Applied Sciences

Mechanics of flow

Principle

The Doppler effect is used with ultrasonic waves to investigate the laws of stationary laminar flow, which underlie a great many technical applications. The liquid under investigation flows through a circuit of tubing. Particular aspects to be studied experimentally ...

Level measurement

Principle
For the experiment, a level measuring system for a two-phase liquid tank is set up and a calibration curve for the filling volumes is recorded. One task is to determine the minimum measurement volume ("dead band"). For maximum tank filling, an ultrasoni ...

Flow MeasurementUltrasonic Doppler effect

Velocity of ultrasound in solid state material

Principle

The velocity of sound in acrylics shall be determined by time of flight reflection technique with an ultrasonic echoscope. The measurements are done, by reflection method, on three cylinders of different length. Two measurement series are carried out with ultrasonic ...

Ultrasonic echography (A-Scan)

Principle

An ultrasonic wave transmitted in a sample will be reflected at discontinuities (defects, cracks). From the relationship between the time of flight of the reflected wave and the sound velocity, the distance between ultrasonic transducer and defects(reflector) can be ...

Ultrasonic echography (B-Scan)

Principle

The basic aspects of ultrasound B-scan techniques are illustrated by using an echoscope on a simple test object. This includes a discussion of some special aspects regarding image quality of ultrasound images, such as sound focus, spatial resolution image aberr ...

Angle beam measurement

Principle

The experiment demonstrates the application of ultrasonic angle beam probes in non-destructive testing. Echoes of transverse and longitudinal waves coming from an aluminium testblock are investigated using three different delay line angles. For straight beam probes, ...

Time of flight diffraction (TOFD)

Principle

The depth of the cracks of an aluminiumtest block with seven cracks ofdifferent depths (saw cuts) isdetermined with two methods. During theexperiment, the cracks in the materialare examined with the aid of theultrasound angle beam probe and thedepth of the cr ...

Detection of discontinuities

Principle

Various ultrasonic locating techniques are used on a test body with a variety of differing discontinuities. The body is first tested by scanning through it and an investigation is made to determine which techniques are best for detecting which types of faults. After ...

Frequency dependence of resolution power

Principle

An echoscope is used to measure two neighbouring faults in order to determine the differing axial resolutions of a 1-MHz and a 4-MHz ultrasonic probe. This will illustrate the relationships between wavelength, frequency, pulse length and resolution.

Attenuation of ultrasound in solid state materials

Principle

The attenuation of ultrasound in solid bodies (polyacrylic) is measured at three different frequencies using a reflection method and by scanning through the bodies with an echoscope. The results give an indication of how attenuation depends on frequency.

Shear waves in solid state materials

Principle

An echoscope is used to measure the emergence of longitudinal and transverse waves when sound passes through flat rectangular blocks made of differing materials. The relationship between amplitude and angle can be used to determine the speed of sound in the blocks i ...

Determination of the focus zone

Principle

A hydrophone is used to measure the amplitude of the sound pressure from an ultrasound probe along the axis of the sound transmission. The amplitude distribution is then used to find the length of the near field. In addition, the sound amplitude is measured at ...

Mechanical scan methods

Principle

A computer-controlled scanner is used to make a B scan of a test body using two probes of different frequency (1 MHz and 2 MHz) and various locating resolutions. A comparison is then made between the effects on the resolution capabilities.

Ultrasonic computer tomography

Principle

First an explanation of image generation using the CT algorithm is given. An attenuation and sound speed tomogram is then made on a simple test object and any differences are then discussed.