MAGNETOSTRICTIVE SENSORS (MAGNETOSTRICTION)

 

What is magnetostriction?

Certain materials undergo a dimensional change when subjected to a magnetic field (magnetostriction). This change in dimensions occurs in the direction of the applied magnetic field and can result in elongation or shortening, depending on the material and the magnitude of the applied magnetic field.

magnetostriction

What happens if I combine magnetostriction and electricity?

If you wrap a coil around an iron bar and feed the coil with an electric current, the magnetic field it produces slightly lengthens the bar. A quick change of the current iron bar will vibrate in response. If you have ever heard a hum from a transformer, it is from this vibration.

 

The Villari Effect

The opposite effect also occurs. If you compress an iron bar in a vice, it will affect its magnetic properties. Scientists call this the Villari effect. A magnetostrictive material within a coil will change the electromagnetic properties of the coil as a function of the pressure and force exerted on the material. This is a type of magnetostrictive transducer called a force sensor.

Other sensors measure the speed of a sound pulse in a magnetostrictive cable. A permanent magnet near the wire puts a small twist on the wire when a current flows through it. If the magnet moves, the twist position moves with it. The sensor measures the time it takes for the sound pulse to travel from the twist to the end of the wire. The sensor is correct and works without friction and wear.

manestostriccion gif

Magnetostrictive distance sensors

Magnetostrictive distance sensors or magnet sensors, base their operation on the Villary effect, in which the magnetic field of a magnet intercepts a wave and this is reflected towards the electronics, so the round trip time is measured Of the signal. All this implies that it is a measure without friction.

the idea of ​​creating these posts is to make them as easy as possible in this case this topic is complex if you are interested in the topic and want to know how a sensor works I recommend entering the PDF from page 40 explains the operation of magnetostrictive sensors.