Excitation Reaserch Of Ultrasonic Resonance Thickness Measurement

Resonance is a method of ultrasonic thickness measurement. The thickness measurement of ultra-thin material, to a certain extent, dependents on the high frequency continuous ultrasonic excitation system, but with a conventional ultrasonic excitation, the frequency is several MHz or less in general. It is difficult to complete the measurement of ultra-thin material. There is an urgent need for a higher excitation frequency that can be used in the field of ultrasound. Conventional ultrasonic resonance thickness measurement method has a limit of 0.13 mm, which needs to be improved.In this context, we propose an improved method of thickness measurement of the resonance, and design a continuous high-frequency ultrasonic excitation circuit used here. Then we verify these two methods. Reads as follows:1. This paper first describes the background status and research significance of ultrasonic thickness measurement in NDT. Subsequently, we introduce the principle of ultrasonic thickness measurement method and compare their advantages and disadvantages. Then we decide to study the ultrasonic resonance thickness measurement. After this we propose an improved ultrasonic resonance thickness measurement method, aiming at improving the ability of ultrasonic resonance thickness measurement in the measurement of ultra-thin material. This designed thickness measurement system comprises: FPGA, DA converter, power amplification, the ultrasonic transducer, the sheet and the oscilloscope.2. This paper aims at the ultrasonic excitation system. Then we select an excitation, which is essentially a power amplifier circuit. Subsequently, we describe the classification, composition, analysis, frequency response, and safe operation of the power amplifier. Finally we choose class AB power amplifier with transformer-coupled to be used here.3. Focus on the designation of circuit schematic and PCB, we finally designed the power amplifier which can amplify the 2-15 MHz and 3.3V continuous sine wave with no distortion and its power can reach108 W.4. With oscilloscope and the Matlab, we get the excitation waveform and thickness measurement data. Thus we verified that the exciter can be successfully used in the revised ultrasonic resonance thickness measurement method. This revised ultrasonic resonance thickness measurement method has a high precision even when it meets ultra-thin material(such as 0.02mm).