2022, 20(6):1-9. DOI: 10.6052/1672-6553-2021-068
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.
2022, 20(6):10-23. DOI: 10.6052/1672-6553-2021-051
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 highspeed plough is an important ploughing machine to achieve efficient deep ploughing，but the domestic highspeed plough basic design theory lacks integrity，systematization and standardization，This is one of the key factors leading to a gap between the highspeed adaptability of domestic highspeed ploughs and imported highspeed ploughs. Highspeed ploughs are agricultural implements with an operating speed of over 7km/h. This paper takes the curved surface of highspeed ploughs as the object of study，and focuses on the design method of the curved surface of highspeed ploughs and the influence of structural parameters on their inherent characteristics. Firstly，based on the horizontal straight element line method，the design method of highspeed plough body surface is proposed，and the design of highspeed plough body surface is standardised，forming a relatively complete and standardised design method of highspeed plough body surface. Secondly，the modal analysis of the specific highspeed plough body surface is carried out using finite element software to obtain the natural frequencies and mode shapes of the highspeed 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 highspeed 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.
2022, 20(6):24-32. DOI: 10.6052/1672-6553-2021-050
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 higherorder 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.
2022, 20(6):33-40. DOI: 10.6052/1672-6553-2021-053
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, selfexcited vibration and levitation sucking, are simulated and reproduced. The bifurcation characteristics of levitation vibration of vehicleturnout coupling system with different levitation control parameters are calculated by using the bruteforce 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 lowfrequency selfexcited vibration of the vehicle suspension system. As kp is greater than the upper limit is the coupled selfexcited 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 selfexcited vibration of turnout can be avoided.
2022, 20(6):41-48. DOI: 10.6052/1672-6553-2021-054
Abstract:In order to study the yaw instability of FPSO in regular waves, nonlinear fully coupled 6DOF 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.
2022, 20(6):49-57. DOI: 10.6052/1672-6553-2021-055
Abstract:The precision measurement and control instruments of the testbed 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 doublelayer vibration isolation device as the research object, a multimount and multidimensional 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 doublelayer 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.
2022, 20(6):58-63. DOI: 10.6052/1672-6553-2021-056
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 fluidstructure 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．
2022, 20(6):64-75. DOI: 10.6052/1672-6553-2022-042
Abstract:To solve the problems of low positioning accuracy and dependence on highprecision IMU of the existing UWBIMU positioning system for wheeled mobile robots, a localization algorithm using error state Kalman filter to integrate UWBIMUOdometer is proposed to improve the position and attitude estimation accuracy of mobile robots using linear velocity measurement of odometry and pseudomeasurement implied by the nonholonomic constraints. Meanwhile, for the nonlinear system composed of the multisensor 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 6DOF poses of the mobile robot and significantly improve the positioning accuracy compared with the conventional methods.
2022, 20(6):76-84. DOI: 10.6052/1672-6553-2021-081
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 rigidflexible 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 realtime 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 microvibration suppression scheme of the Stewart platform. The research in this paper provides effective technical support for microvibration damping and highprecision pointing of spacecraft with Stewart platform.
2022, 20(6):85-93. DOI: 10.6052/1672-6553-2022-006
Abstract:In order to meet the requirements of different flight missions, the flexible wings of the foldingwing aircrafts can be folded or deployed during the flight. As one of the key aspects of foldingwing 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.
2022, 20(6):94-100. DOI: 10.6052/1672-6553-2022-002
Abstract:The measurement acceleration of the forcebalance accelerometer (FBA) is calculated by the control force when the feedback control force is balanced with the external inertia force. Thus, the forcebalance control algorithm is the core of a forcebalance 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 forcebalance accelerometer. In this paper, taking a MEMS forcebalance sensor as the object, an optimal control algorithm of forcebalance accelerometer is proposed for minimizing the measurement error. By introducing measurement error as a new state variable, the difficult forcebalance 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 realtime highprecision 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 forcebalance accelerometer with highprecision and wide frequency band.
2022, 20(6):101-105. DOI: 10.6052/1672-6553-2022-047
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 multisymplectic method for the infinitedimensional system, a structurepreserving numerical scheme for the dynamic model is developed. In the numerical simulation, the critical step length satisfying the generalized multisymplectic 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 structurepreserving method respectively. From the numerical results, it can be found that the first six frequencies obtained by using the structurepreserving 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.
2022, 20(6):106-113. DOI: 10.6052/1672-6553-2022-012
Abstract:Herglotz’s variational principle provides a variational description of nonconservative 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 nonconservative systems with variable mass are given to illustrate the application of the results.
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