The blisks with mortise-tenon joints are widely used in modern aero-engines such as the fan, the compressor, and the turbine for the purpose of vibration attenuation, maintenance, and cost reduction. With the development of the modern aviation industry, key performance indicators such as high thrust-to-weight ratio, low fuel consumption, and high reliability are increasingly popular with aeronautical engineers thus resulting in a much harsher working environment such as high-speed, high-temperature, and high load for the rotating blisk. This can easily aggravate the severe stress concentration located at the tenon joint thus causing the blisk failure. Therefore, it is rather important to figure out their dynamic behaviors for engineering design and fault diagnosis purposes.
Numerous literature on the dynamic characteristics of the blisk with mortise-tenon joints has been published. Ma et al. [
1] utilized the un-reduced three-dimensional finite element model of a single blisk sector with the tenon-mortise joint structure to study the effects of rotating speeds and penetration depths on the corresponding rubbing characteristics. Quaegebeur et al. [
2] adopted the component nonlinear complex mode synthesis method integrated with the dynamic Lagrangian frequency time algorithm to analyze the effects of friction factor, rotating speed, and traveling/standing wave excitation on the amplitude-frequency responses of an industrial blisk with the tenon-mortise joint structure. Li et al. [
3] used the plane beam elements to simulate the in-plane flapwise vibration of a mock blade with a dovetail structure and analyzed the effects of rotating speed, friction factor, and excitation level on the amplitude-frequency curves and hysteretic characteristics of the system. In their later works [
4], the incremental harmonic balance method combined with a linearization method of friction was adopted to analyze the nonlinear dynamics of the model in Ref. [
3]. Considering the bending-bending-axial coupling vibration of a pre-twisted blade, She et al. [
5] expanded the single blisk sector in Refs. [
3,
4] to the whole blisk, and investigated the corresponding eigenvalues of veering and merging phenomena. Shangguan B et al. [
6] investigated the dynamic responses of a compressor blade with dovetail attachment under different rotating speeds from an experimental point of view, and the experimental results showed the existence of an optimal centrifugal force causing the minimal resonant amplitude and best damping effect. In their later works [
7], a fractal contact friction model was introduced to describe the friction force situated at the tenon-mortise contact surfaces, and the multi-harmonic balance method combined with Newton iterative algorithm was used to analyze the nonlinear vibration responses of a loosely assembled blade with dovetail root. Using the one-way coupled and harmonic balance methods, Lassalle and Firrone [
8] investigated the limit cycle oscillations of a blisk with dovetail structure caused by flutter and friction. Zucca et al. [
9] developed a refined version of the state-of-the-art contact model to simulate the microslip between the blade and the disk contact surfaces and evaluated their effects on the forced responses of a blisk. Appaji et al. [
10] investigated the stress state at the contact interface of a dovetail blisk attachment for varying friction factors and rotating speeds, and the results showed that the peak stress decreased with the increasing friction factor. Chen et al. [
11] built the two- and three-dimensional finite element models of both simplified and realistic blade-root structures and discussed the effects of contact interface parameters, contact interface geometry, and various loading conditions on the hysteresis characteristics. In their later works [
12], the high-fidelity calculation of modal damping at root joints for a lone blade as well as for a tuned blisk was performed. Using the lumped-parameter model with dry friction nonlinearity between the blade root and the disk to simulate the fundamental sector of a blisk, Joannin et al. [
13] studied the forced responses and nonlinear complex modes for a tuned system under different excitation levels and for a mistuned system under random stiffness mistuning and different excitation levels. Schwarz et al. [
14] carried out the nonlinear experimental modal analysis, which verified the phase-resonant method to isolate nonlinear modes in accordance with the extended periodic motion concept and the extracted nonlinear modal frequency and damping ratio in good agreement with the near-resonant frequency response tests. Based on the lumping parameter model of a single blisk sector subjected to dry damping under harmonic excitation, Liu et al. [
15] used a multi-harmonic method combined with a continuation procedure to investigate the effects of excitation level, tangential stiffness of friction model, and normal contact force on the steady vibration responses of the system. For the purpose of prediction of the residual life, Canale et al. [
16] adopted the commercial software FRANC3D to analyze the low cycle fatigue crack propagation of a rotating blade with a dovetail structure, and the results showed 45° with respect to 30° and 60° flank angles and a lower friction factor resulting in a lower crack propagation rate. Yuan et al. [
17] investigated a novel adaptive reduced order modeling method to reduce the high-fidelity fan blisk with dovetail joints and then analyzed the nonlinear modal characteristics under different friction factors and pre-loadings. Anandavel et al. [
18] performed an analysis of the effects of preloading at the dovetail interface on the contact tractions, slip levels, and contact stress distribution for a single blisk sector, and the results indicated that the preloading effect was beneficial to reducing the peak contact pressure and stress difference between top and bottom contact edges. Fernandes et al. [
19] investigated the change rules of stress intensity factors
KI,
KII, and
KIII varying with crack width for both a single blade and a blisk using commercial software ANSYS and FRANC3D, and analyzed the corresponding natural frequency changing with crack size and rotating speed. Wei et al. [
20] used the finite element method to study the variation of the contact state in a dovetail attachment and pointed out the movement of the contact edge dominated by the relative slip and compaction of the tenon-mortise joint.
From the literature listed above, it can be concluded that most research focused on the analysis of the contact properties, hysteresis behavior located at the contact region, and modal characteristics of a single blisk sector with a dovetail structure, however, less attention is paid to the nonlinear vibration features caused by the tenon-mortise joint, which can be rather helpful to realize the on-line monitoring and fault diagnosis. In addition, a macroslip model to describe the contact behaviors between the tenon and the mortise is relatively inaccurate especially when quantitatively analyzing the dynamic characteristics of the rotating blisk with a dovetail structure. In order to make up for the existing deficiencies, a single blisk sector with a dovetail structure is taken as an example, whose three-dimensional finite element model is built via the solid and contact elements. Then the fixed-interface component mode synthesis method is adopted to establish the reduced blisk sector model, and the corresponding availability is verified via the frequency convergence and vibration mode analysis. Next, the effects of rotating speed and friction factor on the nonlinear dynamic characteristics of the reduced model under the action of aerodynamic force are elaborately discussed. Finally, some conclusions are made.