to ensure the soundness of the weld is use of DGS scales in Ultrasonic testing. order to bring the 3mm diameter disc on to curve II) then one uses the lines. Physics of NDT made clear by simulation · Ultrasonic Testing for Education · Eddy DGS (Distance Gain Size) or AVG (Abstand Verstaerkung Gröesse – in german) curves from manufacturer (Krautkrämer) are compared to simulation data for. block method the characteristic curve of the sound field is always determined before carrying out an ultrasonic test, whereas in the DGS method DGS diagrams.

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Ultrasonic Flaw Detection Tutorial. For each hole, the maximum amplitude of the specular echoes of the FBH is measured relatively to a calibration hole. The input signal frequency is 2. If the ranges of the backwall and the disc reflector are different, then attenuation shall be accounted for separately.

DGS/AVG | Olympus IMS

This notice describes the privacy policy of bindt. These are called the ultrasonicc echo curves, and are used to set the correct sensitivity from the backwall. Please select the activities you want to receive information about: Material attenuation and coupling variation in the calibration block and test specimen can be accounted for.

It is always up to the user to determine how the resultant DGS calculations relate to actual flaws in real test pieces. In the example below, the upper curve represents the DGS plot for a 2 mm disk reflector at depths from 10 mm to 50 mm. In the screen at left, the red gate marks the reflection from a 2 mm diameter flat bottom hole at approximately 20 mm uultrasonic.

The uppermost curve represents the relative amplitude of the echo from a flat plate reflector in decibels, plotted at various distances from the transducer, and the curves below represent the relative amplitude of echoes from progressively smaller disk reflectors over ultrasnoic same distance scale. Frequency Crystal Mode Calibration flaw Calibration depth 1.


When this concept was first established, the general DGS diagram was developed as shown below:. If you do not change your web settings, cookies will continue to be used on this website.

UT – FBH: DGS curves

Part Three Training Ckrve Information about our customers is an important part of our business and we are not in the business of selling it to others. These types of scales are made specifically for a particular probe the B4S — 4 MHz, 24 mm diameter zero compression probe and shows a characteristic curve for 6 currve, 4 mm and 3 mm reflectors.

Specific DGS curves for individual probes can be produced and so both the distance axis and the reflector sizes can be in mm. The interaction model is the Kirchhoff model which is well suited to specular echoes. Aerospace Event About the event Information for Exhibitors CM About the conference Abstract and full paper submission Registration Key dates and participation Keynote speakers and structured session ultrasoniic Exhibitors booking form Venue and accommodation Sponsorship packages Travel information Travel and attendance ucrve Best student paper award About the organisers List of sponsors.

Since this reflector equals the selected registration level, the peak matches the curve at that depth. From that one calibration point, an entire curve set can be drawn based on probe and material characteristics.

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For small FBH above the focal spot the difference is up to 6 dB. At shorter beam paths, set the backwall to RE1 and add 16 dB, then read the equivalent flaw sizes directly from the screen.


Index of acronyms D DGS. Part Two Training Courses: Back to Calibration defects.

The curves show a good agreement between simulated and experimental data for FBH deeper than the focal depth. In the screen at right, a different reflector at a depth of approximately 26 mm has been gated. Continue to Conclusion and discussion about the limitations.

DGS scales are specific to each probe specification and test range. Home Ultrasonic Flaw Detection Tutorial 8. Based on its height and depth in relation to the curve the instrument calculated an ERS of 1.

At longer beam paths, set the backwall to RE2 and add 8 dB. Consider a probe scanning over three similar discontinuities of different sizes:. The measurements have been made with the following contact probes:.

The lower curve is a reference that has been plotted 6 dB lower. Rather than plotting the entire curve set, instruments will typically display one curve based on a selected reflector size registration level that can be adjusted by the user.

Reflectors of different size, at the same beam path distance, will have an echo height proportional to their area, assuming that the reflectors are in the far ultrasoic. A 6 mm disc should have an amplitude 4 times that of a 3 mm disc.

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UT – FBH: DGS curves

This of course assumes that the reflectors are in the far zone and are smaller than the beam diameter. This is not realistic, so the final modification to the DGS scales is to include a characteristic curve for a backwall reflection. The input signal frequency is 1.