In this paper, the SiC/SiC high-pressure turbine twin guide vanes were fabricated using the chemical vapor infiltration (CVI) method. Cyclic thermal shock tests at different target temperatures (i.e., 1400, 1450, and 1480 °C) in a gas environment were conducted to investigate the damage mechanisms and failure modes. During the thermal shock test, large spalling areas appeared on the leading edge and back region. After 400 thermal shock cycles, the spalling area of the coating at the basin and back region of the guide vane was more than 30%, and the whole guide vane turned gray, due to the formation of SiO₂. When the thermal shock temperature increased from 1400 to 1450 and 1480 °C, the spalling area of the basin and the back region of the guide vane did not increase significantly, but the delamination occurred at the tenon, upper surface of the guide vane near the trailing edge of the guide vane. Through the X-ray Computed Tomography (XCT) analysis for the guide vanes before and after thermal shock, there was no obvious damage inside of guide vanes. The oxidation of SiC coating and the formation of SiO₂ protects the internal fibers from oxidation and damage. Further investigation on the effect of thermal shock on the mechanical properties of SiC/SiC composites should be conducted in the future.

As one of the critical components in helicopter transmission systems, the flange is prone to fatigue damage and failure under complex operational conditions, which seriously influence operational safety and service life. To improve the structural integrity of flanges, an exponential distribution optimizer (EDO)-based integrated surrogate model (ISM) method is proposed for the fatigue life prediction and reliability evaluation of the flange structure. In this method, the Bayesian model averaging method is adopted to build a high-efficient surrogate model and the EDO is used to find the optimal parameters of the model. The high cycle fatigue (HCF) life prediction and reliability evaluation of the helicopter flange structure are performed by the proposed EDO-ISM method and other methods. Results demonstrated that the EDO-ISM method improves modeling precision by 63.17% and computational efficiency by 8.743%, relative to other methods. The reliability analysis shows a high reliability degree of 0.9981 for the flange structure, while sensitivity analysis reveals that rotational torque (S = 0.386, I = 0.312) and the fatigue ductility index (S = 0.312, I = 0.278) are the most significant parameters affecting the flange HCF life. These results reveal the strengths of the EDO-ISM method in the HCF life prediction and reliability evaluation of the helicopter flange structure. The efforts of this study provide a promising method for the HCF life prediction and reliability evaluation of complex structures besides helicopter flanges under complex working conditions.

In this paper, the 12k T-700^TM Multiaxial-Warp-Knitting–Needle (MWK–N) C/SiC composite and pin were designed and fabricated using the isothermal chemical vapor infiltration (ICVI) method. The composite’s microstructure and mechanical properties were examined by subjection to tensile and interlaminar shear tests. Three types of double-shear tests were conducted for C/SiC pins, including shear loading perpendicularly, along, and at 45° off-axial to the lamination. The fracture surface of the tensile and shear failure specimens was observed under scanning electronic microscope (SEM). The relationships between the composite’s microstructure, mechanical properties, and damage mechanisms were established. The composite’s average tensile strength was σ_uts = 68.3 MPa and the average interlaminar shear strength was τ_u = 38.7 MPa. For MWK–N–C/SiC pins, the double-shear strength was τ_u = 76.5 MPa, 99.7 MPa, and 79.6 MPa for test types I, II, and III, respectively. Compared with MWK–C/SiC pins, the double-shear strength of MWK–N–C/SiC pins all decreased, i.e., 26.7%, 50.8%, and 8% for test types I, II, and III, respectively. The MWK–N–C/SiC composite and pins possessed high interlaminar shear strength and double-shear strength, due to the needled fiber in the thickness direction, low porosity (10–15%), and high composite density (2.0 g/cm³).

Reliability analysis of aeroengine structures is a critical task in aerospace engineering, but traditional methods often face challenges of low computational efficiency and insufficient accuracy when dealing with complex, high-dimensional, and nonlinear problems. This paper proposes a novel reliability assessment method (AC-Kriging) based on the Actor–Critic network and Kriging surrogate models to address these issues. The Actor network optimizes the sampling strategy for design variables, making sampling more efficient. The Critic network assesses the reliability of these samples to ensure accurate results, while a Kriging surrogate model replaces expensive finite element simulations and cuts computational cost. Three case studies demonstrate that AC-Kriging significantly outperforms traditional methods in both sampling efficiency and reliability estimation accuracy. This research provides an efficient and reliable solution for reliability analysis of aeroengine structures, with important theoretical and engineering application value. Three case studies demonstrate that AC-Kriging significantly outperforms traditional methods in both sampling efficiency and reliability-estimation accuracy, requiring only 52–147 samples to achieve comparable accuracy while maintaining the relative failure probability error within 0.87–7.27%. This research provides an efficient and reliable solution for the reliability analysis of aeroengine structures.

In composites, fiber–matrix thermal mismatch induces stress heterogeneity that is beyond the resolution of macroscopic approaches. The asymptotic expansion homogenization method is used to create a multi-scale thermo-mechanical coupling model that predicts the elastic modulus, thermal expansion coefficients, and thermal conductivity of ceramic matrix composites at both the macro- and micro-scales. These predictions are verified to be accurate with a maximum relative error of 9.7% between the measured and predicted values. The multi-scale analysis method is then used to guide the vane’s thermal stress analysis, and a macro–meso–micro multi-scale model is created. The thermal stress distribution and stress magnitudes of the guide vane under a transient high-temperature load are investigated. The results indicate that the temperature and thermal stress distributions of the guide vane under the homogenization and lamination theory models are rather comparable, and the locations of the maximum thermal stress are predicted to be reasonably close to one another. The homogenization model allows for the rapid and accurate prediction of the guide vane’s thermal stress distribution. When compared to the macro-scale stress values, the meso-scale predicted stress levels exhibit excellent accuracy, with an inaccuracy of 11.7%. Micro-scale studies reveal significant stress concentrations at the fiber–matrix interface, which is essential for the macro-scale fatigue and fracture behavior of the guide vane.

This study investigates the stiffness characteristics of elastic ring supports and the dynamic response of aero-engine rotor systems. First, comparative analysis demonstrates that the finite element model provides higher accuracy in predicting the stiffness of the elastic ring compared to traditional analytical methods, with the experimental error controlled within 5%. Grid independence verification further reveals that the mesh density in the boss region is a critical factor determining the accuracy of stiffness calculations. On this basis, the influence mechanism of contact states on stiffness characteristics was deeply explored; it was found that the transition between frictional and bonded contact states can lead to a stiffness deviation of up to 46.8%. Furthermore, quantitative analysis of manufacturing tolerances indicates that the thickness deviation of the boss should be strictly controlled within 0.02 mm to ensure the stability of support performance. Finally, a dynamic model of the rotor system developed using two-dimensional beam elements was fully validated against experimental data, with a calculation error of only 2%. The results of this study provide an important reference for the precise design and stiffness evaluation of elastic ring supports, as well as the engineering testing of rotor system dynamic characteristics.