The flexible structure in probe-drogue aerial refueling system often occurs the hose whipping phenomenon in different degrees，which greatly affects the safety of aerial refueling mission. Based on flexible multibody dynamics，a dynamic model of aerial refueling system is built. The large deformation，large-scale movement and variable length characteristic of the hose are described by beam element that based on arbitrary Lagrange-Euler description and absolute node coordinate method. The aerodynamic model on the aerial refueling system is built，which can reflect the coupling effect between the movement of the tank and the receiver，the deformation of hose and aerodynamic force. Based on the dynamics model，the hose whipping phenomenon in flight is reproduced，and the formation mechanism of the phenomenon is obtained. The research shows that the docking impact is the main cause of whipping phenomenon，which changes the equilibrium state of the hose and causes shear waves to propagate and reflect back. The results of multi-case simulation are used for analyzing the influence law of various factors，including hose stiffness，docking speed and Mach number，on the shear force，longitudinal wave and shear wave propagation speed of the hose when whipping phenomenon happened. The effectiveness of hose reeling in/out control and buffered probe for vibration suppression of hose whipping phenomenon is also analyzed，which provides an important reference for improving the safety of probe-drogue aerial refueling system.

A simplified model for free vibration analysis of functionally graded plates is proposed based on higher-order shear deformation theory，the most significant feature of which is that it applies for the vibration analysis of functionally graded plates without any shear corrections. Compared with other shear deformation theories that contain more unknown variables，this model contains only one control equation，and thus greatly reduces the computational cost. Based on this simplified model，the free vibration of functionally graded rectangular plates with simple support boundary conditions is investigated and compared with other existing literature. The results show that the simplified model proposed in this paper is simple and accurate in solving the free vibration behavior of functional gradient plates. In addition，the effects of different gradient indices，aspect ratios，and length-thickness ratios on the free vibration behavior of functionally gradient plates are analytically discussed in the paper by several numerical arithmetic examples.

The steady-state and transient vibration responses of a medium thick hemispherical shell are obtained based on semi-analytical method. According to the first-order shear deformation theory，the energy expression of the spherical shell structure is deduced. The Jacobi orthogonal polynomials and Fourier series are introduced to represent the axial and circumferential displacements of the hemispherical shell structure. The steady vibration response of the hemispherical shell is obtained by Ritz method. The results are compared with the finite element method to verify the feasibility of the presented method in this paper. On this basis，the characteristics of steady and transient vibration of the hemispherical shell under different boundary conditions，truncated angle and shell thickness are summarized and analyzed.

The additional tuning mass damper is a traditional control technique for the chimney，but it usually requires a large additional tuning mass and auxiliary installation space，which brings inconvenience to the construction and installation. This study proposes utilizing the additional tuned mass inerter system （TMIS） to reduce seismic responses of the chimney. The apparent mass effect of the inerter is employed to achieve the goal of lightweight control. Meanwhile，considering that the influence of high-order modes of the high-rise chimney on its seismic responses cannot be ignored，the distributed TMISs arranged along the height of the chimney are proposed to achieve the multimode control effect. Mechanical models of the TMISs based on two different inerter subsystems are established，and the equations of motion for the chimney with corresponding additional distributed TMISs are established. Taking Kanai-Tajimi’s spectrum as the random seismic excitation input and based on the extended fixed-point theory，the simplified assumptions for part of the design parameters of distributed TMISs are proposed. The demand-oriented multimode optimization design method for the chimney with distributed TMISs is presented. The effectiveness of the proposed design method is verified by a design case. The lightweight and multimode control effects of additional distributed TMISs are examined by comparative analyses. The rationality of the simplification based on the extended fixed-point theory is verified through parameter analysis. The results show that the proposed design method can achieve the expected target performance using the two distributed TMISs. Both the two distributed TMISs behave obvious lightweight control effect.

Multi-axial stationary non-Gaussian random vibration control tests can simultaneously control the time-frequency characteristics of the specified response signals. A fast method for generating stationary non-Gaussian random vibration signals with specified power spectral density，skewness and kurtosis is proposed. The target power spectral density is designed as a filter by frequency sampling method. The non-Gaussian random signal is obtained by nonlinear transformation method and then it passes through the designed filter to obtain the desired non-Gaussian random signals. This method is computationally efficient and overcomes the shortcoming of the traditional nonlinear transformation methods. This proposed method is applied to the three-axis stationary non-Gaussian random vibration test，and the closed-loop equalization step of the three-axis non-Gaussian random vibration control is given，which can decouple the power spectrum auto spectrum，coherence coefficient，phase difference，skewness and kurtosis of the signal at the same time. A three-axis stationary non-Gaussian random vibration control test is carried out. The control results of power spectral density，skewness and kurtosis in three directions are satisfactory which meet the requirements of engineering application.

Oscillating underwater flexible structure actuated by smart materials are widely used in the fields of robotic fish，autonomous underwater vehicle，precision medical instrument，and so on. In this paper，the nonlinear hydrodynamics of an underwater Macro Fiber Composite （MFC）-actuated flexible cantilever undergoing large amplitude vibration is studied. The fluid-structure coupled dynamic equation of the proposed structure is established. Parametric 2D CFD studies of the proposed structure at different characteristic frequencies and amplitudes are performed. The distribution and evolution of the flow field in the vicinity of the vibrating structure are revealed. CFD results show that the vortex shedding，diffusion and convection phenomena which are responsible for the nonlinear hydrodynamic damping effect appear as the vibration amplitude increases. Then，a manageable expression for the revised hydrodynamic function governed by the interplay of the characteristic frequency and vibration amplitude is presented to model the hydrodynamic load exerted on the flexible structure undergoing finite amplitude vibration. The imaginary part of the revised hydrodynamic function which accounts for the hydrodynamic damping effect decreases with the characteristic frequency for the small amplitude vibration. It first decreases then increases for the finite amplitude vibration，exhibiting a strong nonlinear behavior. Experimental results show that the measured frequency response spectrums of the proposed structure undergoing finite amplitude match well with the predicted results of the developed model. Thus，the validities of the developed hydrodynamic function and fluid-structure coupled dynamic equation are demonstrated.

Under the action of strong seismic excitations，structures exhibit time-varying dynamic characteristics due to damage. Variational mode decomposition （VMD） can be used to analyze the instantaneous frequency variation of structural seismic responses and reveal the damage condition of structures during earthquake. When VMD is adopted for decomposing the non-stationary responses，there exists the problem of mode aliasing due to the artificially presetting the number of decomposed modes K and the quadratic penalty factor α. Aiming at solving this problem，an improved variational mode decomposition （IVMD） algorithm is proposed in this study，which，combined with Hilbert transform （HT），can more accurately identify the instantaneous frequencies of time-varying structures under non-stationary seismic excitations. The multiple signal classification （MUSIC） algorithm is used to determine the number of decomposition modes K. The comprehensive objective function is constructed based on the overall orthogonal coefficient and energy ratio coefficient，and the slap swarm algorithm （SSA） is used to optimize and determine the optimal quadratic penalty factor α. Based on the optimized parameters K and α，IVMD-HT is used to identify the instantaneous frequency of time-varying structures from the seismic responses. A simulated signal and the seismic responses of a 4-layer time-varying frame structure show that the accuracy of identified instantaneous frequencies by using the IVMD algorithm is higher than the identified ones by using the VMD algorithm. The feasibility of the proposed method is verified by using shaking table test data of a 12-story reinforced concrete frame structure model.

Based on the finite element software ANSYS Workbench，the finite element model of the foil gas bearing movement in compressible fluid medium is established，and the fluid-structure coupling numerical simulation of the bearing movement state is carried out by using the 6DOF dynamic grid calculation method. The influence of different speed and wave foil structure parameters （length ratio，height and thickness of wave foil） on dynamic characteristics of bearing is discussed. The simulation results show that with the increase of rotational speed，the bearing capacity increases，but the stability decreases，and the instability phenomenon is more likely to occur. When the length ratio is between 1~1.5 and the thickness is 0.16 mm，it can not only ensure the high stiffness of the bearing，but also obtain large damping. The height of wave foil is inversely proportional to the dynamic characteristics of bearing. The simulation results are compared with the experimental results to verify the correctness and effectiveness of the simulation calculation method. Meanwhile，the research of this paper provides a theoretical basis for optimizing the wave foil structure，improving the dynamic characteristics of bearings and improving the stability.

The fault diagnosis method based on deep learning is widely used in the fault diagnosis of key mechanical components represented by bearings. The premise of achieving ideal results is that there are enough fault samples and the training set and test set meet the same distribution requirements. However，the data distribution will change under the actual working conditions，which makes it difficult to apply the diagnostic model under the original working conditions to the new working conditions. For this reason，the domain adaptation transfer learning method is used to solve the problem of different distribution of training sets and test sets，and its key point is to achieve data distribution adaptation，that is，to measure data distribution differences and use the measurement results to guide model training，which can effectively improve learning efficiency and diagnostic accuracy. On this basis，this paper proposes a new domain adaptation method based on adversarial learning. The core of this method is to combine the proposed exponential adjustment strategy with adversarial network to make the network adapt to different data distribution in source domain and target domain more specifically in the process of fault diagnosis. The network consists of a feature extractor，a classifier，a global domain discriminator，and multiple local domain discriminators，and the model is optimized by using the adversarial strategy and adaptive moment estimation algorithm，and adjusted the importance of marginal distribution and conditional distribution by using the exponential adaptive factor set based on the exponential adjustment strategy，so that the model could diagnose faults stably and efficiently. The proposed method is verified in bearing diagnosis cases of cross-speed，cross-load and simultaneous cross-speed load. The results show that the method in this paper is better than other domain adaptation methods in diagnosis effect and has better stability.

In order to satisfy both cushioning and fast-extension performances，the carrier aircraft nose landing gear often adopts the dual-chamber buffer design. Based on a certain type nose landing gear，this paper establishes the dynamic model of the cushioning performance analysis and compares the simulation calculation results with the test results to ensure the validity and correctness of the theoretical dynamic model. The parameter sensitivity analysis of cushioning performance is carried out for the initial filling pressure and volume ratio of the high- and low-pressure chambers of the buffer. Results show that the effects of the initial filling pressure and high- and low-pressure chambers volume ratios on the cushioning performance is different from their impacts on the fast-extension performance. Therefore，the design of the nose landing gear buffer of the carrier aircraft needs to be continuously optimized for taking the cushioning and fast-extension performances into account synchronously.