Abnormal vibration often occurs in the liquid oxygen kerosene transmission pipeline of the rocket engine，which seriously threatens the safety of the rocket engine. Improper handling will result in a failed rocket launch and enormous economic losses. Therefore，it is necessary to study the vibration of the transmission pipeline. In this paper，a three-dimensional high pressure transmission pipeline model comprising a corrugated pipe，a multi-section bending pipe and other auxiliary structures is established.Using the two-way fluid-solid coupling method，the vibration analysis of the pipeline is performed under external pressure pulse excitation. The accuracy of the computation results is verified by a thermal test. The results show that at the same frequency，the amplitude distribution of vibration acceleration obviously correlates with the amplitude distribution of flow field pressure，which indicates that the fluid pressure fluctuation is the root cause of abnormal vibration of pipeline.And the vibration of pipeline increases with the increase of average pressure. In the visualization results，the location of pipeline vibration is mainly concentrated in the middle pipeline and bellows. The stress and strain of the pipeline are concentrated at the bellows，bends and supports，which is different from the distribution of vibration acceleration. The position with large stress and strain is the dangerous position where the structure is prone to failure，which should be paid more attention to.

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.