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.

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.

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.

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.

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.

To investigate the dynamic response characteristics and stability of a high in-situ stress roadway rock enclosures under blasting vibrations，the comprehensive gas management lane of Pan San Mine in Huainan is used as the engineering background. The research method of theoretical analysis of the blasting operation disturbing the roadway envelope rock model is established. Based on the stress wave propagation theory and the wave front momentum conservation theorem，the vibration equations for the roadway envelope under blasting vibration are derived. The theoretical analysis is then supplemented by the use of numerical simulation research methods from the perspectives of PPV （Peak Particle Velocity） attenuation characteristics and stress distribution patterns of the roadway envelope. The stability of the roadway envelope is analyzed based on the simulation results. Differences in the angle of incidence of blast stress waves lead to different dynamic response characteristics in different areas of the roadway envelope. These conclusions are drawn from the roadway envelope vibration equations. As the burst core distance increases，the PPV of the surrounding rock near the profile face of the roadway fluctuates and the maximum peak vibration velocity is obtained at the free face. In-situ stress has a suppressive effect on the PPV of the roadway envelope. The greater the ground stress is，the more obvious the suppressive effect will be. There are differences in the sensitivity of the PPV of the envelope to ground stress at different locations in the roadway. As the magnitude of the in-situ stress increases，the force state of the roadway envelope under blast vibration changes from tensile shear to compressive shear，and the maximum principal and shear stresses increase. The study reaches the conclusions that as the depth of burial increases，the ground stress factor cannot be ignored when assessing the stability of the tunnel envelope under blasting vibration. In addition to the straight walls of the roadway，the corners and arch walls are also hazardous areas that should be reinforced and monitored for the Pan San Mine project site.

The shaking table test of a half-cycle negative stiffness friction damping device with negative stiffness characteristics is carried out. Taking a four-floor steel structure frame as the seismic reduction research object，the half-cycle negative stiffness friction damping devices were arranged on the first and second floors of the steel structure frame respectively，and the seismic response of the structure under different ground motions was analyzed. The results show that the half-cycle negative stiffness friction damping device can control the acceleration and displacement response of the structure，and better seismic reduction effect can be obtained if it is arranged on the position with large structural deformation.

In order to seek a kind of tank structure which can absorb shock and reduce costs，a new structure system of isolation tank is proposed. The restoring force model of rolling isolation is deduced by the principle of balances of forces，and the restoring force model of composite rolling isolation device is obtained. Based on the three-particle model and site soil model，the simplified mechanical model and motion equations of the new isolation tank considering soil-tank-liquid interaction （STLI） are proposed，and the seismic responses of seismic tank and new isolation tank that considered STLI and Non-STLI are studied under different sites. The results show that the new isolation tank can effectively reduce the base shear and overturning moment，but the control of the sloshing wave height is limited. It is suggested that in the high intensity area，under the premise of meeting the shaking wave height，the new isolation tank can be designed to reduce the intensity. After considering the STLI effect，the base shear and overturning moment of seismic tank decrease obviously. The discrepancy rate gradually increases from class Ⅰ site to class Ⅳ site，and the decrease is most significant in soft soil. The seismic responses of the new isolation tank are less affected by the STLI，which can effectively cut off the coupling between the superstructure and the site soil，and weaken the influence of the STLI effect on the superstructure.

Aiming at reducing multi-dimensional vibration experienced by vehicle-mounted precise instrument，a multi-dimensional passive vibration isolator is built based on parallel mechanism with joint clearance. The 4-PUU parallel mechanism with axes 45° offset value，which exhibits three translations and one rotation characteristics is synthesized by G_F set type synthesis theory. The springs and viscous dampers are added on the active joints，meanwhile the kinematics and dynamics of the multi-dimensional vibration isolator are established. The vibration isolation capability with different values of joint clearance under harmonic and road random excitations is addressed. The results demonstrate that the proposed multi-dimensional isolator with joint clearance can inhibit multi-dimensional vibration in time and frequency domain significantly. As the value of joint clearance increasing，the vibration isolation capability degenerates，especially in x direction. Meanwhile，the first order resonance peak is sensitive to joint clearance，which shifts to low frequency range.

The vibration and noise of mechanical structures caused by transmission system is one of the key problems that need to be solved in the research of high-speed mechanical equipment. This study investigates the location and optimization of vibration and noise reduction of a high speed packaging machine transmission system based on coupling vibration and noise experiment and simulation analysis. The vibration and noise test device and the rigid-flexible coupling dynamic simulation model of the high-speed packaging machine's transfer mechanism and its transmission system is established. Based on the experimental data，the load identification is carried out and the accuracy and reliability of the model is verified. Based on the model，combined with modal participation factor and acoustic contribution analysis method，the modal frequency and plate area with large acoustic contribution of the high-speed packaging machine transmission system are analyzed，which improves and optimizes the design of the transmission system. The results show that modal contribution analysis and plate contribution analysis can locate the noise problem area quickly and accurately to serve the optimization of the corresponding mechanical structure design. The vibration and noise performance of the optimized high speed packaging machine drive system is improved significantly.

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.

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.

Compressed sensing can effectively relieve the burden of data storage and transmission for mechanical condition monitoring. However，this method exists some problems such as low compression efficiency and slow signal reconstruction process in the application of fault diagnosis. In this paper，using the corresponding relationship between autoencoder and compressed sensing，a novel fault feature extraction method of the rolling bearing in the compressed domain based on the deep convolutional measurement network is proposed. For the problem that noise-free fault signal samples are difficult to obtain，a dataset construction method based on the fault mechanism is proposed. The model trained on this dataset is suitable for bearing signals under different working conditions A deep convolutional denoising autoencoder （DCDAE） is constructed，in which the number of layers is determined by the required signal compression rate and the frequency of the hidden layer corresponds to that of the original signal. The fully trained encoding sub-network of DCDAE，named deep convolutional measurement network （DCMN），is used to compress the rolling bearing vibration signal instead of the traditional measurement matrix，and then the fault features are directly extracted in the compressed domain. The effectiveness of the proposed dataset construction method and the compressed domain feature extraction method are analyzed through the simulations. The rolling bearing experimental signals further verify that the deep convolutional measurement network trained by the proposed method has good generalization and can effectively extract fault features for fault diagnosis in the compressed domain with a compression ratio far lower than that of the traditional compressed sensing method.

A nonlinear two-degree-of-freedom system is used to construct an aircraft landing gear model. The stochastic excitation of the uneven runway to the system is described by time-domain noise，and the road roughness coefficient is used to describe the roughness of runway. Based on the probability density function and the statistics of system response，the influence of uneven runway on aircraft landing gear system is investigated. The reliability of the landing gear model and the passenger comfort under different road roughness coefficients are analyzed by establishing the relationship between the safety zones，comfort zones and the system response. The results show that the larger the road roughness coefficient is，the more fluctuation of the system state variable will be. The reliability and comfort of the system are negatively correlated with the road roughness coefficient. In addition，when the road roughness coefficient is small，the mean first-passage time and comfort of the system are more significantly affected by random disturbance. The present paper provides a theoretical basis for aircraft riding comfort and landing gear development and design.

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.

Considering the low accuracy problem of complex dynamic load identification under the effect of real measurement noise，an L1 norm regularized load identification method based on redundant extended cosine transform dictionary is proposed. According to the convolutional relationship between the system response and the external load，the discrete system control equation for load identification is established. According to the main characteristics of the vibration response signal，appropriate discrete cosine basis functions are selected and extended，and the extended cosine dictionary and the Db10 wavelet dictionary are used to cascade a redundant extended dictionary to represent the complex load sparsely. By using the L1 norm regularization method to solve the sparse representation vector under the proposed redundant extended cosine transform dictionary，the optimal regularization parameter is obtained by improved L curve criterion，and the identification of beat load and repetitive impact load at different noise levels is realized. The experimental verification results show that the constructed redundant extended cosine transform dictionary has much better performance in sparse representation of beat load and repetitive impact load，and the load identification method based on the redundant extended cosine transform dictionary has great advantages to obtain accurate inversion results and good robustness.

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.

To support the rapid and high-efficient elimination of the vibration fault of complex systems，this paper presents a quantitative method of vibration failure mode，which can realize the key verification of the vibration failure mode based on quantifiable value. The technical characteristics of the vibration fault tree analysis is discussed，which points out that fault tree analysis is not suitable for the vibration fault of complex systems. The quantification method of vibration failure mode is proposed，and dimensions of fault mode，like the probability of failure mode and the verifiability，are used to quantify. The vibration fault of the core machine of an aviation engine is introduced，and the specific application of the method of vibration failure mode is given. It proves that the quantization method of vibration fault mode has the availability，high efficiency，and the important value of the engineering application.