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.

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.

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.

Due to the lack of research on the dynamical response of the inerter system based on non-stationary seismic excitation，an analytical solution for the time-varying variance of the dynamical response of a multi-degree-of-freedom energy-consuming structure with series-parallel layout Ⅰ inerter system （SPIS-Ⅰ） is proposed. According to the constitutive relationship of the SPIS-Ⅰ，the dynamic equations of the energy dissipation structure，and the impulsive non-stationary seismic excitation，we decouple the inertial energy dissipation structure into first-order systems using complex modal analysis and the virtual excitation method. It is convenient to obtain the unified solution of the structural response quantities such as displacement，velocity，inter-story shear force，etc. The quadratic decomposition method is used to transform the time-varying power spectral density function of the unified solution into a linear combination of the complex modal eigenvalues of the inertial-capacitated energy-consuming structure，the modal coefficients，the time-varying modal strength coefficients，and the quadratic product containing the squared term of the circular frequency. On this basis，an analytical solution for the time-varying variance of the response of the energy-consuming structure under non-stationary seismic excitation is derived by utilizing the characteristics that the non-stationary modes spectral moments have an analytical solution in the infinite integration interval. The accuracy of the proposed dynamic response power spectrum and time-varying variance is verified by using the sudden white noise excitation to analyze the dynamic response of the structure. At the same time，the dynamic response of the frame structure based on the sudden Kanai-Tajimi model is studied，and the influence of the parameters of the inertial system on the damping effect is analyzed. The proposed method can be applied to analyze the seismic response of linear structures under other non-stationary modulation functions.

In this paper，the timing transmission gear of a certain type of domestic marine 20V diesel engine is taken as the research object. Aiming at solving the problem of frequent broken teeth fault，considering the influence of various types of internal and external comprehensive excitation，the lumped parametric bending-torsion coupling dynamic model of multi-branch gear transmission shaft system of diesel engine is established. Based on Newmark step-by-step integration method，the forced vibration response is predicted，and the accuracy of the model is verified by the actual test data. Considering the influence of dynamic load，the traditional tooth root bending stress load spectrum is modified，and the strength fatigue check of the faulty gear is carried out. The results show that the peak value of the response energy at the driven timing gear of the fuel supply cam end of the diesel engine is 5.2 times that of the peak value of the response energy at the flywheel end，which indicates that the speed fluctuation at the driven gear of the timing gear is too large and the torsional vibration characteristics are poor. At this time，the bending fatigue safety factor of the tooth root is only 1.35，which is in the general reliability range and is prone to tooth breakage. Based on the engineering practice experience，the vibration optimization design scheme of the fault gear transmission system is proposed to improve the bending fatigue safety factor of the fault gear by 1.61 to ensure the safe and stable operation of the shafting. The research results reveal the mechanism of timing gear tooth breaking fault from the perspective of dynamics，provide some theoretical guidance for accurate prediction of tooth root bending stress and performance optimization，and provide theoretical support for vibration response analysis and vibration and noise reduction of diesel engine timing gear shaft system.

The fatigue failure of the structure under vibration conditions has brought hidden dangers to its own service life and the personal safety of the user. At present，there are solutions for the structural vibration fatigue such as adding reinforcement bars and laying a large amount of damping materials，but the efficiency is often low and the additional mass is excessive. In order to solve the above problems，an additional acoustic black hole （ABH） is installed on the structure to reduce the stress amplitude and extend the service life by reducing the structural response. Using a cantilever plate as the reference structure，the steady state dynamics analysis is carried out by the finite element method. The results show that the stress response at the gap of cantilever plate is significantly reduced after the addition of rectangular acoustic black hole （RABH）. Through stress and fatigue experiments，it is verified that additional RABH can reduce the stress response at the dangerous point of the structure and extend the vibration fatigue life of cantilever plate structure.

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.

The dynamic method for identifying axial force is grounded in vibration theory，making the vibration equation of a bar member crucial for accurate axial force estimation. Traditionally，the Timoshenko beam is derived from the equilibrium of transverse forces and moments. In this paper，an energy-based approach is applied to derive a new vibration equation for the Timoshenko beam under axial loading. The Ressiner energy equation for a Timoshenko beam，incorporating displacement，stress and axial force，is established using a condensation hypothesis from an energy perspective. The motion equation and stress equilibrium are calculated using the extremum principle，leading to a new free vibration equation for the Timoshenko beam under axial force. Compared to classical textbooks，the proposed dynamics equation includes two additional terms related to axial forces and shear effects. The new equation is validated through numerical simulations and laboratory experiments to identify the axial force in bar members. The results demonstrate that the proposed equation significantly improves the accuracy of axial force identification，confirming its correctness and applicability.

Aircraft often operate in complex and variable dynamic load environment，and dynamic load localization is the primary problem that needs to be solved in this field. This paper focuses on the dynamic load localization requirements of common and prone to abnormal vibrations in aircraft structures. Combining deep neural network，a rapid dynamic load localization method for aircraft structures is developed. By using Long Short-Term Memory （LSTM） neural network，the inverse implicit function model which can accurately describe the corresponding relationship between the dynamic load location and vibration response of the structure is constructed. A dynamic load localization method based on the LSTM neural network classification model is proposed. A simplified finite element model of the entire aircraft structure is established to simulate several typical dynamic load conditions that the aircraft may encounter during actual flight. The noise resistance and robustness of the established deep neural network are also studied. The simulation results show that the proposed method can accurately identify the location of dynamic loads under various load conditions，and can still maintain high locating accuracy under the measurement noise level of 10 dB and the parameter perturbation of 2.8%.

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.