tomography to medical imaging, which is much more extensive because of its greater similarity to x-ray computerized tomography (CT), is not discussed here except as it directly impacts the NDE field.

Ultrasonic transducer probe for providing beams with adjustable angle

Abstract: The invention concerns an ultrasonic test probe for use in connection with testing workpieces wherein the angle of propagation of the ultrasonic search beam is adjustable. The probe comprises a linear array of ultrasonic transducer elements and a plastic wedge. An acoustic lens disposed between the array and the wedge causes the individual ultrasonic beams to come to a focus at an acoustic energy exit aperture of the probe. The angle adjustment of the ultrasonic beams is accomplished by energizing in-phase a respective group of transducer elements forming the array.

Ultrasonic pulse Doppler blood flow meter with provision to create ultrasonic test waves which, when reflected from a stationary object, result in echoes similar to those produced by a moving object

Abstract: An ultrasonic pulse Doppler blood flow meter which has: a rate pulse generator for outputting a rate pulse, a pulser receiving the rate pulse for outputting a drive pulse, a transducer excited by the drive pulse for transmitting an ultrasonic wave into an object to be detected and receiving the echoes thereof for converting the echoes into an electrical signal, a range gate circuit for outputting a sampling pulse after a predetermined time from the output of the rate pulse, a sample and hold circuit for sampling and holding the echo signals from the transducer in accordance with the sampling pulse, a converter for Fourier-converting the sampled echo signals, and a monitor for indicating in a intensity the converted echo signals advantageously further comprising: shifting circuit for shifting said predetermined time between the rate pulse and the range gate pulse at the individual periods of the rate pulse, and a switch circuit for selectively connecting the rate pulse generator and the shifting circuit to the drive pulse generator.

Measurement of the periodicity of internal surfaces by ultrasonic testing

Abstract: When an ultrasonic wave insonifies a corrugated surface it is diffracted in agreement with the optical laws. Diffraction peaks are observed and their positions are directly related to the periodicity of the grating. This property has been exploited to estimate the periodicity of an internal periodic surface. Experiments have been performed at 5 and 16 MHz for gratings engraved on different samples (plates and half cylinders) of various materials (copper, Perspex).