Time-of-flight diffraction ultrasonics

About: Time-of-flight diffraction ultrasonics is a research topic. Over the lifetime, 544 publications have been published within this topic receiving 3189 citations.

Non Destructive Evaluation by Time of Flight Diffraction Method Mechanical Applications

Abstract: The TOFD (time of flight diffraction method) which consists in an ultrasonic method for detection and dimensioning the discontinuities in the mechanical components, is more and more present in the industry. In some cases, the question of opportunity of using TOFD instead of X ray testing is discussed. This paper gives information about the interest and the limitations of the method, and its position in relation with X ray testing. Finally, applications of this method for mechanical engineering are described. Method still often ignored, the TOFD is a new process of ultrasonic control. The recent studies concerning this technique showed its effectiveness and its speed, and its competitiveness compared to radiography, without the disadvantages of the ionizing radiations. It is applied today in fields of control of the welded joints, but not only. In NDT community, the method is not yet known of all, and yet, in a few seconds, it allows the inspection of one meter welding on 50 mm thickness! A rather significant data when one knows that between the installation and measurements, other NDE methods require until several hours. Moreover, measurements are given in millimetres, detection does not depend on the orientation of the defect, and one can use it at high temperatures (up to 250°C). This method: the T.O.F.D. an acronym for Time of flight diffraction. Control TOFD has been increasingly popular, in fact, for these last years, more particularly in the laboratories and companies having a high level of expertise and which seek an advantageous alternative to the methods of non destructive testing (NDT) already existing. The strong probability of detection and especially the measuring accuracy of depth of the indications are there obviously for much. When the limits of the TOFD are reached, the traditional method of ultrasonics inspection can come in complement. The applicability is already rich: nuclear power with petrochemistry while passing by boiler making: for forgings, rolled, or of the pipes; one can use it within the framework of the quality control during the manufacture of engines, die spherical tanks, or of periodic inspections for the maintenance actions. The precise determination of the size of the defects makes it possible to follow their evolution well. But before going further in the possibilities than does the technique offers, how does it work?

Ultrasonic TOFD technology detection method for butt seam of different thickness plates

Abstract: An ultrasonic TOFD technology detection method for butt seam of different thickness plates comprises the following steps of: Step 1, placing an emission probe on the upper plane of a thick plate of a butt seam of different thickness plates and placing a reception probe on the upper plane of a thin plate of the butt seam of different thickness plates; Step 2, determining the probe angle and the probe spacing by means of a method same with that described in the traditional TOFD method; Step 3, allowing the emission probe to firstly generate an incident longitudinal wave with a certain angle in the thick plate; Step 4, ending with bottom echo; and Step 5, calculating the defect depth. The technical effects of the invention are as follows: the novel TOFD technology is adopted to inspect the butt seam part of different thickness plates with a new near surface creeping wave replacing the traditional creeping wave disappeared in the plane so as to realize identification and positioning of defects and widen the range of TOFD inspection objects.

Ultrasonic flaw detection apparatus and method

Abstract: PROBLEM TO BE SOLVED: To efficiently perform ultrasonic flaw detection by using a TOFD method. SOLUTION: When vertical scanning is performed by a TOFD method, at first, for example, four continuous ultrasonic vibrators 11 1 -11 4 among ultrasonic vibrators provided to an ultrasonic probe 11 are excited to generate ultrasonic waves. In the reception of these ultrasonic waves, four ultrasonic vibrators 12 n -12 n-3 among the ultrasonic vibrators provided to an ultrasonic probe 12 are used. Next, ultrasonic vibrators are shifted by one to generate ultrasonic waves in ultrasonic vibrators 11 2 -11 5 , and these ultrasonic waves are received by ultrasonic vibrators 12 n-1 -12 n-4 . Thereafter, flaw detection is performed while the ultrasonic vibrators are successively shifted one by one, and ultrasonic waves are finally generated by using ultrasonic vibrators 11 n-3 -11 n to be received by ultrasonic vibrators 12 4 -12 1 . COPYRIGHT: (C)1999,JPO

Ultrasonic flaw detection method and ultrasonic flaw detection apparatus

Abstract: PROBLEM TO BE SOLVED: To mitigate a constraint of an object, whose flaws can be detected by a TOFD (Time Of Flight Diffraction) method, in an ultrasonic flaw detection method SOLUTION: A transmitting oblique probe 11 for transmitting pulsed ultrasonic longitudinal waves to a scanned face 52 and a receiving oblique probe 12 for receiving the longitudinal waves of at least one of diffraction waves and scatter waves from an end of a defect on the scanned face 52 are disposed adjacent to a scanned face 53 on the same side as the scanned face 52 The transmitting oblique probe 11 transmits the ultrasonic longitudinal wave at an incident angle of 45° or smaller with respect to the scanned face 52 COPYRIGHT: (C)2004,JPO&NCIPI

Tofd inspection of v-groove butt welds on the hull of a container ship with a magnetically adhering wall climbing robot

Abstract: This paper presents the results of Time Of Flight Diffraction (TOFD) ultrasonic inspection of long welds on the hull of a container cargo ship. The TOFD probes are deployed by a low cost miniature climbing robot that adheres to the steel hull by using rare earth permanent magnets. 100% detection of defects sized larger than 0.6mm is obtained in V groove butt welds by a single pass scan. A scan and B scan results obtained by the inspection robot detect weld defects such as porosity, lack of root penetration and internal cracks.