Abstract

Content

Input module


Output module


Oscilloscope


Examples shown on the V1 standard


Compare to praxis


Overview of all pictures

Introduction

In Ultrasonic testing, coupling shoes, usually made of Plexiglas, are used for flaw detection. The precise sound transmission through the specimen is often difficult to estimate, and only skilled personnel can easily obtain good results. USSIM (UltraSchallSIMulator) provides a tool to calculate the reflection and refraction at points where the sound beam travels through. Also it considers the acoustic impedance, and further calculates the sound transformation into transversal waves and presents the results as a graphic display. The program works on a standard PC-Dos, and provides a user-friendly Windows mouse interface.

Input module

The specimen enters this module as a two-dimensional drawing, possibly including defined flaws. The drawing tool includes lines, circles, and circle segments for definition of the specimen. The transducer can be positioned at any point around the specimen.


Input module

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Output module

The output module presents the specimen together with the calculated sound transmission. This is the most important menu of the program, and parameters can be changed until optimum sound transmission is achieved.
The position of the transducer (on the total surface of the specimen), and the angle (in 0,1degree steps) can be varied.
The A-screen is also shown as a small oscilloscope and sound-wave.
The sound beam is divided longitudinally, (green) and transversally, (violet). It is possible to select only longitudinal display, or how many reflections should be displayed. Due to fast processor capability each change of any of the parameters immediately changes the graphic display.

Output module
The program assumes the use of coupling shoes, and so defines a distance of 1 mm between transducer and specimen.

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Oscilloscope

After a simulation is finished it can be displayed as a result on the oscilloscope. A comparison with the praxis can also be done here.
The amplification of this oscilloscope is not the same as in commonly used flaw detectors
On the screen above the echoes a white line (for transversal echoes), and a yellow line (for longitudinal echoes), is displayed, allowing for easy differentation. Furthermore the scope has the capability to display the time of flight (Impulse-Echo-Technique).

Oscilloscope

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Examples at the V1 standard

Example 1
Impact straight on a large drill.
The appearance of pseudo-echoes is well displayed here, due to the large drill and the right border of the specimen.
Example 2
Impact straight on a small drill.
The Crystal diameter used here is in the same range as the small drill.
It shows clearly that the large drill will generate only a small echo.

Example 3
Longitudinal, transversal, and pseudo-echoes are clearly displayed.

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Comparison to Praxis

The simulated oscilloscope results compared with real measured results provide a good match. It is shown that this program, even though based on simplified sound wave theory, is useful for simulation of flaw detection.
The sound wave theory visualization also has great education potential.

The program rates high on accuracy. (refer to picture below). It should be noted that this simulation is based on a simplified method. The calculation is further limited to 77 beams for the complete real sound field. Good accuracy is obtained through considerable processor time.

Compare to praxis

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Overview of all pictures in this article

Here is an Overview of all pictures in this article