Dynamic Response Of System Research Articles

Electromechanical coupling dynamic responses of motor-gear system under different motor control methods

Electromechanical coupling dynamic responses of motor-gear system under different motor control methods

Dynamic plastic damage analysis of bending-torsion coupling in cross stiffener systems under mass impact

ABSTRACT This study proposes a simpler theoretical model to predict the bending-torsion coupling dynamic plastic response of cross stiffener systems under mass impact. Traditional methods often rely on torque balance and momentum conservation equations, which involve complex and difficult calculations. To simplify this process, the study uses the law of energy conservation and applies the variational method to solve the dynamic plastic damage of the cross stiffener system. The plastic response of a single stiffener is first analyzed and compared with existing theories, showing consistent results for maximum displacement. The study then extends the model to more complex conditions, performing comparative analyses on stiffeners of different sizes through numerical simulation. The findings show that the maximum displacement at the load and node remains within a reasonable range, with a displacement difference of only 0.9 mm and an error margin of 4.79% in one of the test conditions.

Transient Response of MDOF Nonlinear Dynamical System under Stationary Random Excitation

Transient Response of MDOF Nonlinear Dynamical System under Stationary Random Excitation

Review of PID Control in Industrial Areas for Tobacco Production, Self-driving Car Technology and Robotic Arm Robots

Abstract. PID control is widely employed across diverse industries such as tobacco production, autonomous car technology, and mechanical arm robotics. This shows that PID control has a substantial developmental potential, so I choose the PID control as the topic. Since few people summarize its different applications in different industries, this study has the motivation to comprehensively summarize the applications of PID. This research provides an in-depth overview and analysis of PID control's varied applications in tobacco production, autonomous car technology, and mechanical arm robotics. It focuses on addressing practical challenges and exploring optimization strategies encountered in these fields. This article is summarized using the methods of the review. PID plays a crucial role in enhancing stability, precision, and response speed in these applications, thereby improving overall control system dynamic response performance. This study consolidated existing literature to offer insights into PID's effectiveness across these industrial sectors, shedding light on its impact and potential for further advancements in control technology.

Shock-induced twinning/detwinning and spall failure in Cu–Ta nanolaminates at atomic scales

Abstract This study provides new insights into the role of interfaces on the deformation and failure mechanisms in shock-loaded Cu–Ta–Cu trilayer system. The thickness of the Ta layer, piston velocities, and shock pulse durations were varied to explore the impact of impedance mismatch and loading conditions on spallation behavior and twin formation. It was found that the interfaces play a crucial role in the dynamic response of these multilayered systems since secondary reflection waves generated at the interfaces significantly affected the peak stress and pressure profiles, influencing void nucleation and failure modes. In the trilayer systems, failure predominantly occurred at interfaces and within the Ta layer, with void nucleation sites and twinning behavior being markedly different compared to single-crystal Cu and Ta. Increasing the Ta layer thickness modified the wave interactions, leading to different failure locations. Higher piston velocities were associated with increased spall strength by enhancing wave interactions and void formation, particularly at the interfaces and within the Ta layer, under specific configurations. Additionally, shorter shock pulse durations facilitated earlier initiation of the release fan, reducing twin formation and altering the failure dynamics by accelerating twin annihilation and pressure release.

Dynamic Interaction Analysis of a Coupled System of Permanent Maglev Train and Flexible Track Beam

Vehicle–track beam coupling resonance greatly influences the vibration response of the suspended permanent (SPML) system. Therefore, the study established the coupled dynamic model of the SPML train and the track beam using. The model is used to analyze the dynamic response of SPML trains when passing through the long-span flexible track beam at resonance speed. The accuracy of the model was verified by field tests, which simulated and compared the dynamic responses of maglev train and track beam systems at different running speeds. Furthermore, the coupled vibration response of the train and track beam at resonant speed are investigated to gain insight into the mechanism and vibrational properties of the SPML system in a resonant background. It shows that the dominant frequency of the train, suspension frame, and track beam is 6.74[Formula: see text]Hz. They result in resonance in the SPML system at 30[Formula: see text]km/h. Further analysis shows that adjusting the vertical distance between the mass center of the vehicle and the track beam can effectively alleviate the resonance between the vehicle and the track. Additionally, deformation at the ends of the long-span track beams affects the levitation force and gap of the suspension frame, offering valuable guidance for SPML system design.

Experimental evaluation on dynamic performance of medium–low-speed maglev vehicle running on low-positioned subgrade

ABSTRACT As a novel urban rail transit system with relatively low construction costs, medium–low-speed maglev transportation is currently experiencing rapid development in China. However, there have been rare studies on the experiments of medium–low-speed maglev vehicle passing curves and low-positioned subgrade. Therefore, this paper systematically conducts on-site dynamic tests on the Qingyuan Maglev Tourism Line. The experiment provides a detailed analysis of the dynamic characteristics of the vehicle system and subgrade under varying speeds up to 132 km/h. The study explores the impacts of operating speed, track layout, and type of girder structure. The results indicate that a significant increase in operating speed and the application of emergency braking intensify the dynamic response of the vehicle system. When passing through the R700m curve and low-positioned subgrade sections at different speeds, the primary vibration frequency of the sprung structure is below 2.5 hz, while the unsprung structure shows a wide frequency distribution. The peak frequencies of the vibration for the low-positioned subgrade are mainly distributed in the 60–140 hz range, and the vibration response of the girder remains at a low level. The Sperling index values, levitation gap, and lateral offset of the levitation electromagnet of the testing vehicle do not exceed 2.5, 4 mm, and 10 mm, respectively, indicating excellent ride comfort and stable levitation performance. The results of this test study provide a reliable assessment of the safety of the vehicle and subgrade system and would help precise modelling of vehicle and subgrade system in the future.

Design of a robust intelligent controller based neural network for trajectory tracking of high-speed wheeled robots

The control design of wheeled mobile robots is often accomplished based on the robot’s kinematics which imposes critical challenges in the motion tracking control of such systems. In the related literature, most works designed dynamic controllers based on the terms of voltage or torque; however, the velocity is often utilized in industrial and commercial applications. To address this issue, this paper focuses on the design of a velocity-based control for the trajectory-tracking problem of mobile robots in practical applications including measurement acquisition. The control design of the mobile robot is realized in two separate parts using kinematic control and dynamic control. The design of kinematic control is carried out based on the robot’s kinematics where the motion is described without considering the forces and torques. A radial basis function (RBF) neural network (NN) based on the model-free controller is designed for the dynamic controller of mobile robots without relying on the system dynamics. In the proposed dynamic control, a time-delay estimation is adopted to estimate the disturbances and noises in the mobile robot and remove them from the feedback loop control. Several typical scenarios of mobile robots with high-speed movements are conducted to assess the feasibility of the proposed NN controller-based time-delay estimation under noises and disturbances. To show the supremacy of the suggested controller, the dynamic responses of the mobile robot test system are compared with the prevalent controllers. The extensive simulation and real-time examinations reveal the capability of the proposed NN controller-based time-delay estimation to control high-speed mobile robots under high-level noises and disturbances.

Reduced-Order Modeling for Dynamic System Identification with Lumped and Distributed Parameters via Receptance Coupling Using Frequency-Based Substructuring (FBS)

Paper presents an effective technique for developing reduced-order models to predict the dynamic responses of systems using the receptance coupling and frequency-based substructuring (RCFBS) method. The proposed approach is particularly suited for reconfigurable dynamic systems across various applications, like cars, robots, mechanical machineries, and aerospace structures. The methodology focuses on determining the overall system receptance matrix by coupling the receptance matrices (FRFs) of individual subsystems in a disassembled configuration. Two case studies, one with distributed parameters and the other with lumped parameters, are used to illustrate the application of this approach. The first case involves coupling three substructures with flexible components under fixed–fixed boundary conditions, while the second case examines the coupling of subsystems characterized by multiple masses, springs, and dampers, with various internal and connection degrees of freedom. The accuracy of the proposed method is validated against a numerical finite element analysis (FEA), direct methods, and a modal analysis. The results demonstrate the reliability of RCFBS in predicting dynamic responses for reconfigurable systems, offering an efficient framework for reduced-order modeling by focusing on critical points of interest without the need to account for detailed modeling with numerous degrees of freedom.

Static and dynamic characteristics of electrostatically coupled MEMS beams under asymmetric actuation conditions

Abstract Electrostatically actuated microbeams have gained prominence due to their applications as micro-actuators and ultrasensitive sensors. In this study, we investigate the dynamic behavior of electrostatically coupled microbeams, specifically focusing on the effects of asymmetric actuation conditions. Our investigation encompasses both static and dynamic characteristics of the coupled microbeam system, considering various gap ratios between the beams and the fixed electrodes. Within the coupled system, two doubly clamped microbeams are positioned between two fixed electrodes. We develop a reduced-order model (ROM) to investigate static and dynamic responses of the coupled system. To validate the ROM, we rigorously compare its results with finite element (FE) simulations. Our findings reveal that the gap ratios play a pivotal role in shaping the system’s response. Notably, first two natural frequencies are important for design of micro-resonators and they exhibit complex variation with respect to the applied DC voltage. Moreover, we explore resonance frequency tunability and investigated interplay between geometric nonlinearity and nonlinear electrostatic actuation forces. These insights contribute significantly to the efficient design of MEMS resonators.

Dynamic responses of germination characteristics and antioxidant systems to alfalfa (Medicago sativa) seed aging based on transcriptome

Seed aging poses a significant challenge to agronomic production and germplasm conservation. Reactive oxygen species (ROS) are highly involved in the aging process. However, dynamic response of germination characteristics and antioxidant system to seed aging are not yet very clear. This study explored the potential physiological mechanisms responsible for the reduced and rapid loss of seed vigor in alfalfa, and identified key genes regulating seed vigor. The germination percentage exhibited a decreased trend with the prolongation of aging duration. From 16 to 32 days of aging, the antioxidant enzyme activities of SOD, POD, CAT, DHAR and MDHAR declined significantly, which lead to the disruption of ROS balance and a significant increase in ROS levels, exacerbating seed aging. Based on transcriptome, 29 differentially expressed genes (DEGs) including SOD1, APX-2 and GST-7 within the ROS scavenging system showed a significantly down-regulated expression trend at aging of 16 and 24 days, indicating the abnormal function of antioxidant metabolism. Furthermore, some related genes including ATPF1B, ATPeF0C-3, NDUFS1, NDUFS3 and ND2 in the mitochondrial ETC exhibited a downturn following seed aging, which would result in the losing of seed vigor. This study has uncovered a significant array of potential target genes within the seed antioxidant system and mitochondrial ETC. These discoveries offer a wider lens for delving into the molecular regulatory mechanisms of seed aging. Further research is crucial to comprehensively elucidate the precise pathways through which these pivotal genes regulate seed vigor.

The wave-current combined effect on the dynamic response of monopile-supported system considering fluid-structure interactions

ABSTRACT The monopile-supported offshore wind turbines (OWTs) are subjected to complex marine environment loads, the dynamic responses of wind turbine structures under wave and current loads are critical for structural safety assessment, which involves the interaction of fluid and structure fields. This study proposed an approach for simulating the two-way (T-W) fluid-structure interaction (FSI), the dynamic responses of the wind turbine support structure under the combined action of wave and current load are investigated. Subsequently, the effect of wave-current interaction, scour depth and flow velocity on the dynamic responses of monopile-supported OWTs are analysed and some useful guidelines are provided. The results indicate that the wave-current interaction can strongly influence the dynamic responses of OWTs, especially for larger scour depth and higher flow velocity. In addition, the displacement amplitude of OWT decreases by 15% under the current load in consideration of the fluid-structure interaction and the bearing performance of the pile improves accordingly.

Integrated AGC Approach for Balancing the Thickness Dynamic Response and Shape Condition of a Hot Strip Rolling Control System

Thickness and shape are two significant indices in the tandem hot strip rolling process. Excessive thickness correction can cause rolling force imbalance, leading to deteriorated shape conditions. Aiming at this problem, we propose a new monitor automatic gauge control (M-AGC) with consideration of the rolling force distribution to not only keep the shape condition but also improve the robustness of the rolling process. First, the M-AGC with the Smith predictor control structure was studied. Second, based on the rolling force and thickness correction redistribution algorithm, shape balance automatic gauge control (SB-AGC), the phenomenon of rolling force imbalance was improved. Third, the transient response was improved by adding a command prefilter to the upstream stands, which is asynchronous shape balance automatic gauge control (ASB-AGC). The proposed algorithms can be applied to all steel grades and are easy to implement. Finally, cross-validation was conducted through numerical simulations and application results, confirming the alignment between the theoretical derivation and practical implementation. The simulation results show improvements in both the rolling force balance and the thickness response. The practical application results also confirm that better flatness conditions and thickness response can be achieved, significantly reducing the amount of head-end cutoff losses.

Non-equilibrium thermodynamics in NMR: understanding quadrupolar spin-1 systems.

In this study, we explore the non-equilibrium thermodynamics of a quantum system,
specifically focusing on spin-1 quadrupole nuclei. By employing fundamental principles
from quantum mechanics and statistical mechanics, we aim to understand the behavior
of the quadrupole spin-1 nuclei when subjected to external perturbations. Our analysis
involves the investigation of the system's dynamic response to non-equilibrium conditions through the manipulation of a work parameter. By treating work as a random
variable, we gather data from multiple cycles of finite duration, enabling us to compute
the complete distribution of the work generated during this process. Through these
finite-time non-equilibrium process data, we are able to determine equilibrium values
for important quantities such as the difference in free energy between the initial and
final states of the system. Additionally, we explore various properties of the system's
work distribution.

High-speed nonlinear dynamic analysis of dual springs system considering internal structural impact

The significant dynamic responses of helical springs are widely reported as the main reason causing pre-failure in various high-speed conditions. Though the concept of nonlinear springs is proposed to reduce their own dynamic responses, they are found to induce unexpected spike forces during operations. This study presents a dual springs system used within high-speed sports car engines, which aims to mitigate the dynamic responses and spike forces. Analytical models are first developed to calculate the fundamental frequencies of the outer and the inner springs of the system. Then, a transient finite element (FE) model is developed to accurately simulate the dual springs system working at various high engine speeds and validated experimentally by the results of the engine head tests. The simulations reveal that the use of dual springs with different natural frequencies can mitigate the dynamic responses of the whole system to a certain extent. Nevertheless, it is still a compromise as coil clash occurs on each isolated spring though the effects are reduced. The findings of this study indicate that the establishment of direct connections between every component spring would be a promising way to better mitigate the dynamic responses including the effects of coil clash.

Fixed Switching Frequency Model Predictive Control and Passivity Based Control for DC-DC Converter

The DC-DC converter represents a crucial component in the renewable energy sources. The stability and dynamic capability enhancement of the DC/DC converter have emerged as a significant research topic in the current era. Model predictive control (MPC) is particularly prevalent due to its high dynamic response speed, simplicity of the controller design, and capacity for multi-objective optimization. However, the traditional finite control set model predictive control (FCS-MPC) method is suffer to variable switching frequency and vast computing. To improve the dynamic performance of the converter, a novel nonlinear control strategy named fixed switching frequency MPC and passivity-based control (PBC), named FSFPBMPC, is proposed, which could achieve fixed switching frequency and enhance the system's dynamic response speed. Firstly, the Euler-Lagrange (EL) model of the boost converter is established. Secondly, the relationship between duty cycle and MPC is established. Ultimately, the output voltage of PBC is incorporated into the cost function of the FCS-MPC. The characteristics of PBC power shaping and damping injection can enhance the system's immunity to interference, improve the system's dynamic response speed, and thus reinforce the system's stability. Then, depending on MATLAB, the simulation results proved that the proposed strategy has the same effect as we expected.

The effect of disc deformation on the dynamic response of multi-disc systems: A tilting-impact model originating from the wet clutch

Analyzing the dynamic response of a wet multi-disc clutch is crucial for relevant fault diagnosis research. However, characterizing the tilting-impact phenomenon between the friction discs remains ambiguous. This paper presents a tilting-impact model of a multi-disc system under dry conditions and investigates the effect of disc deformation on the system dynamics. Firstly, Euler angles and Euler kinematic differential equations are introduced to describe the spatial position and orientation of the spinning-tilting disc. The aligning centrifugal moment, spline friction force, and tilting-impact forces for both flat and deformed discs are derived. A bench test is conducted to validate the model by comparing simulation and experimental signals at various rotation speeds. The results indicate that the occurrence of tilting-impact phenomena in dry conditions requires external disturbances, and the discs eventually stop tilting-impacting once the disturbance subsides, and the system with deformed discs experiences longer recovery times. Furthermore, the tilting-impact forces in systems with deformed discs are smaller than those with flat discs only.

Dynamic substructuring for visco-elastic materials using a POD-based model reduction method: application to laminated panels

Dynamic substructuring is now a well established and powerful tool for engineers used to analyze the dynamic response of mechanical systems. The technique is particularly favored for the simulation of mechanical vibrations allowing different aspects to be studied. It consists in splitting the global structure into several substructures from which reduced models are built. In Finite Element software, these reduced models, also called superelements, are generally built using the concept of Component Mode Synthesis. Difficulties arise when structures made of frequency-dependent materials are considered since classical modal reduction algorithms are inapplicable as they are because of the frequency-dependence of the stiffness matrix. Based on the Balanced Truncation approach, a novel methodology for the construction of a superelement for the dynamic analysis of elastic structures made with viscoelastic materials is presented. The methodology takes advantage of the Golla-Hughes-McTavish rheological model (GHM) before reducing the system via the Balanced Proper Orthogonal Decomposition (BPOD). The coupling of the superelement with a host structure is achieved via the use of Lagrange multipliers. The reduced system takes the form of a constant matrix of very small size compared to the original FE model. The method is applied to laminated panels such as an automobile windscreen.

Dynamic characteristics and damage identification with interface damage of slabs in movable point crossing

As the operating density of China’s high-speed railway increases, the phenomenon of interlayer debonding in movable point crossing (MPC) is becoming more prevalent, which can lead to failure of the frog’s slab track. Meanwhile, vehicle impacts and interlayer debonding can exacerbate abnormal vibration of the vehicle and even lead to derailment. Therefore, based on the theory of rigid-flexible coupling dynamics, a vehicle-turnout-slab coupling dynamics model is established for the first time. In this model, the crossing rails with variable cross sections is considered and the interlayer debonding between turnout slabs is modelled by nonlinear springs. Then, the characteristics of the debonding is identified by applying a wavelet transform to the dynamic response of the vehicle. Finally, different types and sizes of debonding between the layers are considered. The results show that different debonding can lead to two types of contact, partial contact and complete voiding, which can further lead to detrimental effects on vehicle safety. And the limit of the defect size that causes the track slab to void is 1 mm. On this basis, it was found that when MPC’s slab tracks were voided, longer debonding can cause high frequency vibration acceleration of approximately 700 Hz in the vehicle axle box. The new insights obtained by this study could provide guidance for the maintenance period and avoid the development of the damage. This study not only obtained a mechanism for the effect of interlayer debonding on the dynamic response of the vehicle-track system, but also provides a theoretical basis of detecting interlayer debonding for future study.

Seasonal dynamics of chemistry in an Arctic glacier-fed river

Arctic rivers, intricately linked to fjord systems, wield significant influence over the geochemical and biological dynamics of the upper Arctic Ocean, providing it with freshwater, nutrients, suspended particles, and potentially harmful pollutants. To comprehend the full picture of the Arctic ecosystem, it is crucial to understand how these rivers vary across regions and seasons, especially considering ongoing climate changes. However, comprehensive studies that address long-term observations and seasonal variations in Arctic rivers' geochemical composition remain scarce. In this study, we present comprehensive long-term investigations of the seasonal variations in elemental concentrations in Bayelva, a high Arctic glacier-fed river. By analyzing 224 surface water samples, collected during different seasons between 2011 and 2020, we elucidate the diverse influences of marine, geological and atmospheric factors on the river chemistry. Our findings underscore the importance of marine-influenced snowmelt in the early flow season, which leads to elevated concentrations of marine and trace elements in the runoff water at the onset of melting, with concentrations subsequently decreasing as the snow melting continues. Glacial meltwater dominates the river chemistry during the peak flow season, during which elemental concentrations are at their lowest. Late flow season exhibits high elemental concentrations, primarily driven by weathering processes. Additionally, heavy rain and freezing events play a crucial role in sudden alterations in river chemistry. We highlight the dynamic response of Arctic river systems to such environmental drivers as key players in transporting essential micro- and macro-nutrients, as well as potentially harmful pollutants to adjacent fjord systems. Given their susceptibility to climate change, continuous monitoring is essential for understanding future changes. This study provides data for a better foundation for accurate climate modeling of biogeochemical systems in the Arctic environment.