Dynamic Characteristics Of Model Research Articles

Theoretical modeling and numerical simulation of dynamic contact characteristics of a spherical pump with variable friction coefficient

In this paper, the dynamic contact characteristics between a piston system and a cylinder block in a spherical pump are studied theoretically and numerically. The theoretical contact model between a piston and a cylinder is established based on its structural and operational properties, to obtain the maximum contact force quantitatively. The effects of different structural parameters and working pressures on the contact force are analyzed and discussed. The relationship between friction coefficient and rotation speed is presented. The contact pairs are modeled numerically using the finite-element method and augmented Lagrange algorithm to obtain both the tangential and normal contact characteristics. Both static and dynamic contact characteristics of the piston are analyzed and discussed. These proposed studies can provide practical suggestions on improving the wear resistance performance and durability of the spherical pump.

Modeling and Parameter Optimization of Dynamic Characteristic Variables of Ballast Bed during Operation for Dynamic Track Stabilizer

The high traffic density of railway line causes ballasted track to be extremely busy, and thus it is particularly important to improve the efficiency during railway maintenance. The changing law of dynamic characteristics of ballast bed during operation for the dynamic track stabilizer is conducive to optimize simulation analysis of the vehicle-track system, so as to provide an optimized choice of operating parameters for promoting the pertinence and efficiency of dynamic track stabilizer. This paper presents the acceleration response of vehicle-track-subgrade system during operation of a WD-320 dynamic track stabilizer and proposes the range of effective operating parameters. Then, the influence of operating parameters on the dynamic characteristics of the ballast bed is discussed for searching the optimal operating parameters under the single factor influence. Finally, the change laws including the support stiffness, damping, lateral resistance, and subsidence for the ballast bed are studied, and a parameterized model for dynamic characteristics of the ballast bed which can optimize the selection for operating parameters is constructed, rendering an effective reference variable for improving the simulation accuracy of the vehicle-track coupling system.

Dynamic Analysis and Experimental Research on the Cantilever High Speed Rotor of Turbofan Engine

Taking a simulated low-pressure rotor of a turbofan engine as the research object, the dynamic characteristic calculation model of the simulated low-pressure rotor with hollow shaft and solid shaft was established respectively by using the finite element method. The first three order critical speeds and mode shapes of the rotor were calculated systematically. The dynamic balance test of the simulated low-pressure rotor and the research on the damping effect of the squeeze film damper were carried out on the high-speed rotating test rig, and the dynamic characteristic test was completed in the full speed range. The results show that the finite element results agree well with the experimental results. The rationality of the rotor’s hollow shaft structure and rotor dynamic design was verified. The research provides reference and technical support for structural design, dynamic design and experimental research of real low-pressure rotor in engine.

Development of a mathematical model of dynamic characteristics of a drive with a planetary mechanism

The article is devoted to the development of a mathematical model of dynamic characteristics of a drive with a planetary gear mechanism. The subject of research is a drive with a planetary gear mechanism. The following issues were considered in the article: the synthesis of a planetary gear mechanism; the development of a mathematical model that describes the dynamic characteristics of the system; the determination of the dynamic characteristics of a drive with a planetary gear mechanism. Research is based on the method of determining the number of gear teeth; the method of determining the kinetic energy of the James gearbox; the method of determining the dynamic characteristics of an electric motor. The possible number of satellites is given in the article; the pitch radii of the wheels for a given modulus are defined; the moment of inertia of the mechanism reduced to the movable central wheel is determined; a mathematical model of the motion of a drive with a planetary gear mechanism is developed. Equations of motion of a drive with a planetary gear mechanism were obtained. Assuming, in a particular case, all the links of the drive with the planetary gear mechanism as rigid links, a mathematical model was developed for this system, considering the dynamic characteristics of an electric motor. A mathematical model was developed that describes the dynamic characteristics of the system. Analytical solutions for the developed mathematical model are given.

System Dynamic Approach to Improve Emergency Response in Humanitarian Logistics in Indonesia

Volatile and vulnerable conditions during disaster relief cause many problems on the coordination of aid replenishments. Research states that partnership improves coordination thus reducing the uncertainty condition along supply chain including in replenishment. This paper aims to fulfill the research gap on examining the impact of partnership in the disaster relief process. Dynamic characteristics model of this case was built by modifying the beer distribution game through Vensim PLE Plus. Model had been validated and verified with the West Java Regional Disaster Management Authority (BPPD). The simulation was run for for two types of product: repetitive demand (food package) and one-time demand (blanket). Total cost, bullwhip effect, and total distribution time for each scenario are then compared. The simulation results show that the proposed scenario, which is developed based on the usage of blockchain on the partnership system, can reduce the total distribution time for about 43% for blanket and 27% for food package. Meanwhile, the total cost for blankets can be reduced for about 29% and 13% for food packages. But on the other side, the partnership system had aggravated the bullwhip effect. Some future potential researches are also proposed in this study.

Modeling and analysis of dynamic characteristics of multi-stable waterbomb origami base

Origami has recently received wide attention, and the study on its dynamic characteristics remains a nascent field. The waterbomb origami is a common subtype of origami, and its base structure is treated as a bi-stable configuration in the literature. The systematical framework for modeling, simulation and dynamic analysis of the vibration for the waterbomb origami base is established in this paper. In the presented model, the motion of the waterbomb origami base is divided into two working patterns according to its geometric characteristic. The nonlinear governing equation of motion of the waterbomb origami base is formulated based on the Lagrange’s equation. The base’s free and forced responses can be calculated by using the fourth-order Runge–Kutta method. The developed model is validated by the results predicted by the simulation in ADAMS. With the developed theoretical framework, the base’s vertical effective stiffness and natural frequency of its linearized system are discussed to reveal their programmability with respect to the base’s structure and design parameters. Remarkably, the bifurcations of its equilibria, including the pitchfork, transcritical and (special) saddle-node bifurcations, are analyzed. Unlike the bi-stable configuration reported in the literature, the mono- and tri-stable configurations can also be realized by the base due to gravity. Furthermore, the complex nonlinear dynamic behaviors, including chaos, are revealed.

Vibration-induced dynamic characteristics modeling of electrical contact resistance for connectors

The electrical contact resistance (ECR) of connectors fluctuates periodically under vibration stress. However, a theoretical model used to explain the dynamic characteristics of ECR has not been fully proposed. The dynamic characteristics of ECR are presented after an analysis of the measured results. Moreover, according to the Greenwood-Williamson model for elastic contact and the equivalent spring model for random rough surfaces, the change in the contact pressure of electrical connectors during vibration is studied. On this basis, combining with the Holm electrical contact theory, a dynamic model of ECR under vibration conditions is established. The model can theoretically explain the phenomena of ECR found in the experiments. A good correlation between experimental and predicted ECR fluctuation is achieved.

Performance of Long Short-Term Memory Networks for Modeling the Response of Plant Growth to Nutrient Solution Temperature in Hydroponic

This study examines the development of an approach for modeling the response of plant growth to nutrient solution temperature in hydroponic cultivation in a dynamic system. Nutrient solution temperature is one of the essential manipulating factors for plant growth in hydroponic cultivation. Determining the optimal control strategy of nutrient solution temperature during cultivation could lead to maximize the growth of the plant. By identifying the process using a dynamic system, the optimal control strategy can be determined. However, developing a dynamic model of plant growth to nutrient solution temperature is not easy due to physiological behavior between them are quite complex and uncertain. We propose the long short-term memory (LSTM) networks to identify and develop a model of dynamic characteristics of plant growth as affected by the nutrient solution temperature. Chili pepper plants were used to obtain time-series data of plant growth, with five different types of dynamic nutrient solution temperature patterns for system identification. The results showed that the proposed LSTM model provides promising performance in predicting the response of plant growth to nutrient solution temperature in hydroponic cultivation.

Quality loss prediction of mechanical system life considering linear degeneration and random error

AbstractTo accurately predict quality loss of high reliability and long‐life product in service, a dynamic quality characteristics model is established based on linear degeneration and random error. According to this model, the expectation and variance of dynamic quality characteristics can be figured out. Moreover, assuming that the quality characteristics follow the normal distribution at the initial stage, the expectation of quality loss and the life distribution of dynamic quality characteristics follow three types are derived, such as L‐type (Larger is better), S‐type (Smaller is better), and N‐type (Nominal is better). According to the discount theory of quality loss, the present value model of dynamic quality loss based on the life is derived by combining life and the present value of dynamic quality loss. Then, this model is used to evaluate the quality loss of a GaAs laser and the rationality of the model is analyzed.

Dynamic characteristics and energy consumption modelling of machine tools based on bond graph theory

Fossil fuel depletion, air pollution, and climate change are imposing great pressure on industrial sectors, especially for manufacturing sectors. Energy consumption modelling is an important measure to promote the energy efficiency in manufacturing, which offers the fundamental basis for energy efficiency-related optimization. Although dynamic characteristics have a significant effect on operation of machine tools, traditional energy consumption models hardly take dynamic characteristics into consideration. This paper takes the feed system as an example and proposes a dynamic energy consumption model of machine tools with bond graph theory. Based on the structure of feed system, the proposed model is firstly expressed to a physical model and the bond graph model are established according to the law of energy conservation. Subsequently, with the augmented bond graph model, mathematical models of dynamic characteristics and energy consumption are proposed with state variables. Finally, the simulation and analysis of the proposed model are given. Results show that the proposed dynamic characteristics model and energy consumption model based on bond graph theory are reasonable and effective. Additionally, the proposed model can be used to explore the correlation between energy-consuming components and energy consumption of machine tools for realizing the high energy efficiency design of machine tools.

Modeling and experimental study of dynamic characteristics of the moment wheel assembly based on structural coupling

The microvibration of the satellite moment wheel assembly (MWA) is an essential input for integrated simulation analysis of spacecraft microvibration, which forms the basis for spacecraft vibration suppression. Therefore, it is important to guarantee high-precision data from ground measurements of vibration sources for research into the stabilization accuracy of large space telescopes. In general, a coupled wheel-to-structure disturbance model is more representative of the real environment, and two aspects of the coupling need to be considered: coupling caused by insufficient MWA stiffness and coupling caused by the vibration source installation structure. Therefore, this paper presents the relevant work conducted on these two coupling aspects. First, this paper proposes the amplification factor coefficient, which considers structural coupling based on the classical vibration model of the MWA. The average error in this case could be within 5%. This approach could reduce the computational requirements without affecting the quality of the results. Additionally, as the mass of the MWA is greater and the disturbance output is more obvious. The structural coupling with the installation foundation is unavoidable. In this paper, the effects of installation stiffness on the disturbance measurements are analyzed based on the dynamic mass measurement method and quantitative impedance theory. Finally, based on the above theory, verification testing of the disturbance and transfer models of the MWA is performed and the test results are compared with the simulation results; it is shown that a level of accuracy within ±5% can be achieved.

Some Issues of Modeling of Dynamic and Energy Characteristics of Combined Electro-Magnetic Induction Microelectromechanical Energy Converters and their Systems

Some Issues of Modeling of Dynamic and Energy Characteristics of Combined Electro-Magnetic Induction Microelectromechanical Energy Converters and their Systems

Mathematical model for dynamic characteristics of automatic electrohydraulic drive for technological equipment

The paper is devoted to the development mathematical model of automatic rotary motion electrohydraulic drive for technological equipment and structural scheme of mathematical model for drive as object of automatic control. The hydraulic drive of rotary motion with volume regulation is considered. The drive contains regulated pump and unregulated hydraulic motor. The regulation of the working volume of the pump is carried out by the electrohydraulic amplifier. The transfer function of the regulating process of the pump working volume is represented by aperiodic link of the first order. The adequacy of mathematical model for dynamic characteristics of electrohydraulic drive has been confirmed experimentally by the Fisher criterion. To verify the adequacy, we compared the experimental and calculated transient processes for the shaft angular rotation velocity of hydraulic motor when applying the control signal. The mathematical model of automatic rotary motion electrohydraulic drive for technological equipment as object of automatic control was used as basis for further research on the synthesis of automatic control systems for equipment.

Nonlinear dynamic characteristic modeling and adaptive control of low speed maglev train

Nonlinear dynamic characteristic modeling and adaptive control of low speed maglev train

A Physics-Based Compact Static and Dynamic Characteristics Model for Al2O3/InxAl1−xN/AlN/GaN MOS-HEMTs

This paper presents a physics-based compact of indium mole fraction dependent analytical model for static and dynamic characteristics of GaN-based MOS-HEMTs. The model covers all the different operating regimes of the MOS-HEMT devices. The model is evaluated step by step with excellent agreement compared with the simulated data obtained by Atlas-TCAD simulation and the experimental data have demonstrated the validity of the proposed model for different indium mole fractions (12, 15, 17, and 18)%. From static and dynamic characteristics, it is also observed that by careful setting of the indium mole fraction for GaN-based MOS-HEMTs can improve the performance of the device, and; hence, it is proper for high performance low loss applications. MOS-HEMTs produce high drain current of 1227 A/m at a positive gate bias $$V_{\rm{gs}}$$ of 3 V and with 15% of indium mole fraction, high transconductance of 268 S/m, and high cut-off frequency of 35 GHz at x = 18% indium mole fraction.

Analysis of vibration high-frequency dynamic characteristics of wheelless rail vehicle system based on fuzzy logic control

Track irregularity is the main source of vibration excitation of vehicle-track weighing system, which has an important impact on the safety, stability and comfort of train operation, and it is also the main factor limiting the speed of train operation. Higher requirements are put forward for track smoothness with the rapid development of China’s railways. Therefore, it has a great theoretical and practical significance to study the relationship between track irregularity and random vibration of vehicle-track cooker-in system and the evaluation method of track smoothness. In this paper, a model construction method is proposed based on machine learning fuzzy logic control and neural network algorithm to analyze the high frequency dynamic characteristics of ballastless track wheel-rail vehicle system. Firstly, a numerical analysis model of high frequency dynamic characteristics of ballastless track wheel-rail vehicle system is established by using linear discrete elastic-yellow damper element connection model; Secondly, the Rough Set Block Neural Network is introduced to optimize the dynamic characteristic analysis model, and the intelligent model of model optimization analysis is established. Finally, the validity of the proposed algorithm is verified by simulation experiments of practical examples.

Dynamic Phasor Modeling of Various Multipulse Rectifiers and a VSI Fed by 18-Pulse Asymmetrical Autotransformer Rectifier Unit for Fast Transient Analysis

To study the fast modelling of dynamic characteristics caused by power electronic switching, the dynamic phasor (DP) theory based on the time-varying Fourier decomposition and frequency shifting is firstly applied to the modelling of various multipulse rectifiers. The DP model for symmetrical 12-pulse phase-shifting reactor rectifier unit (PSR-RU) is derived with model order reduction, relations between ac and dc terminals, and Taylor series expansion. The DP model of asymmetrical 18-pulse autotransformer rectifier unit (AT-RU) is proposed based on the switching functions expressed in the DP domain. Meanwhile, the DP model of voltage source inverter (VSI) fed by asymmetrical 18-pulse AT-RU is built with the harmonic state-space (HSS) equations. Under both balanced and unbalanced conditions, the good calculation accuracy and rapid simulation speed of the developed DP models are validated by the detailed time-domain (TD) simulation.

Stability Analysis of a Subsonic Aircraft with Flight Control System Including Structural Damage

This paper aims to study a modeling technique for flutter analysis of subsonic aircraft by using finite element analysis including flight control failures. By applying distribution of stiffness of dynamic characteristics model as a beam element and distribution of mass as a concentrated mass, the configuration of aircraft idealized. The aerodynamic force model includes all lifting surfaces, fuselage and utilized doublet lattice method in consideration of mutual interference effect between lifting surface and lifting face and lifting surface and fuselage, in empty fuel condition, to 1.74 Vd and in full fuel condition, to 1.71 Vd. There has been no aeroelastic instability on the subsonic aircraft. As a result of flutter analysis based on hinge damage of control surface, it has been proved that it is safe to damages. However, it is required to observe carefully whether the hinge of rudder has been damaged, since the flutter seed decreases significantly when there is one. The control system that has major impact on the aeroelastic characteristic of subsonic aircraft has been modelled to represent the rotational mode of rigid body and elasticity. The flutter analysis has been conducted on empty fuel condition, full fuel condition, changes in volume of mass balance, cases of hinge damage and its results.

Verification of a design model and evaluation of a technique of manufacturing aircraft engine composite parts on the basis of dynamic tests

The results of finite element modeling and experimental evaluation of dynamic characteristics (vibration modes and frequencies) of the composite element of aircraft power plant structures are presented. The aim of the work is to develop effective design and technological schemes for thin-walled complex-geometry composite parts, taking into account the peculiarities of mechanical behavior of polymer composite materials to the fullest extent possible. A method for determining the parameters of natural oscillations of composite parts in a free state using a ping test is developed, which allows excluding the influence of kinematic boundary conditions and obtaining frequency characteristics that depend only on the local characteristics of the material which are primarily determined by the manufacturing technology. According to the results of measurements of the amplitude-frequency parameters of the dynamic response, spectrograms of damped oscillations are obtained the peak values of which correspond to the experimental evaluation of the natural frequencies of the composite part. Verification of the design model was carried out according to the results of the ping test and a method for assessing the quality of technological processes of manufacturing thin-walled carbon fiber structures was proposed.

Complementary cooperation dynamic characteristics analysis and modeling based on multiple-input multiple-output methodology combined with nonlinear control strategy for a polymer electrolyte membrane fuel cell

This research proposes a new dynamic nonlinear model and its nonlinear control strategy for polymer electrolyte membrane fuel cell (PEMFC) by considering all possible gas pressures and water effects. In this research, in order to prolong the PEMFC stack life, the nonlinear controller based on the proposed model is properly designed by controlling gas pressures to the reference values. Specifically, our proposed dynamic PEMFC model significantly adapts the multiple-input multiple-output (MIMO) system that can directly utilize the feedback linearization for the nonlinear control. All possible water effects are considered for optimal designing of the dynamic PEMFC model. In the control design, gas pressures in the anode and cathode, the relative humidity, as well as the fuel cell voltage are defined as the control objectives to minimize the pressure difference between the anode and cathode, and control the humidity and the fuel cell voltage. Based on these control objectives and the proposed dynamic model information, the details of the proposed control design scheme in the PEMFC model were described in this research. A transient MATLAB/SIMULINK simulation and experimental results were performed and gathered to validate the proposed PEMFC model with the nonlinear controller being approximately average two times more effective in terms of the overshoot suppressing in the pressure control during the transients. According to these results, they show the superiority of the proposed dynamic PEMFC model as a good platform in order to design a nonlinear controller using the feedback linearization for having a better transient performance of the PEMFC compared to the linear controller.