Impact load is a common load，but it is also very special. Compared with other persistent loads，impact load has the characteristics of short duration and large output energy，leading to the transient vibration which may affect the system’s operation safety. In this paper，the active magnetic bearing （AMB）-flexible rotor was installed on an elastically supported base. The vibration characteristics of the elastic supported base under five types of impact loads，including double half-sine wave，half-sine wave，sine wave，triangle wave，and double triangle wave，were investigated. The influence of different impact load parameters on the acceleration of the base was obtained. In order to suppress the rotor vibrations，relative to the base induced by impact loads，a transient vibration compensation control strategy based on the base acceleration was derived. The theoretical and experimental results indicate that the elastic supported base and the AMBs-flexible rotor system installed on it both exhibit obvious impact characteristics under impact loads. These impact characteristics vary with different types of impact loads. The effect of base shock excitations on the rotor vibration can be effectively suppressed by the proposed algorithm.

Aiming at the issue of inter-shaft bearing waviness in a dual rotor system，the dual rotor-bearing system of external rotor with variable cross section was taken as the research case. The dynamic model of the dual rotor-bearing system was established based on the Finite Element Modeling （FEM）. The waviness of the inner and outer ring raceways and the rolling body of the inter-shaft bearing were considered in the model. The fourth order Runge-Kutta numerical method was used to solve the equations，and the influence of waviness excitation on the amplitude-frequency response curve and spectral characteristics of the system was analyzed. The results show that when there is waviness in the inner and outer ring raceways，the system exhibits a combination frequency of the inner and outer rotor rotation speed frequency as well as cage rotation speed frequency. And when there is waviness in the rolling body，the system has an even times of the rolling body self-rotation speed frequency. When the rotor is unbalanced，the outer ring raceway waviness will amplify vibrations in the resonance region of the outer rotor main excitation. The vibration of the system will increase in the whole speed range with the increase of the waviness amplitude，while the vibration responses of the inner ring raceway waviness and the unbalanced excitation will appear similar to the same frequency and reverse phase phenomenon in the second resonance region of the inner rotor main excitation. The vibration of the system will decrease with the increase of waviness amplitude，while the vibration in other regions will increase. Compared with the high rotating speed region，the waviness of the rolling body significantly impacts on the vibration characteristics in the low rotating speed region.

In this paper，the effect of top drive control on stick-slip and bit-bounce was studied numerically based on a three-degree-of-freedom lumped parameter model considering coupling between axial and torsional vibrations of drill strings. The simulation results indicate that although the tuned k-c control can inhibit the stick-slip and bit-bounce the drill string vibration system to a certain extent，the suppression effect of stick-slip and bit-bounce in the drill string vibration system is not ideal when the input angular velocity is high and the nominal drilling pressure is low，or the input angular velocity is small and the nominal drilling pressure is large. The tuned I-k-c control can successfully eliminate the influence of input angular velocity and nominal drilling pressure changes on stick-slip and bit-bounce，so that no matter what the input angular velocity and nominal drilling pressure values are，the bit speed will remain stable around the given input angular velocity，reducing the fluctuation of WOB，TOB and axial displacement. Therefore，compared to top-drive tuned k-c control，tuned I-k-c control is more efficient in suppressing the stick-slip and bit-bounce of drill string vibration system.

In the phenomenon of brake noise，the parametric uncertainty and correlation inevitably exist in the automotive brake systems，leading to some uncertainty and correlation of the system response. To address this problem，the uncertainty and correlation analysis for the stability responses of brake systems was carried out. A multi-ellipsoidal convex model was used to depict the uncertainty and correlation of system parameters，and the stability responses of system were characterized by the unstable modal damping ratios. The Monte Carlo simulation，the first-order perturbation method and the second-order perturbation method were respectively combined with the multi-ellipsoidal convex model respectively，and three uncertainty analysis methods of system stability responses were proposed. Based on the Monte Carlo simulation and the first-order perturbation method，two correlation analysis methods of system uncertain responses were developed respectively. The combinatorial methods for establishing the ellipsoid domains of system responses were presented by combining the uncertainty analysis and correlation analysis methods. A numerical example was given to verify the effectiveness of the proposed methods. The analysis results demenstrate that the proposed methods can effectively obtain the boundary intervals，correlation coefficients and ellipsoid domains of system responses，and the methods have high computational accuracy and efficiency.

The existing shell model is accurate in the frequency band of 0~500 Hz，making it highly suitable for tire vibration analysis. However，the modal properties of the tire belt cannot be obtained separately and the freedom as well as the number of parameters required by the model increases，because the shell model couples the tire belt and sidewall. Therefore，this shell model was improved in this paper. The shell model for simulating the tire belt remained unchanged，whereas，by using the method for approximating the sidewall used in the ring model and plate model of tire，the two-dimensional shell model for simulating the tire sidewall was replaced by an elastic foundation to simplify the boundary conditions of the tire belt and reduce the number of parameters related to the tire sidewall. The solving method for the improved shell model was developed to calculate the modal frequency and the modal shape of the tire belt. The validity of both the improved shell model and its solving method was demonstrated by an experiment.

In order to improve the climbing ability of rack vehicles，the gear-rack system is added to the traditional rail vehicles. Aiming at the problem that there are many kinds of gear-rack systems in the world at present，and the diversity of gear-rack systems equipped with them leading to the dynamic characteristics difference of rack vehicles，this paper considers the impact of gear-rack meshing on the basis of analyzing the generation mechanism of gear-rack meshing excitation，the rack vehicle coupled dynamic models with two kinds of Strub system，double row teeth Abt system and Locher system are established，and experimental verification on the model are carried out； Based on the model，the gear-rack meshing behavior of rack vehicle running at different speeds on the engagement section of the ramp is analyzed，and the influence of track irregularities on the gear-rack meshing center distance error is explored； On this basis，the wheel/rail action and car body acceleration of the rack vehicle are studied，and the rack vehicle safety are analyzed as well as stabitity. The results show that there are significant differences in the dynamic characteristics of rack vehicles with different gear-rack systems，and the Locher system has the best dynamic characteristics； The gear-rack meshing behavior of coaxial Strub system and double row teeth Abt system is poor and affected by the track irregularity obviously. The maximum impact value of the gear-rack contact force is 20.3 kN，and the meshing center distance error is 3.73 cm； The safety of coaxial Strub system and double row teeth Abt system is poor，and the maximum wheel/rail vertical force of double row teeth Abt system is 51.7 kN； The car body stability of the differential shaft Strub system is the worst. The maximum car body acceleration is 0.033 m/s²，and the stability index is 1.27. The conclusions offer theoretical support for the design，safe operation，and maintenance of mountain rack railways in China.

Vortex shedding and drift are key characteristics around the bridge girders during VIVs，and therefore it is necessary to reveal VIVs mechanisms of bridge girders from the perspective of vortex dynamics. A simplified vortex model was constructed from the perspective of aerodynamic work. Taking a typical streamlined-closed box girder as an example，a simplified wortex model was constructed from the perspective of aerodynamic work. Combined with the aerodynamic time-frequency characteristics of the bridge girder from wind tunnel experiments and the flow field characteristics around the girder based on numerical simulation method，the above model was verified and then the multi-order VIVs lock-in range mechanisms of the girder were revealed. The results indicate that the Strouhal number of the separation vortex characterizes energy effects of the vortex aerodynamics，which can be expressed as a positive integer multiple of the ratio of vortex-drift velocity to oncoming flow velocity，implying that a separation point can excite multiple VIVs lock-in ranges. There were 3 order lock-in ranges of vertical VIVs for the girder. Both the 2nd and 3rd lock-in ranges are excited and sustained by the large-scale separated vortexes separating at the leading edge and periodic drift in the drift distance between the separation point and the trailing edge. Especially，it takes about 2 and 1 vibration cycle for the separation vortexes to traverse the drift distance in the 2nd and 3rd order VIVs lock-in ranges，respectively. Therefore，they are dominated by the 2nd and 1st order simplified-vortex modes originating from the leading edge，respectively. This study verifies the rationality of the simplified-vortex model to deduce the vortices evolutionary characteristics around the bridge girder and provides a new methodology for VIVs mechanism of the bridge girders.

In order to explore the mechanical properties of high-damping thick-layer rubber bearings，this paper studies the force characteristics of horizontal shear and vertical compression of high-damping thick-layer rubber bearings under vertical compressive stress. A model considering horizontal shear deformation is established，and a vertical stiffness correction theory is proposed based on compressive stress changes. To verify the accuracy of the theoretical model，three types of high-damping thick-layer rubber bearings with different first shape coefficients were designed for horizontal quasi-static shear and vertical compression tests. The results show that the equivalent horizontal stiffness and equivalent damping ratio of the high-damping thick-layer rubber bearing are changed by the restraint effect of the internal steel plate. As the vertical compressive stress increases，the horizontal equivalent stiffness gradually decreases. In the vertical compression test，as the vertical pressure increases，the vertical compressive stiffness presents nonlinear strengthening characteristics. Through the comparative analysis of theoretical and experimental results，it can be seen that the mechanical model of horizontal shear deformation constructed in this paper can better describe the mechanical properties of high-damping thick-layer rubber bearing in horizontal shear，and the vertical stiffness correction theory can accurately calculate its vertical stiffness. The deviations from the test results under different working conditions are all within 5%.

In order to reduce the tube area proportion of the traditional frame-core tube （FCT） structure system and improve the structural economy，a high-rise structural system of the frame-distributed tubes-core tube （FDCT） is designed. The distributed tubes and rocking system are combined to form the frame-distributed rocking tubes-core tube （FDRCT） structural system，which can control the deformation mode of the structure. To reduce the adverse effects of higher modes on high-rise structures，the frame-distributed bi-rocking tubes-core tube （FDBRCT） structural system with tuned damping performance is further proposed. The dynamic models and equations of the structure are established，and the stationary random vibration analysis is carried out，which preliminarily proves that the FDBRCT structure can reduce the dynamic response of the structure more effectively. By comparing and analyzing the structural time-history analysis results of the FCT，FDCT，FDRCT and FDBRCT，the seismic capacity of the FDCT structure decreases is due to the stiffness weakening. The FDRCT structure improves the uniform degree of structural deformation，and the upper floors acceleration decreases，but the roof displacement increases. Compared with the FDRCT structure，the maximum of inter-story drift ratio of the FDBRCT structure increases significantly and the structural deformation is more uniform. Besides，the roof displacement response and internal force demand decrease appropriately. The distributed bi-rocking tubes with tuned damping brings on better seismic capacity and damping performance of the FDBRCT structure，which can improve the economy at the same time.

The durability issue of multi-age masonry structures subjected to acid rain has become increasingly prominent，but a complete time-varying model of structural durability has not been formed at home and abroad. To study the relationship between the evolution of material properties and masonry properties，accelerated corrosion tests were carried out on mortar with different mix ratios，bricks，and masonry，and a compressive strength model of masonry components considering the number of acid rain erosion cycles was established. Based on the sample data of masonry in natural environment，the mathematical relationship between the degradation degree of mechanical properties of in-service masonry structures and their service life under the action of acid rain erosion was established. The typical structure method was used to analyze the seismic fragility of a two-story constrained masonry structure，and the influence of different parameters on the fragility curve and failure probability of constrained masonry structures under acid rain erosion was discussed. The results show that the probability of severe damage and collapse of restrained masonry structures under the action of acid rain erosion increases gradually with the increase of service life under the condition that other factors remain unchanged and the intensity of local vibration is higher.