Reducing the effects of external disturbance on overhead crane systems is crucial,as they can impair the controller performance and cause excessive vibrations or oscillations of the payloads.One such external disturba...Reducing the effects of external disturbance on overhead crane systems is crucial,as they can impair the controller performance and cause excessive vibrations or oscillations of the payloads.One such external disturbance is the inclination of the supporting track of the crane trolley,which causes the system dynamics model to change.An open-loop control strategy is widely utilized to control the payload sway motion and generally does not require any alterations in the physical structure of a system or the installation of sensors and/or actuators.Input and command shaping are two common open-loop control techniques applied to control overhead cranes.In this paper,the effect of moving an overhead crane system along an inclined supporting track is investigated.In addition,the ability of different types of input-and command-shaping control schemes to suppress the residual vibrations due to trolley track inclination is demonstrated.Two types of input-shaping controllers,which are double-step,zero vibration,and one command waveform(WF)shaper based on a trigonometric function,are used and tested.A linear equation of motion of the overhead crane resting on an inclined surface is developed to simulate the overhead crane and payload motion.The effectiveness of the different types of open-loop controllers to suppress residual vibrations is verified by both simulation and experimental results.In addition,a new WF command shaper is proposed and designed to overcome track inclination while eliminating payload residual vibration.A comprehensive comparative analysis,both numerically and experimentally,is performed on the new proposed shaper to measure its effectiveness in handling inclination when compared to other types of open-loop controllers.The new shaper outperforms other controllers in eliminating payload residual vibration for a wider range of inclination angles.展开更多
A robust control method for the uncertain vertical electric stabilization system(VESS)with flexible nonlinearity is proposed,and the mismatched uncertainty is considered and compensated based on the backstepping idea....A robust control method for the uncertain vertical electric stabilization system(VESS)with flexible nonlinearity is proposed,and the mismatched uncertainty is considered and compensated based on the backstepping idea.First,based on evaluating the coupling effects of the flexible nonlinearity,the analytical dynamics model of the VESS is established.Second,the tracking error is defined as the evaluation of the system's pitch-pointing tracking control,and then the mismatched state space model with two interconnected subsystems is established as the controlled system.Third,the original mismatched system is converted to the locally matched system using the backstepping design to transform the system state variables.The robust control is proposed to handle the flexible nonlinearity and mismatched uncertainty,which can make both the original system and the reconfigured system present practical stability.Finally,the effectiveness of the proposed control is verified by numerical simulation experiments.This study should be the first to consider flexible nonlinearity coupling and two different uncertainties(matched and mismatched uncertainty)in the design of pitch-pointing tracking control for the vertical electric stabilization system(VESS).展开更多
In recent decades,the design of complex systems like launch vehicles in the aerospace industry has presented engineers with challenges that go beyond system complexity.Issues such as time-to-market pressures and intri...In recent decades,the design of complex systems like launch vehicles in the aerospace industry has presented engineers with challenges that go beyond system complexity.Issues such as time-to-market pressures and intricate industrial processes have underscored the increasing significance of agile design methodologies.Agile design is derived from the simplification of the design process and enhancing cross-domain data transmission and feedback.While methods based on model-based system engineering have improved iteration times in system architecture design,challenges persist in cross-domain data transmission.Due to the diversity of complex system models and data,a single-mode integration method is difficult to realize the data link construction of all tools used.To address this challenge,this paper proposes a dualmode data integration framework with expansibility,universality,and cost-efficiency which leverages the benefits of Remote Procedure Call and Intermediate Exchange Module,addressing the challenge of constructing cross-domain data links under single-mode integration.In this study,two critical requirements of the first-and second-stage separation systems,namely,weight and minimum separation gap,are selected for data feedback.A Modelica-based multiphysics simulation model is developed in MWorks;visualization and computation of the minimum gap are carried out in CoppeliaSim.To bridge the gap between domain-specific tools,Matlab and Functional Mock-up Unit modules are introduced as middleware,facilitating data feedback linkage.The entire simulation process is orchestrated using activity diagrams in the MagicDraw tool.The study delves into the influence of critical design parameters,such as the initial angular velocity of separation and the thrust of the retro rocket,on the minimum separation gap.It provides an analysis of minimum separation gap variations under uncertain operating conditions and examines design margins.Significantly,the paper highlights the significance of controlling the initial angular velocity during separation and the reliability of the retro rocket,providing essential decision supports and valuable insights to agile the process of system design.展开更多
The operation of symmetric double-sided and asymmetric single-sided vibro-impact nonlinear energy sinks(DSVI NES and SSVI NES)is considered in this study.The methodology of optimization procedures is described.It is e...The operation of symmetric double-sided and asymmetric single-sided vibro-impact nonlinear energy sinks(DSVI NES and SSVI NES)is considered in this study.The methodology of optimization procedures is described.It is emphasized that the execution of optimization procedures is ambiguous,allows for a great deal of arbitrariness,and requires experience and intuition on the part of the implementer.There are a lot of damper parameter sets providing similar attenuation of the primary structure(PS)vibrations.It is shown that the efficiency of such mitigation for both VI NES types with optimized parameters is similar.However,their dynamic behavior differs significantly.The system with the attached DSVI NES exhibits calm dynamics with periodic motion and symmetrical bilateral impacts on both obstacles.The system with attached SSVI NES exhibits rich complex dynamics when the exciting force frequency is varied.Periodic modes of different periodicity with different numbers of asymmetric impacts per cycle on the PS directly and on the obstacle alternate with various irregular regimes,namely,chaotic mode,intermittency,and crisis-induced intermittency.The regions of bilateral impacts are narrow and located near resonance;they are narrower for a system with an attached DSVI NES.In a system with an attached SSVI NES,there are wider areas of asymmetric unilateral impacts.展开更多
Flutter is a self‐excited vibration under the interaction of the inertial force,aero-dynamic force,and elastic force of the structure.After the flutter occurs,the aircraft structures will exhibit limit cycle oscillat...Flutter is a self‐excited vibration under the interaction of the inertial force,aero-dynamic force,and elastic force of the structure.After the flutter occurs,the aircraft structures will exhibit limit cycle oscillation,which will cause catastrophic accidents or fatigue damage to the structures.Therefore,it is of great theoretical and practical significance to study the aeroelastic characteristics and flutter control for improving the aeroelastic stability of aircraft structures.This paper reviews the recent advances in aeroelastic analysis and flutter control of wings and panel structures.The me-chanism of aeroelastic flutter of wings and panels is presented.The research methods of aeroelastic flutter for different structures developed in recent years are briefly summarized.Various control strategies including the linear and nonlinear control algorithms as well as the active flutter control results of wings and panels are presented.Finally,the paper ends with conclusions,which highlight challenges of the development in aeroelastic analysis and flutter control,and provide a brief outlook on the future investigations.This study aims to present a comprehensive under-standing of aeroelastic analysis and flutter control.It can also provide guidance on the design of new wings and panel structures for improving their aeroelastic stability.展开更多
During the initial stage of vertical launch,a missile may exhibit an uncertain roll angle(φ)and a high angle of attack(α).This study focuses on examining the impact of roll angle variations on the flow field and the...During the initial stage of vertical launch,a missile may exhibit an uncertain roll angle(φ)and a high angle of attack(α).This study focuses on examining the impact of roll angle variations on the flow field and the unsteady aerodynamics of a canard-configured missile atα=75°.Simulations were performed using the validated k-ωSST turbulence model.The analysis encompasses the temporal development of vortices,the oscillatory characteristics of the lateral force,and the fluctuation of kinetic energy distribution within the framework of proper orthogonal decomposition(POD).The results indicate that the flow field surrounding the canardconfigured missile is characterized by inconsistent shedding cycles of Kármán-like and canard-separated vortices.A distinct transition zone is identified between these vortices,where vortex tearing and reconnection phenomena occur.With increasing roll angles from 0°to 45°,there is an observed shift in the dominant frequency of the lateral force from the higher frequency associated with Kármán-like vortex shedding to the lower frequency of canard vortex shedding.The shedding frequency of Kármán-like vortices corresponds to the harmonics of the canard vortex shedding frequency,indicative of a higher-order harmonic resonance.The frequency of the lateral force is observed to decrease with an increase in roll angle,except in configurations lacking distinct canard-separated vortices,which are characterized by a“+”shape.The POD analysis reveals that the majority of the fluctuation energy is concentrated in the oscillations and shedding of the canard-separated vortices,leading to pressure fluctuations that are primarily observed on the canard and the downstream region of the canard.展开更多
Dear Authors/Reviewers/Editorial Board Members/Editorial Office Members/Readers,We are delighted to inform you that the International Journal of Mechanical System Dynamics(IJMSD)was officially indexed by Emerging Sour...Dear Authors/Reviewers/Editorial Board Members/Editorial Office Members/Readers,We are delighted to inform you that the International Journal of Mechanical System Dynamics(IJMSD)was officially indexed by Emerging Sources Citation Index(ESCI)on June 27,2023,after being indexed by Inspec,Scopus,DOAJ,Dimensions,and some other databases.We would like to take this opportunity,on behalf of the IJMSD Editorial Board,to extend our gratitude and sincere appreciation for your significant contributions and support to IJMSD.展开更多
A new type of piecewise negative stiffness(NS)mechanism is designed and the relationship between the force and displacement is studied.At first,the prototype of the piecewise NS mechanism is established,and the stiffn...A new type of piecewise negative stiffness(NS)mechanism is designed and the relationship between the force and displacement is studied.At first,the prototype of the piecewise NS mechanism is established,and the stiffness characteristic of this mechanism is analyzed.Then,the piecewise NS mechanism is applied to dynamic vibration absorber(DVA)system to establish a dynamic model with the piecewise linearity.The differential motion equations are derived according to Newton's law of mechanics.The approximate analytical solution and the amplitude frequency curve of the system with the piecewise NS are obtained by means of the averaging method.The correctness of the analytical solution is proved by comparing with the numerical solution.In the end,the comparisons with two other traditional DVAs show that the system in this paper has better vibration reduction effect under the condition of harmonic excitation and random excitation.展开更多
The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research t...The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research topic.To address the limitations of the“instantaneous engraving”hypothesis adopted in the classical interior ballistic theory,the VUAMP user subroutine,one of ABAQUS's secondary development interfaces,is utilized in this paper to realize the modeling and numerical simulation of a coupled dynamics model of the projectile engraving process.In addition to facilitating engineering applications,a polynomial fitting formula of the engraving resistance obtained by simulation is proposed and then used as a supplement to establish a closed and solvable interior ballistic model considering the projectile engraving process.By comparing with test data,the simulation accuracy of the coupled dynamics model is verified.Simulation results reveal that the engraving process takes 3.8 ms,accounting for 26%of the whole launch process,which takes 14.6 ms,demonstrating that the process is not instantaneous.The results of this paper can serve as a reference for future studies on the coupled solution of the projectile engraving process and interior ballistics of guns or gun-like equipment.展开更多
Sparse subspace clustering(SSC)is a spectral clustering methodology.Since high-dimensional data are often dispersed over the union of many low-dimensional subspaces,their representation in a suitable dictionary is spa...Sparse subspace clustering(SSC)is a spectral clustering methodology.Since high-dimensional data are often dispersed over the union of many low-dimensional subspaces,their representation in a suitable dictionary is sparse.Therefore,SSC is an effective technology for diagnosing mechanical system faults.Its main purpose is to create a representation model that can reveal the real subspace structure of high-dimensional data,construct a similarity matrix by using the sparse representation coefficients of high-dimensional data,and then cluster the obtained representation coefficients and similarity matrix in subspace.However,the design of SSC algorithm is based on global expression in which each data point is represented by all possible cluster data points.This leads to nonzero terms in nondiagonal blocks of similar matrices,which reduces the recognition performance of matrices.To improve the clustering ability of SSC for rolling bearing and the robustness of the algorithm in the presence of a large number of background noise,a simultaneous dimensionality reduction subspace clustering technology is provided in this work.Through the feature extraction of envelope signal,the dimension of the feature matrix is reduced by singular value decomposition,and the Euclidean distance between samples is replaced by correlation distance.A dimension reduction graph-based SSC technology is established.Simulation and bearing data of Western Reserve University show that the proposed algorithm can improve the accuracy and compactness of clustering.展开更多
Tracking control of multibody systems is a challenging task requiring detailed modeling and control expertise. Especially in the case of closed-loop mechanisms, inverse kinematics as part of the controller may become ...Tracking control of multibody systems is a challenging task requiring detailed modeling and control expertise. Especially in the case of closed-loop mechanisms, inverse kinematics as part of the controller may become a game stopper due to the extensive calculations required for solving nonlinear equations and inverting complicated functions. The procedure introduced in this paper substitutes such advanced human expertise by artificial intelligence through the utilization of surrogates, which may be trained from data obtained by classical simulation. The necessary steps are demonstrated along a parallel mechanism called λ-robot. Based on its mechanical model, the workspace is investigated, which is required to set proper initial conditions for generating data covering the used operation space of the robot. Based on these data, artificial neural networks are trained as surrogates for inverse kinematics and inverse dynamics. They provide forward control information such that the remaining error behavior is governed by a linear ordinary differential equation, which allows applying a linear quadratic regulator (LQR) from linear control theory. An additional feedback loop of the tracking error accounts for model uncertainties. Simulation results validate the applicability of the proposed concept.展开更多
This paper summarizes the progress of machine-learning-based interatomic potentials and their applications in advanced manufacturing.Interatomic potential is essential for classical molecular dynamics.The advancements...This paper summarizes the progress of machine-learning-based interatomic potentials and their applications in advanced manufacturing.Interatomic potential is essential for classical molecular dynamics.The advancements made in machine learning(ML)have enabled the development of fast interatomic potential with ab initio accuracy.The accelerated atomic simulation can greatly transform the design principle of manufacturing technology.The most widely used supervised and unsupervised ML methods are summarized and compared.Then,the emerging interatomic models based on ML are discussed:Gaussian approximation potential,spectral neighbor analysis potential,deep potential molecular dynamics,SCHNET,hierarchically interacting particle neural network,and fast learning of atomistic rare events.展开更多
To improve the dynamic balancing accuracy of the micro-motor rotor,an unbalanced vibration feature extraction based on an all-phase fast Fourier transform(APFFT)method is proposed.The amplitude and phase of the signal...To improve the dynamic balancing accuracy of the micro-motor rotor,an unbalanced vibration feature extraction based on an all-phase fast Fourier transform(APFFT)method is proposed.The amplitude and phase of the signal are extracted by spectrum analysis after windowing the unbalanced signal.The mathematical model is derived to simulate the weak signal of rotor unbalance.The simulation results show that this method is accurate in extracting the weak signal of the rotor under different noise levels.The micro-motor rotor unbalanced test system is developed for experimental validations.The accuracy and stability of the vibration amplitude and phase extracted by the APFFT are better than the accuracy and stability from the hardware filtering method.The rotor unbalance is reduced by more than 80%.Furthermore,secondary balance of the rotor after the first balance is carried out.The proposed method can still extract the residual unbalance of the rotor.The results demonstrated that the proposed method can achieve a reduction rate of 90%and the accuracy is within 5mg,verifying the effectiveness of the proposed method for high-precision rotor dynamic balance.展开更多
Considerable research has indicated that fiber‐reinforced textile composites are significantly beneficial to the aerospace industry,especially aero engines,due to their high specific strength,specific stiffness,corro...Considerable research has indicated that fiber‐reinforced textile composites are significantly beneficial to the aerospace industry,especially aero engines,due to their high specific strength,specific stiffness,corrosion resistance,and fatigue re-sistance.However,damage caused by high‐velocity impacts is a critical limitation factor in a wide range of applications.This paper presents an overview of the development,material characterizations,and applications of fiber‐reinforced textile composites for aero engines.These textile composites are classified into four ca-tegories including two‐dimensional(2D)woven composites,2D braided composites,3D woven composites,and 3D braided composites.The complex damage me-chanisms of these composite materials due to high‐velocity impacts are discussed in detail as well.展开更多
To address the difficulty in extracting early fault feature signals of rolling bearings,this paper proposes a novel weak fault diagnosis method for rolling bearings.This method combines the Improved Complementary Ense...To address the difficulty in extracting early fault feature signals of rolling bearings,this paper proposes a novel weak fault diagnosis method for rolling bearings.This method combines the Improved Complementary Ensemble Empirical Mode Decomposition with Adaptive Noise(ICEEMDAN)and the Improved Maximum Correlated Kurtosis Deconvolution(IMCKD).Utilizing the kurtosis criterion,the intrinsic mode functions obtained through ICEEMDAN are reconstructed and denoised using IMCKD,which significantly reduces noise in the measured signal.This approach maximizes the energy amplitude at the fault characteristic frequency,facilitating fault feature identification.Experimental studies on two test benches demonstrate that this method effectively reduces noise interference and highlights the fault frequency components.Compared with traditional methods,it significantly improves the signal-to-noise ratio and more accurately identifies fault features,meeting the requirements for discriminating rolling bearing faults.The method proposed in this study was applied to the measured vibration signals of the gearbox bearings in the new high-speed wire department of a Long Products Mill.It successfully extracted weak characteristic information of early bearing faults,achieving the expected diagnostic results.This further validates the effectiveness of the ICEEMDAN–IMCKD method in practical engineering applications,demonstrating significant engineering value for detecting and extracting weak impact characteristics in rolling bearings.展开更多
Electrically assisted turbochargers(EAT)improve intake efficiency by motor-assisted compressor impeller rotation,enhancing the system's transient response.However,the addition of motor rotor components has increas...Electrically assisted turbochargers(EAT)improve intake efficiency by motor-assisted compressor impeller rotation,enhancing the system's transient response.However,the addition of motor rotor components has increased the number of unbalanced positions in the shaft system,leading to problems such as excessive compressor end vibration and complex changes in oil film stability.To evaluate the effects of unbalance in the motor rotor,along with the parameters of floating ring bearings(FRB),on the dynamic response of EAT,a finite element model of an EAT rotor supported by nonlinear FRB is developed,and the vibration response of the compressor end bearing is obtained by numerical integration.The results indicate:(1)In contrast to the effect of compressor and turbine unbalance,proper motor rotor unbalance is more effective in suppressing oil whirl instability in the high-speed operating range.However,a new inner oil film whirl“instability interval”is also induced in the low-speed operating range,leading to an increase in the Y1 compressor-end amplitude at low and medium speeds,and this“instability interval”increases with the amount of unbalance.(2)When an oil whirl occurs in the oil film,the maximum eccentricity of the bearing surges and is greater than 0.3,which can be used as an effective threshold for determining whether the oil film is unstable in engineering applications.(3)A suitable outer oil-film clearance range should be 35–40μm,otherwise,a wide range of outer oil-film whirl instability occurs.Controlling the amount of unbalance and oil-film clearance to suppress the subsynchronous vibration of the EAT,provides a theoretical basis for the design of the dynamics of the nonlinear rotor bearing system and improves the stability of the turbocharger's operation.展开更多
To obtain accurate fatigue life results for construction machinery components,acquiring load spectra is crucial,as their authenticity and validity directly determine the precision of the analysis.In working conditions...To obtain accurate fatigue life results for construction machinery components,acquiring load spectra is crucial,as their authenticity and validity directly determine the precision of the analysis.In working conditions,component attitudes change continuously,but they remain static on the vibration test rig(VTR),so the acquired target signals should match with the actual component attitudes in the driving signal generation.This paper proposes an efficient and economical simulation-based virtual VTR for fatigue analysis of dozers.First,the relationship between the push arm rotation angle and the cylinder stroke is established,since the cylinder strokes can be measured easily in data acquisition experiments.Second,load decomposition is used to determine the attitude relationship between virtual VTR conditions and actual conditions,and target signals are calculated based on this attitude relationship and measured data.According to the system's frequency response function,the driving signals are iterated until the system's response signals converge with the target signals.Finally,the iteratively obtained load spectra are utilized for fatigue life analysis.The results show that the virtual VTR can effectively and accurately obtain the results of fatigue analysis and has engineering application significance.展开更多
This study aims to show an approach for the dynamic simulation of a synchro-nous machine.The magnetic forces in the air gap are calculated efficiently using simplified approaches without neglecting important effects.F...This study aims to show an approach for the dynamic simulation of a synchro-nous machine.The magnetic forces in the air gap are calculated efficiently using simplified approaches without neglecting important effects.For the modeling of the magnetic forces,an equivalent magnetic circuit is constructed in which the magnetic saturation and the leakage flux are taken into account and coupled with the electrical circuit at the end.The calculated magnetic forces are then passed to a mechanical model of the motor.Together with a predefinable load torque,the resulting motor rotation and the forces in the bearings are identified.The presented model is then investigated in a small example.This novel ap-proach is intended to provide a method of calculating dynamically the forces transmitted from the shaft to the motor housing and to create the basis for evaluating electric motors for vibrations,noise,and harshness under varying loads and input voltages.展开更多
Nonlinearity in parallel compliance can be exploited to improve the performance of locomotion systems in terms of(1)energy efficiency,(2)control robustness,and(3)gait optimality;that is,attaining energy efficiency acr...Nonlinearity in parallel compliance can be exploited to improve the performance of locomotion systems in terms of(1)energy efficiency,(2)control robustness,and(3)gait optimality;that is,attaining energy efficiency across a set of motions.Thus far,the literature has investigated and validated only the first two benefits.In this study,we present a new mathematical framework for designing nonlinear compliances in cyclic tasks encompassing all three benefits.We present an optimization-based formulation for each benefit to obtain the desired compliance profile.Furthermore,we analytically prove that,compared to linear compliance,using nonlinear compliance leads to(1)lower energy consumption,(2)better closed-loop performance,specifically in terms of tracking error,and(3)a higher diversity of natural frequencies.To compare the performance of linear and nonlinear compliance,we apply the proposed methods to a diverse set of robotic systems performing cyclic tasks,including a 2-DOF manipulator,a 3-DOF bipedal walker,and a hopper model.Compared to linear compliance,the nonlinear compliance leads to better performance in all aspects;for example,a 70%reduction in energy consumption and tracking error for the manipulator simulation.Regarding gait optimality,for all robotic simulation models,compared to linear compliance,the nonlinear compliance has lower energy consumption and tracking error over the considered set of motions.The proposed analytical studies and simulation results strongly support the idea that using nonlinear compliance significantly improves robotic system performance in terms of energy efficiency,control robustness,and gait optimality.展开更多
Pyrotechnic devices are widely used in the aerospace and defense industries.However,these devices generate high-frequency and high-amplitude shock responses during their use,compromising safe operation of the system.I...Pyrotechnic devices are widely used in the aerospace and defense industries.However,these devices generate high-frequency and high-amplitude shock responses during their use,compromising safe operation of the system.In this paper,the application of a thin-walled circular tube as the energy absorber in pyrotechnic devices is investigated.To accurately predict the shock load and the buffer performance of the thin-walled circular tube,a coupled model connecting the energetic material combustion and finite element simulation is established.The validity of the coupled model is verified by comparing with experiments.Then,the collapse mechanism of the thin-walled circular tube is studied,and the influence of multiple structural parameters on its buffer performance is analyzed.The results show that the thin-walled circular tube effectively reduces the shock overload.The maximum shock overload reduced from 572612g to 11204g in the studied case.The structural parameters of the thin-walled circular tube mainly affect the deformation process and the maximum shock overload.The order of importance of structural parameters to the maximum shock overload is determined,among which the wall thickness has the most significant effect.展开更多
文摘Reducing the effects of external disturbance on overhead crane systems is crucial,as they can impair the controller performance and cause excessive vibrations or oscillations of the payloads.One such external disturbance is the inclination of the supporting track of the crane trolley,which causes the system dynamics model to change.An open-loop control strategy is widely utilized to control the payload sway motion and generally does not require any alterations in the physical structure of a system or the installation of sensors and/or actuators.Input and command shaping are two common open-loop control techniques applied to control overhead cranes.In this paper,the effect of moving an overhead crane system along an inclined supporting track is investigated.In addition,the ability of different types of input-and command-shaping control schemes to suppress the residual vibrations due to trolley track inclination is demonstrated.Two types of input-shaping controllers,which are double-step,zero vibration,and one command waveform(WF)shaper based on a trigonometric function,are used and tested.A linear equation of motion of the overhead crane resting on an inclined surface is developed to simulate the overhead crane and payload motion.The effectiveness of the different types of open-loop controllers to suppress residual vibrations is verified by both simulation and experimental results.In addition,a new WF command shaper is proposed and designed to overcome track inclination while eliminating payload residual vibration.A comprehensive comparative analysis,both numerically and experimentally,is performed on the new proposed shaper to measure its effectiveness in handling inclination when compared to other types of open-loop controllers.The new shaper outperforms other controllers in eliminating payload residual vibration for a wider range of inclination angles.
文摘A robust control method for the uncertain vertical electric stabilization system(VESS)with flexible nonlinearity is proposed,and the mismatched uncertainty is considered and compensated based on the backstepping idea.First,based on evaluating the coupling effects of the flexible nonlinearity,the analytical dynamics model of the VESS is established.Second,the tracking error is defined as the evaluation of the system's pitch-pointing tracking control,and then the mismatched state space model with two interconnected subsystems is established as the controlled system.Third,the original mismatched system is converted to the locally matched system using the backstepping design to transform the system state variables.The robust control is proposed to handle the flexible nonlinearity and mismatched uncertainty,which can make both the original system and the reconfigured system present practical stability.Finally,the effectiveness of the proposed control is verified by numerical simulation experiments.This study should be the first to consider flexible nonlinearity coupling and two different uncertainties(matched and mismatched uncertainty)in the design of pitch-pointing tracking control for the vertical electric stabilization system(VESS).
基金National Key Research and Development Program of China,Grant/Award Number:2020YFB1708100“14th Five-Year Plan”Civil Aerospace Pre-research Project of China,Grant/Award Number:D020101。
文摘In recent decades,the design of complex systems like launch vehicles in the aerospace industry has presented engineers with challenges that go beyond system complexity.Issues such as time-to-market pressures and intricate industrial processes have underscored the increasing significance of agile design methodologies.Agile design is derived from the simplification of the design process and enhancing cross-domain data transmission and feedback.While methods based on model-based system engineering have improved iteration times in system architecture design,challenges persist in cross-domain data transmission.Due to the diversity of complex system models and data,a single-mode integration method is difficult to realize the data link construction of all tools used.To address this challenge,this paper proposes a dualmode data integration framework with expansibility,universality,and cost-efficiency which leverages the benefits of Remote Procedure Call and Intermediate Exchange Module,addressing the challenge of constructing cross-domain data links under single-mode integration.In this study,two critical requirements of the first-and second-stage separation systems,namely,weight and minimum separation gap,are selected for data feedback.A Modelica-based multiphysics simulation model is developed in MWorks;visualization and computation of the minimum gap are carried out in CoppeliaSim.To bridge the gap between domain-specific tools,Matlab and Functional Mock-up Unit modules are introduced as middleware,facilitating data feedback linkage.The entire simulation process is orchestrated using activity diagrams in the MagicDraw tool.The study delves into the influence of critical design parameters,such as the initial angular velocity of separation and the thrust of the retro rocket,on the minimum separation gap.It provides an analysis of minimum separation gap variations under uncertain operating conditions and examines design margins.Significantly,the paper highlights the significance of controlling the initial angular velocity during separation and the reliability of the retro rocket,providing essential decision supports and valuable insights to agile the process of system design.
文摘The operation of symmetric double-sided and asymmetric single-sided vibro-impact nonlinear energy sinks(DSVI NES and SSVI NES)is considered in this study.The methodology of optimization procedures is described.It is emphasized that the execution of optimization procedures is ambiguous,allows for a great deal of arbitrariness,and requires experience and intuition on the part of the implementer.There are a lot of damper parameter sets providing similar attenuation of the primary structure(PS)vibrations.It is shown that the efficiency of such mitigation for both VI NES types with optimized parameters is similar.However,their dynamic behavior differs significantly.The system with the attached DSVI NES exhibits calm dynamics with periodic motion and symmetrical bilateral impacts on both obstacles.The system with attached SSVI NES exhibits rich complex dynamics when the exciting force frequency is varied.Periodic modes of different periodicity with different numbers of asymmetric impacts per cycle on the PS directly and on the obstacle alternate with various irregular regimes,namely,chaotic mode,intermittency,and crisis-induced intermittency.The regions of bilateral impacts are narrow and located near resonance;they are narrower for a system with an attached DSVI NES.In a system with an attached SSVI NES,there are wider areas of asymmetric unilateral impacts.
基金National Natural Science Foundation of China,Grant/Award Numbers:12072083,11761131006German Research Foundation,Grant/Award Number:ZH 15/30‐1。
文摘Flutter is a self‐excited vibration under the interaction of the inertial force,aero-dynamic force,and elastic force of the structure.After the flutter occurs,the aircraft structures will exhibit limit cycle oscillation,which will cause catastrophic accidents or fatigue damage to the structures.Therefore,it is of great theoretical and practical significance to study the aeroelastic characteristics and flutter control for improving the aeroelastic stability of aircraft structures.This paper reviews the recent advances in aeroelastic analysis and flutter control of wings and panel structures.The me-chanism of aeroelastic flutter of wings and panels is presented.The research methods of aeroelastic flutter for different structures developed in recent years are briefly summarized.Various control strategies including the linear and nonlinear control algorithms as well as the active flutter control results of wings and panels are presented.Finally,the paper ends with conclusions,which highlight challenges of the development in aeroelastic analysis and flutter control,and provide a brief outlook on the future investigations.This study aims to present a comprehensive under-standing of aeroelastic analysis and flutter control.It can also provide guidance on the design of new wings and panel structures for improving their aeroelastic stability.
基金Fund of Science and Technology on Underwater Information and Control Laboratory,Grant/Award Number:2021-JCJQ-LB-030-05。
文摘During the initial stage of vertical launch,a missile may exhibit an uncertain roll angle(φ)and a high angle of attack(α).This study focuses on examining the impact of roll angle variations on the flow field and the unsteady aerodynamics of a canard-configured missile atα=75°.Simulations were performed using the validated k-ωSST turbulence model.The analysis encompasses the temporal development of vortices,the oscillatory characteristics of the lateral force,and the fluctuation of kinetic energy distribution within the framework of proper orthogonal decomposition(POD).The results indicate that the flow field surrounding the canardconfigured missile is characterized by inconsistent shedding cycles of Kármán-like and canard-separated vortices.A distinct transition zone is identified between these vortices,where vortex tearing and reconnection phenomena occur.With increasing roll angles from 0°to 45°,there is an observed shift in the dominant frequency of the lateral force from the higher frequency associated with Kármán-like vortex shedding to the lower frequency of canard vortex shedding.The shedding frequency of Kármán-like vortices corresponds to the harmonics of the canard vortex shedding frequency,indicative of a higher-order harmonic resonance.The frequency of the lateral force is observed to decrease with an increase in roll angle,except in configurations lacking distinct canard-separated vortices,which are characterized by a“+”shape.The POD analysis reveals that the majority of the fluctuation energy is concentrated in the oscillations and shedding of the canard-separated vortices,leading to pressure fluctuations that are primarily observed on the canard and the downstream region of the canard.
文摘Dear Authors/Reviewers/Editorial Board Members/Editorial Office Members/Readers,We are delighted to inform you that the International Journal of Mechanical System Dynamics(IJMSD)was officially indexed by Emerging Sources Citation Index(ESCI)on June 27,2023,after being indexed by Inspec,Scopus,DOAJ,Dimensions,and some other databases.We would like to take this opportunity,on behalf of the IJMSD Editorial Board,to extend our gratitude and sincere appreciation for your significant contributions and support to IJMSD.
基金The authors are grateful to the support by National Natural Science Foundation of China(No.U1934201 and 11772206).
文摘A new type of piecewise negative stiffness(NS)mechanism is designed and the relationship between the force and displacement is studied.At first,the prototype of the piecewise NS mechanism is established,and the stiffness characteristic of this mechanism is analyzed.Then,the piecewise NS mechanism is applied to dynamic vibration absorber(DVA)system to establish a dynamic model with the piecewise linearity.The differential motion equations are derived according to Newton's law of mechanics.The approximate analytical solution and the amplitude frequency curve of the system with the piecewise NS are obtained by means of the averaging method.The correctness of the analytical solution is proved by comparing with the numerical solution.In the end,the comparisons with two other traditional DVAs show that the system in this paper has better vibration reduction effect under the condition of harmonic excitation and random excitation.
基金National Natural Science Foundation of China,Grant/Award Number:12372093。
文摘The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research topic.To address the limitations of the“instantaneous engraving”hypothesis adopted in the classical interior ballistic theory,the VUAMP user subroutine,one of ABAQUS's secondary development interfaces,is utilized in this paper to realize the modeling and numerical simulation of a coupled dynamics model of the projectile engraving process.In addition to facilitating engineering applications,a polynomial fitting formula of the engraving resistance obtained by simulation is proposed and then used as a supplement to establish a closed and solvable interior ballistic model considering the projectile engraving process.By comparing with test data,the simulation accuracy of the coupled dynamics model is verified.Simulation results reveal that the engraving process takes 3.8 ms,accounting for 26%of the whole launch process,which takes 14.6 ms,demonstrating that the process is not instantaneous.The results of this paper can serve as a reference for future studies on the coupled solution of the projectile engraving process and interior ballistics of guns or gun-like equipment.
基金The present work is supported by the National Key R&D Program(No.2020YFB2007700)the National Natural Science Foundation of China(Nos.11790282,11802184,11902205,12002221,12032017)+1 种基金the S&T Program of Hebei(No.20310803D)the Natural Science Foundation of Hebei Province(No.A2020210028).
文摘Sparse subspace clustering(SSC)is a spectral clustering methodology.Since high-dimensional data are often dispersed over the union of many low-dimensional subspaces,their representation in a suitable dictionary is sparse.Therefore,SSC is an effective technology for diagnosing mechanical system faults.Its main purpose is to create a representation model that can reveal the real subspace structure of high-dimensional data,construct a similarity matrix by using the sparse representation coefficients of high-dimensional data,and then cluster the obtained representation coefficients and similarity matrix in subspace.However,the design of SSC algorithm is based on global expression in which each data point is represented by all possible cluster data points.This leads to nonzero terms in nondiagonal blocks of similar matrices,which reduces the recognition performance of matrices.To improve the clustering ability of SSC for rolling bearing and the robustness of the algorithm in the presence of a large number of background noise,a simultaneous dimensionality reduction subspace clustering technology is provided in this work.Through the feature extraction of envelope signal,the dimension of the feature matrix is reduced by singular value decomposition,and the Euclidean distance between samples is replaced by correlation distance.A dimension reduction graph-based SSC technology is established.Simulation and bearing data of Western Reserve University show that the proposed algorithm can improve the accuracy and compactness of clustering.
基金funded by Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)within the primal program SPP 2353 under project no.501840485。
文摘Tracking control of multibody systems is a challenging task requiring detailed modeling and control expertise. Especially in the case of closed-loop mechanisms, inverse kinematics as part of the controller may become a game stopper due to the extensive calculations required for solving nonlinear equations and inverting complicated functions. The procedure introduced in this paper substitutes such advanced human expertise by artificial intelligence through the utilization of surrogates, which may be trained from data obtained by classical simulation. The necessary steps are demonstrated along a parallel mechanism called λ-robot. Based on its mechanical model, the workspace is investigated, which is required to set proper initial conditions for generating data covering the used operation space of the robot. Based on these data, artificial neural networks are trained as surrogates for inverse kinematics and inverse dynamics. They provide forward control information such that the remaining error behavior is governed by a linear ordinary differential equation, which allows applying a linear quadratic regulator (LQR) from linear control theory. An additional feedback loop of the tracking error accounts for model uncertainties. Simulation results validate the applicability of the proposed concept.
基金This study was supported by the Wuhan University Junior Faculty Research(2042019KF0003)the National Natural Science Foundation of China(51727901,U1501241,and 62174122)+1 种基金the National Key R&D Program of China(2017YFB1103904)the Hubei Provincial Natural Science Foundation of China(2020CFA032).
文摘This paper summarizes the progress of machine-learning-based interatomic potentials and their applications in advanced manufacturing.Interatomic potential is essential for classical molecular dynamics.The advancements made in machine learning(ML)have enabled the development of fast interatomic potential with ab initio accuracy.The accelerated atomic simulation can greatly transform the design principle of manufacturing technology.The most widely used supervised and unsupervised ML methods are summarized and compared.Then,the emerging interatomic models based on ML are discussed:Gaussian approximation potential,spectral neighbor analysis potential,deep potential molecular dynamics,SCHNET,hierarchically interacting particle neural network,and fast learning of atomistic rare events.
基金National Natural Science Foundation of China,Grant/Award Numbers:52202445,11602112。
文摘To improve the dynamic balancing accuracy of the micro-motor rotor,an unbalanced vibration feature extraction based on an all-phase fast Fourier transform(APFFT)method is proposed.The amplitude and phase of the signal are extracted by spectrum analysis after windowing the unbalanced signal.The mathematical model is derived to simulate the weak signal of rotor unbalance.The simulation results show that this method is accurate in extracting the weak signal of the rotor under different noise levels.The micro-motor rotor unbalanced test system is developed for experimental validations.The accuracy and stability of the vibration amplitude and phase extracted by the APFFT are better than the accuracy and stability from the hardware filtering method.The rotor unbalance is reduced by more than 80%.Furthermore,secondary balance of the rotor after the first balance is carried out.The proposed method can still extract the residual unbalance of the rotor.The results demonstrated that the proposed method can achieve a reduction rate of 90%and the accuracy is within 5mg,verifying the effectiveness of the proposed method for high-precision rotor dynamic balance.
基金The National Natural Science Foundation of China,Grant/Award Number:12002265China Postdoctoral Science Foundation,Grant/Award Number:2021M692572+1 种基金supported by the National Natural Science Foundation of China(Grant No.:12002265)the China Postdoctoral Science Foundation(Grant No.:2021M692572).
文摘Considerable research has indicated that fiber‐reinforced textile composites are significantly beneficial to the aerospace industry,especially aero engines,due to their high specific strength,specific stiffness,corrosion resistance,and fatigue re-sistance.However,damage caused by high‐velocity impacts is a critical limitation factor in a wide range of applications.This paper presents an overview of the development,material characterizations,and applications of fiber‐reinforced textile composites for aero engines.These textile composites are classified into four ca-tegories including two‐dimensional(2D)woven composites,2D braided composites,3D woven composites,and 3D braided composites.The complex damage me-chanisms of these composite materials due to high‐velocity impacts are discussed in detail as well.
基金Inner Mongolia Autonomous Region Science and Technology Major Special Project,Grant/Award Number:2021ZD0019-4。
文摘To address the difficulty in extracting early fault feature signals of rolling bearings,this paper proposes a novel weak fault diagnosis method for rolling bearings.This method combines the Improved Complementary Ensemble Empirical Mode Decomposition with Adaptive Noise(ICEEMDAN)and the Improved Maximum Correlated Kurtosis Deconvolution(IMCKD).Utilizing the kurtosis criterion,the intrinsic mode functions obtained through ICEEMDAN are reconstructed and denoised using IMCKD,which significantly reduces noise in the measured signal.This approach maximizes the energy amplitude at the fault characteristic frequency,facilitating fault feature identification.Experimental studies on two test benches demonstrate that this method effectively reduces noise interference and highlights the fault frequency components.Compared with traditional methods,it significantly improves the signal-to-noise ratio and more accurately identifies fault features,meeting the requirements for discriminating rolling bearing faults.The method proposed in this study was applied to the measured vibration signals of the gearbox bearings in the new high-speed wire department of a Long Products Mill.It successfully extracted weak characteristic information of early bearing faults,achieving the expected diagnostic results.This further validates the effectiveness of the ICEEMDAN–IMCKD method in practical engineering applications,demonstrating significant engineering value for detecting and extracting weak impact characteristics in rolling bearings.
文摘Electrically assisted turbochargers(EAT)improve intake efficiency by motor-assisted compressor impeller rotation,enhancing the system's transient response.However,the addition of motor rotor components has increased the number of unbalanced positions in the shaft system,leading to problems such as excessive compressor end vibration and complex changes in oil film stability.To evaluate the effects of unbalance in the motor rotor,along with the parameters of floating ring bearings(FRB),on the dynamic response of EAT,a finite element model of an EAT rotor supported by nonlinear FRB is developed,and the vibration response of the compressor end bearing is obtained by numerical integration.The results indicate:(1)In contrast to the effect of compressor and turbine unbalance,proper motor rotor unbalance is more effective in suppressing oil whirl instability in the high-speed operating range.However,a new inner oil film whirl“instability interval”is also induced in the low-speed operating range,leading to an increase in the Y1 compressor-end amplitude at low and medium speeds,and this“instability interval”increases with the amount of unbalance.(2)When an oil whirl occurs in the oil film,the maximum eccentricity of the bearing surges and is greater than 0.3,which can be used as an effective threshold for determining whether the oil film is unstable in engineering applications.(3)A suitable outer oil-film clearance range should be 35–40μm,otherwise,a wide range of outer oil-film whirl instability occurs.Controlling the amount of unbalance and oil-film clearance to suppress the subsynchronous vibration of the EAT,provides a theoretical basis for the design of the dynamics of the nonlinear rotor bearing system and improves the stability of the turbocharger's operation.
基金Shandong Province Science and Technology SMES innovation ability improvement project and Rizhao Key Research and Development Project,Grant/Award Number:2022TSGC2504National Natural Science Foundation of China,Grant/Award Number:52378402+1 种基金Shandong Provincial Natural Science Foundation Youth Project,Grant/Award Numbers:ZR2022QE021,ZR202211100077Taishan Scholar Project,Grant/Award Number:tsqn202312024。
文摘To obtain accurate fatigue life results for construction machinery components,acquiring load spectra is crucial,as their authenticity and validity directly determine the precision of the analysis.In working conditions,component attitudes change continuously,but they remain static on the vibration test rig(VTR),so the acquired target signals should match with the actual component attitudes in the driving signal generation.This paper proposes an efficient and economical simulation-based virtual VTR for fatigue analysis of dozers.First,the relationship between the push arm rotation angle and the cylinder stroke is established,since the cylinder strokes can be measured easily in data acquisition experiments.Second,load decomposition is used to determine the attitude relationship between virtual VTR conditions and actual conditions,and target signals are calculated based on this attitude relationship and measured data.According to the system's frequency response function,the driving signals are iterated until the system's response signals converge with the target signals.Finally,the iteratively obtained load spectra are utilized for fatigue life analysis.The results show that the virtual VTR can effectively and accurately obtain the results of fatigue analysis and has engineering application significance.
基金Ministry of Science,Research,and Arts of the Federal State of Baden‐Württemberg:ReMos project‘Effiziente Reluktanzmaschine für emissionsfreie Mobilität ohne seltene Erden’。
文摘This study aims to show an approach for the dynamic simulation of a synchro-nous machine.The magnetic forces in the air gap are calculated efficiently using simplified approaches without neglecting important effects.For the modeling of the magnetic forces,an equivalent magnetic circuit is constructed in which the magnetic saturation and the leakage flux are taken into account and coupled with the electrical circuit at the end.The calculated magnetic forces are then passed to a mechanical model of the motor.Together with a predefinable load torque,the resulting motor rotation and the forces in the bearings are identified.The presented model is then investigated in a small example.This novel ap-proach is intended to provide a method of calculating dynamically the forces transmitted from the shaft to the motor housing and to create the basis for evaluating electric motors for vibrations,noise,and harshness under varying loads and input voltages.
基金the University of Tehran for providing support with this study.
文摘Nonlinearity in parallel compliance can be exploited to improve the performance of locomotion systems in terms of(1)energy efficiency,(2)control robustness,and(3)gait optimality;that is,attaining energy efficiency across a set of motions.Thus far,the literature has investigated and validated only the first two benefits.In this study,we present a new mathematical framework for designing nonlinear compliances in cyclic tasks encompassing all three benefits.We present an optimization-based formulation for each benefit to obtain the desired compliance profile.Furthermore,we analytically prove that,compared to linear compliance,using nonlinear compliance leads to(1)lower energy consumption,(2)better closed-loop performance,specifically in terms of tracking error,and(3)a higher diversity of natural frequencies.To compare the performance of linear and nonlinear compliance,we apply the proposed methods to a diverse set of robotic systems performing cyclic tasks,including a 2-DOF manipulator,a 3-DOF bipedal walker,and a hopper model.Compared to linear compliance,the nonlinear compliance leads to better performance in all aspects;for example,a 70%reduction in energy consumption and tracking error for the manipulator simulation.Regarding gait optimality,for all robotic simulation models,compared to linear compliance,the nonlinear compliance has lower energy consumption and tracking error over the considered set of motions.The proposed analytical studies and simulation results strongly support the idea that using nonlinear compliance significantly improves robotic system performance in terms of energy efficiency,control robustness,and gait optimality.
文摘Pyrotechnic devices are widely used in the aerospace and defense industries.However,these devices generate high-frequency and high-amplitude shock responses during their use,compromising safe operation of the system.In this paper,the application of a thin-walled circular tube as the energy absorber in pyrotechnic devices is investigated.To accurately predict the shock load and the buffer performance of the thin-walled circular tube,a coupled model connecting the energetic material combustion and finite element simulation is established.The validity of the coupled model is verified by comparing with experiments.Then,the collapse mechanism of the thin-walled circular tube is studied,and the influence of multiple structural parameters on its buffer performance is analyzed.The results show that the thin-walled circular tube effectively reduces the shock overload.The maximum shock overload reduced from 572612g to 11204g in the studied case.The structural parameters of the thin-walled circular tube mainly affect the deformation process and the maximum shock overload.The order of importance of structural parameters to the maximum shock overload is determined,among which the wall thickness has the most significant effect.
