提出了非接触空气耦合超声谐振法测量结构厚度的方案，将空气耦合超声波发射到测试体后，对构件中反复叠加产生的谐振信号进行傅里叶变换，求得频率，由频率与测试体厚度的关系式可以推算出测试体的厚度。从空气耦合探头向不同厚度的钢板发射超声波，通过谐振法对钢板进行了厚度测量，误差在0.2 mm以内。结果表明，不同厚度的测试体产生谐振的频率是不同的，超声谐振法可以准确地检出表面不同形状的缺损厚度。

In this paper, the non-contact air coupling method is proposed to measure the thickness of the structure. After the air coupled ultrasonic wave is transmitted to the test body, the frequency of the resonant signal is obtained by Fourier transform. The thickness of test body can be calculated from the relation between frequency and thickness of test body. Ultrasonic waves are transmitted from the air-coupled probe to the steel plate of different thickness. The thickness of the steel plate is measured by the resonance method, and the error is within 0.2 mm. The results show that the resonant frequency is different for different thickness test bodies. The defect thickness of different surface shape was detected accurately.