Magnetootpornički senzori u ispitivanju vrtložnim strujama

U radu je opisan mjerni lanac i fizikalna pozadina nerazornog mjerenja vrtložnih struja uz pomoć magnetootporničkih senzora. Izveden je mjerni lanac sastavljen od magnetootporničkih senzora, instrumentacijskih pojačala, visoko-propusnog filtra te pripadnog sustava za digitalnu akviziciju. Eksperimentalnim radom je provjerena primjenjivost magnetootporničkih senzora detekciji oštećenja različitih veličina na metalnim površinama vrtložnim strujama. Postignuta je osjetljivost od 0.125V/cm i omjer snaga signala i šuma od 38dB za oštećenje promjera 4cm. In this undergraduate thesis it is described how magnetoresistive sensors and eddy currents work. Moreover it is described how to make a system that uses magnetoresistive sensors for measuring eddy currents as an example of nondestructive testing (NDT). As a product of this work, a measurement chain was made that contained magnetoresistive sensors, instrumentation amplifiers, a high-pass filter and a relevant acquisition system. An experiment was conducted that had a goal to detect surface defects on a copper layer board using eddy currents. A sensitivity of 0.125V/cm was achieved with a signal to noise ratio of 38 dB for a defect with a diameter of 4 centimeters.