Ultrasonic Sound
Uploaded by morg on Nov 25, 2008
CONTENTS
1.Introduction.…………………………………………………………………3
1.1 History………………………………………………………………3
1.2 Wave structure………………………………………………………3
2. Ultrasound.………………………………………………………………….4
2.1 Special features of Ultrasound …………………………………… .6
3.Sources of ultrasound………………………………………………………..6
3.1 Mechanical emitters…….…………………………………………...7
3.2 Electro-acoustic transducers………………………………………...8
4. Usage of ultrasound………………………………………………………..10
4.1 Ultrasonic cleaning….……………………………………………..10
4.2 Ultrasonic welding…………………………………………………10
4.3 Ultrasonic soldering and tin coating…………….…………………12
4.4 Production processes acceleration with the help of ultrasound……12
4.5 Ultrasonic flaw detection...........…………………………………...12
4.6 Ultrasound usage in radio electronicsî………………..……….…12
4.7 Ultrasound in medical treatment…………………………..……….13
5. Conclusion ………………………………....…………..……………13
1. Introduction
As long as ultrasound does not appear to be audible due to its high frequency bands the use of it in sound industry (music or film) is insignificant, though it is used for a huge amount of applications in science, industrial production and medical treatment. In this work I will analyze most common ways of ultrasound generation and investigate some ways of its usage .But let us first look how the history of ultra sound started.
1.1 History
The research of high frequency oscillations began in 1876, when a British physician Francis Galton generated high frequency sound waves with the help of a device which later was called “Galton Whistle”. Along with the flow of gas through a thin pipe high frequency oscillations emerged.
Pic.1 Galton’s Whistle
But the most significant discovery for the contemporary ultrasonic devices was generating oscillations in crystals with the help of electricity. In 1880 in Paris Pierre and Jacques Curie discovered piezoelectric effect- a production of electricity when applying mechanical pressure to certain crystals (Quartz or Rochelle salt); alternatively, electrostatic stress produces a change in the linear dimensions of the crystal. Piezoelectric crystals – is the fundamental of any contemporary ultrasonic device.
1.2 Wave structure
The physical phenomenon of sound waves is an example of oscillating process, and any kind of oscillation presumes deviation from balanced state and described with its characteristic digression from balanced values.
Sound represents mechanical vibrations of an elastic environment (solid, liquid or gaseous), which lead to creation of consistently alternating fields of compression and rarefaction so the same refers to ultrasound, though ultra sound has special features which are different from sound waves of audible range. It is easier focused due to its smaller wavelength and as a result you get an increase of intensity of ultrasonic oscillations. It was discovered that its propagation in gases, liquids and solid objects leads to different phenomena, the majority of which...