Study And Realization Of Material Testing System Based On The Microwave And Ultrasonic

Fake and inferior products are internationally considered as the second biggestpublic hazard after narcotics. Now China has been the biggest production base of fakeand inferior products, it seriously impacts the security and stability of society. Aconvenient and nondestructive equipment is needed urgently by ordinary consumersand grassroots quality inspector to protect their and others’ basic rights.Due to the social need, know about various methods in nondestructive testingthrough consulting literature materials, and separately try to build up microwave andultrasonic test system. Design and separately build up microwave and ultrasonictesting system based on the fundamentals of microwave and ultrasonic. In the freespace, we use electromagnetic wave and mechanical wave to test material in differentfrequency bands through the ways of transmission and reflection. Find thecharacteristic frequency which could describe material property through analyzingreaction result between materials and two kinds of waves, build sample library andprovide reliable basis for the designing convenient and nondestructive equipment infuture.Microwave testing system is constituted by network analyzer E5071B andback-cavity helical antenna. In this subject, we use two pairs of antennas whichseparately cover the frequency bands200MHz2GHz and2GHz18GHz. At last,combined with the performance of network analyzer, we make sure the scan band is200MHz8.5GHz. We use transmission and reflection ways to test standard part ofmaterial. We should firstly find the rough scope of characteristic frequency throughrough scan (large stepped frequency), then get the accurate characteristic frequencythrough fine scan (small stepped frequency). According to the characteristic frequency,we can give qualitative judgment to material.Ultrasonic testing system is consisted with control part, emission part, receivingpart and ultrasonic sensors. Control part uses an industrial control board namedM2020-N20which is based on ARM7. In emission part, we use AD9850to productsinusoidal signals with various frequencies. In receiving part, it contains amplitudelimiting, multiple-way switch, gain amplification, rectifier&filter, AD converter and other parts. We choose5pairs of ultrasonic sensors to build up sensors array whichcan realize sweeping test, and the standard frequency of these5sensors are18KHz,23KHz,25KHz,32.8KHz and40KHz. Due to the performance of sensors, weset the sweep band to17KHz20KHz,21KHz24KHz,24KHz27KHz,30.8KHz34.8KHz, and38KHz42KHz. In these bands, we test the material’sstandard parts through the way of transmission stepped with50Hz. At last, we fit alltesting result to curves and find the characteristic frequency of material in the effect ofmechanical wave.We draw upon the basic theory of microwave and ultrasonic testing design andbuild up appropriate testing system to test several of materials in sweep frequency.Test result preliminarily proves the feasibility of testing system, and it constructs asolid basis to the further optimization.