The accurate measurement of assembly fastening force of the high-pressure compressor rotor is of great significance to improve the structural connection quality and comprehensive performance of aero-engine. To solve the problem that liquid couplant reduces the measurement accuracy and causes the surface of the bolt to rust and corrode, a method of measuring the fastening force with dry-coupled ultrasonic wave was proposed in this paper. The measurement model of the fastening force including the thickness of the protective film of the ultrasonic transducer and the couplant was established, and the influence of the thickness variation in the couplant on the measurement accuracy of the fastening force was analyzed. Based on the propagation model of the ultrasonic wave on the heterogeneous interface and the principle of ultrasonic dry coupling, a coupling device was designed. At last, the experiment of fastening force measurement based on dry coupling and liquid coupling ultrasonic wave was carried out and compared. The experimental results show that the average relative errors of the fastening force measurement based on dry coupling and liquid coupling ultrasonic wave are 2.13% ± 0.42% and 3.15% ± 0.80%, respectively. Therefore, the dry coupling method can be as good or better in measuring the accuracy of the fastening force. Furthermore, it also overcomes the limitations of the liquid coupling method, which should make it more suitable to the measurement of fastening force in the aerospace field.

中文翻译：

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使用干耦合超声波测量紧固力

高压压气机转子装配紧固力的准确测量对于提高航空发动机的结构连接质量和综合性能具有重要意义。为解决液体耦合剂降低测量精度，导致螺栓表面生锈腐蚀的问题，提出了一种干耦合超声波测量紧固力的方法。建立了包括超声换能器保护膜厚度和耦合剂的紧固力测量模型，分析了耦合剂厚度变化对紧固力测量精度的影响。基于超声波在异质界面上的传播模型和超声干耦合原理，设计了耦合装置。最后，进行了基于干耦合和液耦合超声波的紧固力测量实验，并进行了比较。实验结果表明，基于干耦合和液耦合超声波的紧固力测量的平均相对误差分别为2.13%±0.42%和3.15%±0.80%。因此，干式耦合方法在测量紧固力的精度方面可以同样好或更好。此外，它还克服了液体耦合方法的局限性，使其更适用于航空航天领域的紧固力测量。实验结果表明，基于干耦合和液耦合超声波的紧固力测量的平均相对误差分别为2.13%±0.42%和3.15%±0.80%。因此，干式耦合方法在测量紧固力的精度方面可以同样好或更好。此外，它还克服了液体耦合方法的局限性，使其更适用于航空航天领域的紧固力测量。实验结果表明，基于干耦合和液耦合超声波的紧固力测量的平均相对误差分别为2.13%±0.42%和3.15%±0.80%。因此，干式耦合方法在测量紧固力的精度方面可以同样好或更好。此外，它还克服了液体耦合方法的局限性，使其更适用于航空航天领域的紧固力测量。