The accurate measurement of stress at different depths in the end face of a high-pressure compressor rotor is particularly important, as it is directly related to the assembly quality and overall performance of aero-engines. The ultrasonic longitudinal critically refracted (LCR) wave is sensitive to stress and can measure stress at different depths, which has a prominent advantage in stress non-destructive measurements. In order to accurately characterize the propagation depth of LCR waves and improve the spatial resolution of stress measurement, a finite element model suitable for the study of LCR wave propagation depths was established based on a wave equation and Snell law, and the generation and propagation process of LCR waves are analyzed. By analyzing the blocking effect of grooves with different depths on the wave, the propagation depth of the LCR wave at seven specific frequencies was determined in turn. On this basis, the LCR wave propagation depth model is established, and the effects of wedge materials, piezoelectric element diameters, and excitation voltages on the propagation depth of LCR waves are discussed. This study is of great significance to improve the spatial resolution of stress measurements at different depths in the end face of the aero-engine rotor.

The accurate measurement of the axial stress of the core engine rotor bolts is of great significance for improving the assembly quality and safety of aeroengines. To solve the problem that the thickness change of the coupling layer affects the measurement accuracy in ultrasonic measurement of axial stress, a measurement method based on time difference compensation of the thickness change of the coupling layer is proposed in this article. Based on the principle that different loads applied to the ultrasonic transducer will cause the thickness of the coupling layer to change, which leads to changes in the amplitude and propagation time of the ultrasonic echo signal, the principle of time difference compensation for changes in the thickness of the coupling layer is proposed. Based on this principle, the propagation time difference caused by the thickness change of the coupling layer is compensated, thereby improving the measurement accuracy of the propagation time difference caused by the stress and reducing the measurement error of the axial stress. The experimental results show that the average errors of the axial stress measurement model based on the time difference compensation of the thickness change of the coupling layer and the conventional axial stress measurement model are 1.048 and 1.723 MPa, respectively. Therefore, the time difference compensation for the thickness change of the coupling layer can effectively reduce the measurement error of the axial stress. This study provides a promising method for the accurate measurement of the axial stress of aeroengine bolts.

To suppress the vibration of rotary parts, this paper established an unbalanced vibration response control model of rotary parts based on rotating axis coordinate system. This model considered the stacking transformation of geometric parameter errors and mass parameter errors of single stage rotor. First of all, the centroid transfer model based on the actual rotation axis was established, and the unbalanced excitation force vector of each stage of the rotor was studied. Secondly, the unbalanced excitation force vector of each stage of the rotor is substituted into the model of assembly vibration control based on the double constraints optimization strategy. Finally, the simulation analysis and the vibration experiment of three-stage rotor stacking assembly is carried out. The results show that the vibration of the engine rotor can be effectively suppressed by adjusting the assembly phase of the rotors, and the vibration amplitude of the combined rotor assembled by the double constraint optimization assembly strategy is 22.5% less than the vibration amplitude assembled by the direct assembly strategy. Besides, the coaxiality and the unbalance are reduced by 44.1% and 78.4%, which fully shows the advantages of the double constraint optimization assembly strategy.

This paper proposes a blade sorting method based on the cloud adaptive genetic algorithm (CAGA), which is used to optimize the unbalanced of asymmetric rotor of aero-engine. Firstly, by analyzing the unbalance of the arrangement caused by the deviation of the mass moment of the blade, and considering the concentricity of the disk, an optimization model of the unbalanced amount of the blade assembly was established. Secondly, the selection operator, crossover operator, and mutation operator of the algorithm were designed, and the cloud adaptive genetic algorithm was used to optimize the assembly unbalance. Thirdly, the mass moments of a group of aero-engine blades were weighed using a moment scale (MW0), and the blade mass moment distribution and assembly unbalance under the six blade arrangements were analyzed. Finally, by setting different disk concentricity, the corresponding blade arrangement and the final rotor unbalance were obtained. Through analysis, it was found that the unbalance of GA is at least 57.5% optimized relative to the weight sorted, sorting type 2, sorting type 4, and sorting-1/4 skip method, and the unbalance optimized by the CAGA is 95.7% optimized relative to GA. In the case of different initial concentricity of the disk, the effective algorithm accuracy is still maintained, which proves the effectiveness of the method for the arrangement of asymmetric rotor blades. This method establishes an effective asymmetric rotor blade arrangement model, uses the cloud adaptive genetic algorithm to sort the blade assembly, and effectively reduces the unbalanced amount of the asymmetric rotor.

A dynamic analysis model of the unbalanced vibration response of a single-rotor system is established to study the corresponding mechanism of the unbalanced excitation force and vibration response caused by the deviation of the rotor mass centroid in this paper, and finally to achieve the combined rotor vibration suppression. First, the installation of multi-stage rotors during vibration was studied, and the rotor mass centroid transfer model in the rotating coordinate system was established to obtain the unbalanced excitation force vectors of the rotors at all levels based on the traditional stacking assembly method and axiality measurement. Second, the rotor unbalance excitation force vectors were substituted at all levels to establish the finite element analysis model of the single-rotor system. Finally, a simulation analysis was carried out for the stacking assembly of the three-stage rotor, and the rotor test piece was used for the vibration experiment. The results show that the optimal assembly phase of the multi-stage rotor obtained by the dynamic analysis model of the unbalanced vibration response of the single-rotor system can effectively suppress the vibration of the combined rotor.