Abstract:This paper attempts to summarize the traditional engineering fields and emerging engineering fields involved in the vibration problem in engineering, as well as the related research fields and research trends. However, due to the complexity of the vibration problem itself and continuous emergence of emerging engineering fields, this is a big topic, and it may be difficult to summarize accurately and in place in a small space.

Abstract:South Xinjiang is an important agricultural production base in China. Due to its unique geographical location，the soil of agricultural land is subjected to soil caking and high salinity，which seriously hinders the normal growth of crops. In order to ensure the sustainable development of agriculture，deep ploughing has become a necessary part of improving the soil environment，and the highspeed plough is an important ploughing machine to achieve efficient deep ploughing，but the domestic highspeed plough basic design theory lacks integrity，systematization and standardization，This is one of the key factors leading to a gap between the highspeed adaptability of domestic highspeed ploughs and imported highspeed ploughs. Highspeed ploughs are agricultural implements with an operating speed of over 7km/h. This paper takes the curved surface of highspeed ploughs as the object of study，and focuses on the design method of the curved surface of highspeed ploughs and the influence of structural parameters on their inherent characteristics. Firstly，based on the horizontal straight element line method，the design method of highspeed plough body surface is proposed，and the design of highspeed plough body surface is standardised，forming a relatively complete and standardised design method of highspeed plough body surface. Secondly，the modal analysis of the specific highspeed plough body surface is carried out using finite element software to obtain the natural frequencies and mode shapes of the highspeed plough body surface. Finally，the effects of changes in height deviation，guide curve opening，guide curve mounting angle and spar angle on the inherent frequency of the curved surface of the highspeed plough are investigated.The results of this paper provide a reference for the design and optimisation of high speed plough structures, and provide an appropriate complement to the basic design theory of high speed ploughs.

Abstract:The dynamic problem of the cable with hose of alongside liquid cargo replenishment of ship was analysed, in and the effects of inclination angle of the cable, the position of saddle, the span of the cable were considered. The stress state of the cable and hose at each saddle position were obtained by the principle of statics． Then the dynamic model of the cable and hose of alongside liquid cargo replenishment were simplified to the cable system with multiple lumped masses. The higherorder modal truncation of partial differential dynamic model was carried out by the Galerkin method. Moreover the dynamic characteristics of this system were analyzed under typical operating conditions. The results shows that there were complex dynamic characteristics in this system, such as typical period and chaos. The effects of the cable span and damping on the dynamic characteristics of the system were analyzed.

Abstract:Based on the bifurcation theory, the levitation stability of maglev vehicle turnout beam coupling system is studied. The magnetic levitation electromagnet model, levitation controller model, vehicle system model and turnout beam model are established, and the vehicle turnout coupling model system is constructed. The dynamic levitation behavior of maglev vehicle on turnout beam is analyzed in detail. Three levitation states,i.e., steady levitation, selfexcited vibration and levitation sucking, are simulated and reproduced. The bifurcation characteristics of levitation vibration of vehicleturnout coupling system with different levitation control parameters are calculated by using the bruteforce method. The relationship between the mass and natural frequency of turnout and the stability region of suspension control parameters is studied. The results show that there are upper and lower limits for the stability region of the control parameter kp. As kp is less than the lower limit，there is the lowfrequency selfexcited vibration of the vehicle suspension system. As kp is greater than the upper limit is the coupled selfexcited vibration of the turnout. When the natural frequency of turnout is close to suspension frequency, the upper limit value of stability region of suspension control parameters is the smallest, and the lower limit value of stability region is not affected. By changing the mass of turnout, the levitation stability region can be expanded, and the coupling selfexcited vibration of turnout can be avoided.

Abstract:In order to study the yaw instability of FPSO in regular waves, nonlinear fully coupled 6DOF motion equations of moored floating body are established and solved numerically. The accuracy of equation is verified by comparing equilibrium yaw angles calculated by numerical simulation with model test. The influence of yaw instability on motion responses is studied. The influences of initial yaw angle and wave steepness on yaw instability and motion responses are also studied. The results show that the FPSO may lose the weathervane effect at particular wavelength to ship length ratio, and this increases the wave loads acting on the hull which arouse greater responses in roll and heave. The wave steepness doesn’t affect the final equilibrium yaw angle. However, it affects the time required to reach equilibrium and the response amplitude. The initial yaw angle affects the final equilibrium position and motion response of the FPSO.

Abstract:The precision measurement and control instruments of the testbed will be disturbed by the vibration equipment in the working process, which will affect its normal operation. Therefore, it is necessary to use the vibration isolation device for vibration protection. Taking the doublelayer vibration isolation device as the research object, a multimount and multidimensional flexible dynamic model is established by combining the finite element method and impedance synthesis approach. The effects of different instrument mass, system structure and isolator parameters on the vibration transmission characteristics of the vibration isolation device are analyzed. The results show that the designed doublelayer vibration isolation device can meet the application requirements. Increasing the thickness of the upper table and reducing the stiffness of the vibration isolator can significantly improve the vibration isolation efficiency.

Abstract:With the development of high pressure and high power of aviation hydraulic system, the vibration problem of hydraulic pipeline is increasingly not to be ignored. Reducing the vibration of hydraulic pipeline is of great significance to improve the safety of aircraft during flight. In this paper, the vibration characteristics of aviation hydraulic pipeline under pump source pulse condition are studied, and the mathematical model of vibration characteristics of hydraulic pipeline under the influence of fluid pressure and flow rate is established. The actual hydraulic pipeline system is modeled and fluidstructure coupling simulation is carried out by using finite element software ANSYS, and the corresponding vibration response is obtained. The results show that the natural frequency of hydraulic pipeline varies with different fluid velocity and pressure. When the fluid pulsation frequency is close to the natural frequency of the pipeline system, the system will have resonance and the vibration amplitude increases greatly．

Abstract:To solve the problems of low positioning accuracy and dependence on highprecision IMU of the existing UWBIMU positioning system for wheeled mobile robots, a localization algorithm using error state Kalman filter to integrate UWBIMUOdometer is proposed to improve the position and attitude estimation accuracy of mobile robots using linear velocity measurement of odometry and pseudomeasurement implied by the nonholonomic constraints. Meanwhile, for the nonlinear system composed of the multisensor measurement models, a detailed theoretical analysis and mathematical proof of the observability of the system is carried out by an observability rank condition analysis method based on the Lie derivative, and the conditions under which the system is locally weakly observable are concluded, which determines the required measurement outputs and control inputs for unbiased estimation of the system states. The simulation results show that when the observability conditions are satisfied, the state estimation approach proposed in this paper can effectively obtain the accurate 6DOF poses of the mobile robot and significantly improve the positioning accuracy compared with the conventional methods.

Abstract:The modeling method of forward recursive formulation of flexible multibody systems is used in this paper. Based on the principle of velocity variation, a rigidflexible coupling dynamics model of a spacecraft with Stewart platform, flexible solar panels and CMG components was established. Due to the large degree of freedom of the model, unable to meet the needs of realtime control. Therefore, an equivalent simplified model of the Stewart platform with simplified legs was established. Through comparison with the complete model of the flexible Stewart platform spacecraft, the correctness and efficiency of the established dynamic model were verified. The influence of the motion of the main platform and the vibration of the flexible panels board on the dynamic response of the payload is analyzed. It is pointed out that the motion of the main platform cannot be simply fixed or the vibration of the flexible panels cannot be ignored when designing the microvibration suppression scheme of the Stewart platform. The research in this paper provides effective technical support for microvibration damping and highprecision pointing of spacecraft with Stewart platform.

Abstract:In order to meet the requirements of different flight missions, the flexible wings of the foldingwing aircrafts can be folded or deployed during the flight. As one of the key aspects of foldingwing aircrafts, successful deployment and locking of the folding wings matters. Hence, in this work, the passive deployment dynamics of a hypersonic folding wing is studied. An accurate dynamic model is established and the parameters for deployment is investigated for the purpose of reducing the shock vibrations of the folding wing after deployment. Firstly, a flexible multibody dynamic model of the folding wings is established via the absolute nodal coordinate formulation (ANCF), which can accurately describe the large rotations and large deformations of the folding wings. The piston theory is utilized to derive the aerodynamic forces of the folding wing during deployment. The generalized α algorithm is used to solve the system dynamic equations. Secondly, the influence of the deployment torsion bar, the retarding spring, and the flight attitude on the dynamic response of the folding wing is studied. The system parameters are optimized to effectively reduce the shock vibrations of the folding wing.

Abstract:The measurement acceleration of the forcebalance accelerometer (FBA) is calculated by the control force when the feedback control force is balanced with the external inertia force. Thus, the forcebalance control algorithm is the core of a forcebalance sensor. Most of the traditional control algorithms aim at minimizing the offset position of the sensitive elements from the equilibrium, which limits the measurement accuracy and applicable bandwidth of the forcebalance accelerometer. In this paper, taking a MEMS forcebalance sensor as the object, an optimal control algorithm of forcebalance accelerometer is proposed for minimizing the measurement error. By introducing measurement error as a new state variable, the difficult forcebalance control is transformed into an optimal control problem for response minimization, from which the analytical expression of the optimal control force is obtained. Based on the proposed control strategy, the realtime highprecision detection of unknown acceleration signal is realized. Numerical simulations are carried out for three different types of input acceleration signals (step, periodic and random). It is found that the proposed algorithm can accurately detect all kinds of input acceleration signals, and the frequency band of the measured signal reaches up to kHz. At the same time, the vibration response of the sensitive element can be effectively controlled, which guarantees the large dynamic range of a FBA. Our work provides the basis for the research of high performance forcebalance accelerometer with highprecision and wide frequency band.

Abstract:The axial velocity and the material’s heterogeneity introduce the great challenge on the vibration analysis of the functionally graded beam with an axial velocity. In this work, the dynamic model of the transverse vibration of the functionally graded beam with an axial velocity is reviewed in brief firstly. Based on the dynamic symmetry breaking theory and the generalized multisymplectic method for the infinitedimensional system, a structurepreserving numerical scheme for the dynamic model is developed. In the numerical simulation, the critical step length satisfying the generalized multisymplectic condition is obtained with the given material parameters. The first six frequencies of the transverse vibration model are presented employing the differential quadrature method, the complex modal method and the structurepreserving method respectively. From the numerical results, it can be found that the first six frequencies obtained by using the structurepreserving method are highly consistent with those obtained by using the complex modal method. To improve the precision of the differential quadrature method, the main factors resulting in the error are investigated. The main contribution of this work is proposing a new approach to analyze the complex dynamic problem like the transverse vibration of the functionally graded beam with an axial velocity considered in this paper.

Abstract:Herglotz’s variational principle provides a variational description of nonconservative dissipation problems, and variable mass mechanics is widely used in nature and engineering. Therefore, it provides a new way to study variable mass mechanics by applying Herglotz’s variational principle to Lagrange equations and conservation laws of variable mass mechanics systems. In this paper, the Herglotz type generalized variational principle of mechanical systems with variable mass is established and the Herglotz type Lagrange equations of mechanical systems with variable mass are derived. Herglotz type Noether symmetry of variable mass mechanical systems is defined, and the Herglotz Noether theorem and its inverse theorem are established and proved. At the end of this paper, two concrete examples of nonconservative systems with variable mass are given to illustrate the application of the results.