The braking torque of the carbon ceramic braking system of the landing gear increases with the reduction of wheel speed under the condition of rapid change of angular speed. The negative slope of the braking torque and wheel speed curve has a great relationship with the landing gear walking vibration. Focusing on the impact of the negative slope of the braking torque on the landing gear brake vibration，a three degree of freedom landing gear brake walking model is established，and the main landing gear brake vibration of amphibious aircraft is analyzed. The calculated acceleration response and frequency are consistent with the test results of the landing gear field skid brake test. The effects of initial braking torque，negative slope，landing gear heading stiffness and damping，strut equivalent height and other parameters on the landing gear dynamic system are studied，and the dual parameter vibration convergence boundary of initial braking torque and negative slope of braking torque under high speed braking is given. By means of Hopper bifurcation analysis，the two parameter stability boundary of the negative slope of braking torque and velocity under the global state of the landing gear system is given. Through analysis，it is concluded that the gear walk may be caused by two reasons： the negative slope of the braking torque exceeds a certain range，or the braking torque is too large due to large braking pressure，and the slip ratio exceeds the limit. Compared with high speed braking，the negative slope of braking torque has greater influence on the stability of low speed braking. Finally，based on the analysis results，the methods and suggestions to improve the gear walking vibration of landing gear are given.

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.

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 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.

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.

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.

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 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.

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.

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.