The rod string is a thin rod string composed of a coupling and a rod connected by threads. The research on the dynamic behavior of the sucker rod string is the basis to prevent the failure of the sucker rod string and reduce the operation cost of the oil well. In view of the coupling vibration of rod string，it is proposed that the torsional torque generated by the friction force between the rod and tubing is the excitation of torsional vibration. Considering the influence of friction force on the coupling vibration of rod string，a simulation model of the coupling vibration of rod string in one directional well with initial bending is established under the conditions of displacement excitation at the top，load excitation at the bottom，trajectory excitation at the curved hole and tubing constraint. The four-order Runge-Kutta method is used to solve the simulation model and to simulate the dynamic behavior of the rod string. The simulation results show that： both longitudinal and transverse vibration simulation results are affected by the coupling vibration of the rod string. The effect on longitudinal vibration is not obvious. The contact force between the rod and the tubing in the inclined section of the oil well is high，and the collision in the compressed section of the rod string is serious. Hence，the inclined section of the oil well and the compressed section of the rod string are dangerous points for eccentric wear. Under normal preload conditions，the torsional vibration of the rod string is not sufficient to cause the rod string to trip. However，when the preload force of the coupling drops below the maximum torque of the rod string，torsional vibration may cause the rod string to trip. The research provides a theoretical basis for analyzing the failure mechanism of pumping rods，improving the working life of pumping rods and optimizing the design of pumping rods.

Inerter element is a mechanical element whose inertia force is proportional to the relative acceleration between its terminals. This kind of specific inertia force is not involved in classical theory of Structural Dynamics. From the point of view of inertial and non-inertial reference frame，the inerter element is proposed as a real inertial force element. The difference between the real inertial force of inerter element and the virtual inertial force of classical mass element is also explained. In order to illustrate the differences between inerter-based technology and classical structure control technologies，the vibration mitigation mechanisms of classical technologies are elaborated firstly. Based on the mechanical relationship of inerter element and inerter system，the concepts of inerter element，inerter system and structure with inerter system are defined and explained. From the point of motion equations and energy equations of structures with inerter systems，the enhancement mechanism of inerter-based technology is revealed. The characteristics of inerter-based technology，involving dynamic negative stiffness，lightweight tuning and targeted modal control，are also described，which provides an alternative way for high-performance control of structure. On this basis，the theoretical design framework of inter-story，lightweight-tuned and isolated structures with inerter systems are given，performance-oriented optimal design namely，which can provide reference for the practical design of structure with inerter system.

Vehicle transport is an important part of logistics transport. It is of great significance to study the response of cargoes in the process of vehicle transport. Considering the coupling effect between cargo and vehicle bottom，an 11-degree-of-freedom vehicle-cargo coupling model is established. The relationship between three-way response is compared，and the influence of different road levels and cargo-related parameters （load，stiffness，damping） on the system response is taken into consideration. The results show that the coupling effect of vehicle-cargo significantly affects the system response. The influence of rotation in transportation cannot be ignored. The vibration response of cargo increases with a decrease of load，stiffness and damping. The worse the road condition is，the bigger the vibration response of cargo and vehicle bottom will be. The research results are of great significance and value for the design of vehicle-cargo transportation system.

In order to finely and continuously adjust the damping of a spring-suspended sectional model （SSSM） system in the wind tunnel test，a double-sided permanent magnet plate-type eddy current damper （ECD） device is developed in this paper. First，the basic structure of the ECD is introduced and its design points are analyzed. Then，the rationality of the structure for the ECD is analyzed by using the electromagnetic finite element steady-state analysis method，its working range is predicted，and the influence of the motion speed and position offset of the conductor plate on its working performance is analyzed. Finally，the relationship between the vertical and torsional additional damping ratio provided by the ECD to the SSSM system is derived，and the linear characteristics of the eddy current damping and the cooperative adjustment ability of the damper to the vertical and torsional additional damping of the SSSM system are verified by experiments. The study shows that the double-sided permanent magnet plate-type ECD can provide continuously adjustable linear viscous damping for the SSSM system with different scaling ratios，and the damping coefficient is stable and not easily affected by the front-back，left-right and up-down position offsets of the model，which is also suitable for the wind tunnel test of the SSSM system with large bending-torsional coupling vibration. By installing two dampers symmetrically along the diagonal of the SSSM system，the vertical and torsional damping ratios of the SSSM system can be cooperatively adjusted，which provides conditions for the fine study of the bending-torsional coupling wind-induced vibration of the SSSM system.

Brake disc bolts are important to ensure the braking reliability and the operation safety of electric multiple units （EMU）. Based on the load test technique of braking disc bolts， an experiment was conducted on the wheel-mounted braking disc bolts of the Chinese high-speed train to obtain the data of the dynamic loads，including the tensile load，the radial bending moment and the circumferential bending moment. By establishing a finite element model of the wheel-mounted braking disc bolts with the wheel-rail contact，the bolt loads under high-speed rotation are simulated and compared with test results. According to the test results and the simulation results，it indicates that the braking disc bolt loads are closely related to the operating speed of EMU. The higher the operating speed is，the bigger the variation of the bolt load will be. The loads of the braking disc bolt change periodically with the wheel rotation. When the wheel rotates once，the bolt load changes once. Meanwhile，there are some small waves on each load signal，which is caused by the wheel-rail excitation. With an increase of the operation speed，the vibration of wheel increases，and the bolt load fluctuation also increases. The results of the finite element model show that the values and directions of the radial bending moments at different positions are inconsistent. Due to the asymmetry of the wheel structure，the radial bending moment at the left cross section of the bolt is bigger than that of the right cross section.

A rate gyro adaptive weighting method is proposed for the problem that the serious coupling of elastic vibration signals and rigid-body signals in the feedback control loop of flexible launch vehicles will significantly reduce the stability of the attitude control system. The method can be applied to the cases where there are deviations in the shape slope and frequency of elastic vibration. The rate gyro observation signal is converted into a frequency domain expression，and the interpolated discrete Fourier transform method is used to identify the elastic frequency. An adaptive updating algorithm for the rate gyro weighting coefficient matrix is derived based on the frequency domain，which eliminates the elastic vibration signals of each order in a stepwise manner. A simulation calibration is carried out under different cases of deviation. Simulation results indicate that the rate gyro adaptive weighting method can realize significant suppression of elastic vibration signals in the rate gyro measurement signals and reduce the adverse effect of elastic vibration signals on the stability of the attitude control system from the source. Thus the performance of the launch vehicle attitude controller is improved and the difficulty in the controller design is reduced.

Jointed structures are widely used in engineering applications，and local nonlinear characteristics at the connection interface have an important influence on their dynamic modeling and characteristic prediction. Aiming at the problem that local connection parameters of nonlinear structural systems are unknown or difficult to measure，this paper proposes an identification method of local linear connection stiffness based on the FRF transformation from the perspective of inverse dynamic problems. By further combining with the time-domain nonlinear subspace identification method，the local linear and nonlinear connection stiffness of nonlinear structural systems can be finally obtained. The numerical example and experimental setup of the three degrees-of-freedom structural system are designed and further built to validate the proposed method. The results demonstrate that the proposed method can separate and identify the underlying linear FRF and nonlinear parameters of the nonlinear structural system，and subsequently realize the joint identification of the local linear and nonlinear connection stiffness.

In order to suppress the nonlinear vibration during the motion of a flexible manipulator，a model-free hybrid control strategy of trajectory tracking and vibration suppression based on a novel online observation of disturb forces is proposed. The Lagrange equation and singular perturbation method are employed to model and decouple the dynamics of the manipulator，which are decomposed into a slow subsystem representing rigid motion and a fast subsystem representing flexible vibration. Considering the complexity of modeling and uncertainty of model parameters，PD control method is adopted to realize trajectory tracking，and model-free adaptive control algorithm is proposed to realize nonlinear vibration control of flexible links. To solve the control divergence problem caused by unknown external disturb forces，a modified extended state observer is proposed to online estimate and real-time compensate the disturb force，which can improve the convergence performance of model-free vibration control algorithm effectively. The simulation results show that the proposed method can effectively suppress the vibration of the flexible manipulator in the presence of disturb force，and has good dynamic performance and robustness.

This paper considers a quadrotor transportation system with a four-cable-suspended payload. The relative position between quadrotor and payload is introduced and used to derive the tension of cables and describe the transportation system. A cost function inspired by payload and time is built to equipoise rapid UAV positioning and payload swing elimination. Then，the pseudo-spectral method is applied to transform the optimal control problem into a nonlinear programming problem and solve the optimal trajectory. A quadrotor transportation system’s trajectory tracking is facilitated by a PID controller. The optimal trajectory is validated through the presentation of both simulation and experimental results at last.

This paper investigates the dynamics and control problems of the long-term deorbiting of an electrodynamic tethered satellite system. The dynamics modeling of the system is carried out based on a dumbbell model assumption. To improve the accuracy of the system model，the orbital dynamics is described using a set of modified equinoctial elements，involving the effects of Lorentz force，atmospheric drag and J₂ perturbation force. Three current control strategies are proposed to regulate the electrodynamic forces for achieving a stable long-term deorbiting process，namely，the constant current input，the directionally variable current input，and the optimal control strategies. In the design of the optimal control strategy，the long-term deorbiting problem is formulated as an inverse problem of dynamics with nonlinear constraints，which is further solved via a nonlinear programming method to obtain the optimal reference trajectories. The deorbiting of the system is then achieved using the modified current control input obtained from a tracking feedback control law. Additionally，an energy-based current switch control strategy is adopted to ensure the stability of system and the efficient utilization of Lorentz force. Case studies of the system with designed physical parameters are conducted to analyze the deorbiting efficiency and to validate the effectiveness of the proposed control strategies.