Ultrasonic Inspection Methods Research Articles

Comparisons of non-destructive examination standards in the framework of fracture mechanics approach

One of the aims of the various Engineering Standards related to Non-destructive Examination (NDE) is to identify and limit some characteristics of defects in a structure. Since the degree of damage of a structure can be associated with these defect characteristics. One way that the damage level can be evaluated is by means of Fracture Mechanics. The objective of the present paper is to compare and identify the differences in the flaw acceptance criteria of national NDE Standards so as to suggest some guidelines for a future common European Standard. This paper examines the Standards adopted in France (RCC-MR), Germany (DIN), Italy (ASME) and the UK (BSI). It concentrates on both ultrasonic and radiographic inspection methods. The flaw acceptance criteria in these standards relating to non-destructive tests performed on a component during manufacturing are compared and evaluated by the Fracture Mechanics CEGB R6 procedure. General guidelines and results supporting the significance of the Fracture Mechanics approach are given.

SWEPT FREQUENCY ULTRASONIC INSPECTION METHOD FOR LINER-PROPELLANT SEPARATIONS OF SOLID ROCKET MOTORS

Abstract This paper describes the swept frequency type of ultrasonic inspection method that is usable for inspecting liner-propellant separations of solid rocket motors and successful application of the method to the H-I upper-stage motors. Unfortunately, over the past quarter of a century, the liner-propellant separations have never been inspected practically with usual ultrasonic inspection methods. The special method has been developed at the National Aerospace Laboratory (NAL) since 1968, and the inspection technique is based on the one-dimensional quarter-wavelength resonance principle for the liner thickness under one free and the other fixed end-face boundary condition, which is considered the linear-propellant separation boundary condition of the linear. Since the motor cases have curved (spherical or cylindrical) surfaces, some curved contact surface probes were developed. This method was successfully applied to the apogee and third stage motor of the H-I rocket at the manufacturer and then at th...

Swept frequency type of ultrasonic inspection method for liner-propellant separations of the H-I upper-stage motors

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

UK developments in the ultrasonic examination of pressure vessels

This paper reviews developments in the UK of ultrasonic inspection methods for both in-service inspection of existing, older plant and also for the proposed PWR at Sizewell. In the case of existing plant there are problems which stem from the fact that ultrasonics was not in widespread use at the time the reactors were designed and constructed. Consequently weld geometries, surface finishes and access pose difficulties which must be overcome by developments in the way ultrasonics is applied. For the PWR, the reactor has been designed from the outset with inspection in mind. The safety case requires a demonstration that certain parts, including the reactor pressure vessel, cannot fail and this, in turn, involves a demonstration of high inspection reliability. Such a demonstration has necessitated a range of developments to understand and quantify the way sound reflects from a variety of metallurgical defects. The ultrasonic inspections carried out for Sizewell B involve extensive use of automated techniques during fabrication. These have also been the subject of intensive development in the UK.

Elastic waveforms using laser generation and electromagnetic acoustic transducer detection

A Q-switched, frequency-doubled ruby laser has been used to generate wide bandwidth ultrasonic transients in aluminum and steel plates. Both longitudinal and shear waves were generated, resultant waveforms being dependent upon the irradiation conditions. Various designs of electromagnetic acoustic transducers were then used to detect these waveforms at the opposite side of the plate. The result is a method of ultrasonic inspection with potential in noncontact applications.

Real-time ultrasonic weld inspection method

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電子走査形超音波探傷技術および装置

電子走査形超音波探傷技術および装置

Calculation of the velocity of creeping waves and their application to non-destructive testing

A method of ultrasonic inspection called ‘time-of-flight’ is intended to provide accurate sizing of crack-like defects in structures such as pressure vessels and piping and the principles can also be applied to the sizing of volumetric defects. Accurate measurement can only be made if the velocity of the ultrasonic wave is known along the entire path. For structures that have curved surfaces (as do pressure vessels and piping) and for the sizing of volumetric defects, this aspect is important for the so-called creeping waves that propagate around the curved surfaces, comparable to the ‘lateral’ or ‘near-surface’ waves on a flat plate. It is shown that the velocity of creeping waves is a sensitive function of the curvature of the surface. The velocity can be predicted accurately from the bulk wave velocity and the radius of curvature of the defect. Detailed calculations are made for steel and are discussed in terms of 4 MHz ultrasonic waves. The results have consequences relating to the accurate sizing by time-of-flight methods of volumetric defects or for accurate depth determination of crack-like defects in pressure vessels and piping.

Evaluation of pipeline girth welds using low-frequency horizontally polarized waves

The practical implementation of alternative acceptance criteria for pipeline girth welds requires the use of inspection tools capable of determining the principal dimensions and positions of planar flaws. A new ultrasonic inspection method is described that permits complete volumetric inspection of the girth welds. The new system uses noncontacting electromagnetic-acoustic transducers (EMATs) that operate at low ultrasonic frequencies (454 kHz). Theoretical models of the measurements are developed and verified experimentally. In addition, practical performance limits of the new system are established in terms of minimum flaw sizes that can be detected. The results are related to accept-reject curves based on a model of the failure processes. An inspection protocol for field applications is also described.

Dynamic photoelasticity as an aid in developing new ultrasonic-test methods

A prerequisite for the development of quantitative ultrasonic-inspection techniques for surface flaws is a thorough understanding of the ways in which elastic waves interact with defects. Analytical and numerical approaches are presently inadequate. Experimental methods are needed for a better understanding of wave interactions with real geometries. This paper describes how dynamic photoelasticity was used to study the interaction between Rayleigh waves and slots. To fully interpret the interactions between an incident Rayleigh wave and a surface slot, the problem was subdivided as follows: first, the reflections and mode conversions of a Rayleigh wave at a corner were studied. This simulated the Rayleigh-wave interaction with a slot opening. Then, the interaction when a Rayleigh wave ran off the tip of a slot was observed, and, finally, the total interaction with slots perpendicular to the surface was studied. The results for these three cases are presented. It is suggested that the most important property of a Rayleigh wave that can be used to size surface and near-surface defects is the subsurface particle motions. These motions persist up to a depth of the order of a wavelength. The shape (that is, the frequency spectrum of the transmitted wave) should, therefore, be affected by the depth of the slot. Spectroscopic analysis is applied to the photoelastic data to develop a simple method for sizing slots. Results from ultrasonic tests on slots in steel confirm the validity of the suggested method. By applying contemporary concepts of signal processing to photoelastic data, a powerful new area of experimental investigation is introduced. It promises to overcome the current inability of scatter theories to predict the interactions between real-life defects and acoustic waves as used in ultrasonic testing. Applications of this approach will improve the quantitative ability of ultrasonic-inspection methods.

A standardless method of ultrasonic inspection of weld joints

A standardless method of ultrasonic inspection of weld joints

Quantitative use of Rayleigh waves to locate and size subsurface holes

An ultrasonic inspection method is used to obtain the circumference of a subsurface hole and the depth of the hole below the surface. A pitch-catch Rayleigh wave transducer set-up was used to launch a Rayleigh surface wave at the flaw and to capture and record the scattered waves. The frequency spectrum of the scattered waves can be used to obtain the depth of the hole. The ligament of material between the hole and the surface is sent into resonance, and this feature can be extracted from the scattered waves' frequency spectrum. The frequency is a function of the ligament length; thus the hole depth can be obtained. The circumference of the hole is found from a time of flight measurement. A Rayleigh wave is formed that travels around the hole's surface. The length of time required for the wave to travel around the hole is a measure of the circumference.

Apparatus and method for ultrasonic inspection of highly attenuative materials

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A standard-free method of ultrasonic inspection of forgings and stampings

A standard-free method of ultrasonic inspection of forgings and stampings

Ultrasonic inspection and fail-safe indication method and apparatus

Ultrasonic inspection and fail-safe indication method and apparatus

Ultrasonic inspection and fail-safe indication method and apparatus

Measurements of the two characteristic lengths of 6 glass wool samples (with flow resistivities between 11,900 and 69,900 Pa s m−2) and 6 polyester fibre samples (with flow resistivities between 4100 and 51,000 Pa s m−2) have been made. These data have been used to determine the cross-sectional shape factors which are related to the characteristic lengths introduced by Allard. By using the formulas due to Bies and Allard, it has been found that the two characteristic lengths of the glass wool samples can be independently predicted from the glass fibre diameter. In respect to polyester fibre samples, a new relation between the flow resistivity, the fibre diameter and the bulk density has been proposed and examined. The accuracy of the predictions of the non-acoustical parameters has been confirmed by the measurements and predictions of the absorption coefficient using the Delany and Bazley and Allard models.

Evaluation of the sensitivity of the contact and immersion method of ultrasonic inspection: Yablonik, L.M., Defectoscopy (English Translation) No 1 (January–February 1967) pp 10–13 (1309)

A resonance acoustic microbalance with a naked-embedded quartz (RAMNE-Q) is realized by a microfabrication method, aiming at broader applications of quartz-crystal microbalance (QCM) biosensors. The RAMNE-Q biosensor consists of three layers; a silicon layer with an engraved microchannel and sandwiching glass layers. The naked AT-cut quartz resonator of 9.3 or 28.5 μm thick is located in the microchannel and supported by the silicon micropillars and semicircular walls without fixing, and it is encapsulated by the rigid body. Cupper antennas are used for generating and receiving electromagnetic fields to excite and detect the shear vibration of the quartz oscillator during the solution flow, thereby achieving the noncontact measurement of the resonance frequency. Because of the isolated resonator, the Q factor is high enough (about 1500 at 170–180 MHz) even in the flowing solution. We succeeded in detecting 1 ng/ml human immunoglobulin G in phosphate-buffered-saline solution via Staphylococcus aureus protein A immobilized nonspecifically on the quartz surfaces, demonstrating the high sensitivity and high signal-to-noise ratio of the RAMNE-Q biosensor. It does not require electrodes and is a replacement-free biosensor, and its reusability is confirmed.

Ultrasonic Image Systems for Nondestructive Testing

Ultrasonic imaging techniques are finding increased application in the medical and industrial fields because the image presentation often offers the advantage of improved interpretation capability for the ultrasonic test. In the nondestructive testing field, ultrasonic imaging inspection methods have recently been expanded to include television techniques; the operation and application of these techniques are emphasized in this report. In addition to interpretation advantages, television methods can also present improved resolution capabilities and faster inspection speeds, as compared to other ultrasonic inspection methods. Continuous-wave ultrasonic television systems have shown promise as inspection methods for relatively thin, flat material in which inspection is desired to determine such things as bonding, particle size variations, or homogeneity. Flat, reactor fuel plates and thin metal spot welds are examples of materials for which this type of inspection has been shown to be useful. Pulsed inspection systems have also been demonstrated, with relatively slow image presentation rates. These systems, when further developed, offer promise for greater range of application. [This work was performed under the auspices of the U. S. Atomic Energy Commission.]

The ultra-sound image camera

The ultra-sound image camera enables a visible image to be reproduced of the ultra-sound intensity distribution on the camera face. Coupled with acoustic lenses, and immersed in a suitable medium, the internal structure of substances or objects transparent to ultrasonic waves can be studied with the instrument. In its uses it is complementary to X-ray and to ultrasonic pulse-echo inspection methods. It has applications to the non-destructive testing of materials and engineering components, and also to medical diagnosis.An ultra-sound camera tube and complete viewing equipment have been built. The sensitivity for unity signal/noise ratio is 10−7 W/cm2 at the camera face, and the resolution is 0.5 mm at 4 Mc/s. It is one of several possible types of ultra-sound camera. The design is discussed, and directions into which further research and development might be taken are also considered.

The ultra-sound image camera

The ultra-sound image camera enables a visible image to be reproduced of the ultra-sound intensity distribution on the camera face. Coupled with acoustic lenses, and immersed in a suitable medium, the internal structure of substances or objects transparent to ultrasonic waves can be studied with the instrument. In its uses it is complementary to X-ray and to ultrasonic pulse-echo inspection methods. It has applications to the non-destructive testing of materials and engineering components, and also to medical diagnosis.An ultra-sound camera tube and complete viewing equipment have been built. The sensitivity for unity signal/noise ratio is 10−7 W/cm2 at the camera face, and the resolution is 0.5 mm at 4 Mc/s. It is one of several possible types of ultra-sound camera. The design is discussed, and directions into which further research and development might be taken are also considered.