Coupled Dynamic Analysis Research Articles

Dynamic Coupling Analysis on Thermo–Chemo–Mechanical Field and Fluid–Structure Interaction for Aero-Engine Turbine Blade with Functional Gradient Thermal Barrier Coatings

In this study, an extended layerwise/solid-element (XLW/SE) method is developed for the thermo–chemo–mechanical (TCM) coupling problem of an aero-engine turbine blade with thermal barrier coatings (TBCs). The method consists of two parts, the extended layerwise (XLW) method and the three-dimensional (3D) solid-element (SE) method, which are adopted to formulate the governing equations of TBCs and substrate, respectively. Then, according to the compatibility conditions of displacement, temperature, concentration and internal force equilibrium at the TBCs/substrate interface, the governing equation of the final blade structure is assembled. Through a time integration, the dynamic responses of displacement, temperature and concentration can be calculated. In addition, the fluid–structure coupling analysis is conducted by using COMSOL. The nonuniform thermal load is imported into the XLW/SE method to calculate the mechanical response of blade structure. Finally, the corresponding computing program is compiled with C++. In numerical examples, the TCM coupling analysis is conducted on the blade structure with and without interfacial debonding and delamination damages. To validate the effectiveness of the proposed method, the dynamic TCM responses of the XLW/SE model is compared with those of a 3D elastic model generated by COMSOL, which shows that the two models are in good agreement.

Modelling and analysis of coupling dynamics of swinging a lower limb exoskeleton

Modelling and analysis of coupling dynamics of swinging a lower limb exoskeleton

Coupled Dynamic Analysis of a Bottom-Fixed Elastic Platform with Wave Energy Converters in Random Waves

A Wavestar-type Wave Energy Converter (WEC) on an elastic foundation structure was investigated using an author-developed coupled dynamic analysis computer program. The program included an elastic foundation structure composed of beam elements, a multi-body dynamics model of the entire system, a hydrodynamics model of the dual-buoy, and fully coupled dynamics considering the interaction between the structure and WECs. The selected WEC models a heaving-point-absorber (HPA), one of the oscillating body systems which causes rotational motions of a connecting rod attached to the foundation structure. A rotational-damper-type hydraulic power take-off (PTO) system on the foundation structure produced electricity. The bottom-fixed foundation structure was modeled by three-dimensional beam elements, and the entire system, including HPA, was analyzed by multi-body dynamics. Random wave data at Buan, a nearshore region of Korea, collected by the Korea Meteorological Administration (KMA), was used as a demonstration study using the developed computer programs. Through the case study, the displacement and stress of the foundation structure were increased significantly by the dynamic coupling effects with the WECs, which underscores that the coupled dynamic analysis is essential for a reliable performance evaluation and the design of such a system.

Thermo-electro-mechanical coupling dynamic analysis of piezoelectric structures via stabilized node-based smoothed radial point interpolation method

The thermo-electro-mechanical coupling (TEMC) problem of the piezoelectric structure was analyzed. And the stabilized node-based smoothed radial point interpolation method (SNS-RPIM) was utilized during the computation. And the fundamental formulas were derived under thermo-mechanical load and the model of the problem was analyzed with triangular elements. The existence of thermal stress was taken into consideration. The dynamic behaviors for the TEMC problem were investigated by SNS-RPIM and finite element method (FEM) when different kinds of thermo-mechanical loadings were applied. The superiority of the proposed scheme for the TEMC problems was verified. The empirical constant was set to negative. Besides, the temperature rise can make the model softer and thermal load increase, which leads to a decrease of structural stiffness and natural frequency, thus, the displacement increases.

Modelling and analysis of longitudinal-vertical coupling dynamics for the tracked vehicle on uneven roads

In this paper, a longitudinal-vertical coupling dynamic model of a tracked vehicle under uneven road conditions is established. The torsion suspension forces and torques generated by the torsion bar springs and torsion shock absorbers are considered in the present model. The tracked vehicle’s longitudinal acceleration and velocity change at the same time as the vehicle heaves under the excitation of uneven road terrain. The vehicle’s longitudinal-vertical coupling dynamics are explained elementarily by analysing the longitudinal and vertical dynamics of a road wheel based on the road wheel force model. From the coupling tracked vehicle model, the dynamic responses of the vehicle in the vertical and pitch directions as well as the longitudinal direction are investigated. The vehicle dynamics characteristics are compared with those obtained by Recurdyn simulation. The results indicate that the proposed dynamic model performs well in predicting the dynamic characteristics of the tracked vehicle on uneven roads. By means of the coupling dynamic model, the influences of vehicle speed and road conditions on the vehicle’s longitudinal dynamics are further studied. It has been found that both a higher velocity and a larger roughness coefficient will lead to a negative longitudinal acceleration with larger absolute value.

Coupled dynamic response analysis of multi-column floating offshore wind turbine with low center of gravity

To realize the application of the floating offshore wind turbine (FOWT) from deep to relatively shallow waters, a new concept of multi-column floating wind turbine platform with low center of gravity (CG) is designed and validated. The multi-column low CG platform is designed to support a 6MW wind turbine class and operated at a water depth of 50m in the South China Sea. The frequency domain software WADAM and time domain software NREL-FAST are used to simulate coupled dynamic responses of the floating wind turbine system with second-order wave loads considering. The dynamic behaviors of multi-column low CG FOWT system under normal operation and parked conditions are presented. The influence of second-order wave force on the motion responses of the multi-column platform, fore-aft force and moment of the tower base and mooring force are researched respectively. The results demonstrate that the coupled dynamic responses at rated operating condition and extreme condition meet the normal operating requirements and extreme survival requirements of FOWT system in the shallow water (50m) of South China Sea. In addition, it is found that, the wave frequency response gradually replaces the second-order low frequency response as the main influencing factor of the coupled dynamic response of the FOWT system with the increasing severity of the sea states. However, in general, the magnitude of second-order low frequency response increases with the increasing severity of the design load case. Thus, in the subsequent design of the shallow water FOWT system, the second-order effects should be paid enough attention.

Refined modeling and real-time simulation of grid-connected DFIG

This paper proposes a refined real-time co-simulation platform for Wind Energy Conversion System (WECS). The proposed detailed simulation model considers the aerodynamic, mechanical dynamic, and electromagnetic transients of individual DFIG and electromechanical transients of the power grid. The rotor kinematics equation is used as the interface between the mechanical and electromagnetic models. The Frequency Dependent Network Equivalent (FDNE) method is used to implement the hybrid simulation of electromagnetic and electromechanical transients. The real-time co-simulation platform is built through the combination of FAST developed by NREL, RT-Lab, and PowerFactory. To perform the real-time data interaction between FAST, RT-Lab, and PowerFactory, the communication module is developed based on UDP in this paper. Compared with the existing simulation tools, the proposed co-simulation platform highly enhances the simulation accuracy of WECS. Besides that, the simulation efficiency is also highly improved. The proposed simulation platform can be used for the studies of coupling dynamic analysis, grid-connected dynamic analysis, and hardware-in-the-loop simulation. The DFIG and IEEE 39-bus power grid are used as the case. The case study was conducted and analyzed, proving the correctness and accuracy of the co-simulation platform. Meanwhile, the simulation speed is fast enough for real-time simulation.

Product Multibody Dynamics Analysis for Low-Carbon Footprint

Abstract With the increasingly serious global climate problem, the low-carbon design of products has gradually become an important direction of sustainable manufacturing. The optimization design of product structure is one of the important means to realize the low-carbon operation of product structure. Therefore, how to carry out the low-carbon optimization design of the product is the focus of this paper. In this paper, a new framework of low-carbon manufacturing is constructed, the load on the crane of the offshore wind power installation platform is analyzed, and the dynamic load generated by the crane during lifting, rotating, and luffing is analyzed in detail. The simulation results are compared with the empirical formula provided by the crane design specification and the dynamic analysis results of the crane, which proves the rationality of the simulation results and the dynamic theoretical analysis. And the wind load on the crane is calculated, which provides support for the rigid-flexible coupling dynamic analysis of other parts of the solution. Based on the dynamic simulation and load analysis of the offshore platform crane, the low-carbon optimization design of the offshore platform pile leg is carried out, the carbon emission of the whole life cycle is optimized, and the feasibility of the scheme is verified.

Theoretical and experimental study on vibration reduction and frequency tuning of a new damped-sleeper track

• A new elastic side-supporting long sleeper damping track (ESSDT) is proposed. • A vibration reduction and frequency modulation device (VRFMD) is applied to the ESSDT. • The vehicle-track coupled dynamics analysis is achieved by co-simulation. • The VRFMD can adjust natural frequency and improve dynamics performance of the ESSDT. In urban rail transit, it is important to reduce the train-induced vibration on ambient environment. To achieve this goal, a new elastic side-supporting long sleeper damping track (ESSDT) is proposed in this study. Besides, a novel vibration reduction and frequency modulation device (VRFMD) is also proposed to improve the vibration damping performance as well as structural stability of ESSDT. Based on the vehicle-track coupled dynamics model and the finite element model of ESSDT, dynamic characteristics of ESSDT are investigated theoretically. The influence of key dynamic parameters of VRFMD on the damping effect and stability of the track system are studied in detail. Further, a hammer test was conducted on a full-scale test rig of ESSDT with VRFMD. Test results validate the theoretical research results, which proves that both the vibration of track and the vibration transmitted to the foundation can be attenuated effectively due to the installation of VRFMD. The results show that the spring stiffness of VRFMD has great influence on the dynamic response to ESSDT. The natural frequency of ESSDT could be adjusted by modifying the parameters of VRFMD, which may provide a new approach to avoid wheel-rail contact resonance. Moreover, VRFMD may also be introduced to other types of track for the purpose of vibration reduction and frequency adjustment, such as floating slab track and ladder sleeper track.

Rigid-flexible coupling dynamic modeling and analysis of dumbbell-shaped spacecraft

In this paper, the dynamic modeling of a new configuration spacecraft is investigated. The significance of dumbbell-shaped spacecraft to deep space exploration and the configuration of dumbbell-shaped spacecraft are introduced firstly. Then the dynamic equations of the single flexible body and the kinematic recursive relation between adjacent bodies are deduced. The rigid-flexible coupling dynamic model of the system is established by Jourdain's velocity variation principle and the forward recursive construction formulation for flexible multibody dynamics. The validity of the dynamic model is verified by comparing results with ADAMS. Moreover, the simplification of the dynamic model is investigated to meet the requirements of controller design and the feasibility of conventional simplification method is analyzed. The simulation results show that the conventional simplified model of spacecraft cannot accurately describe the dynamic behaviors of dumbbell-shaped spacecraft. Lastly, a modified attitude dynamic model is proposed and an attitude controller is designed based on this model. The numerical simulations show that the modified model can precisely reflect the dynamic characteristics of dumbbell-shaped spacecraft.

A vertical coupling dynamic analysis method and engineering application of vehicle–track–substructure based on forced vibration

PurposeThis study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track and vehicle caused by local fastener failure.Design/methodology/approachThe track and substructure are decomposed into the rail subsystem and substructure subsystem, in which the rail subsystem is composed of two layers of nodes corresponding to the upper rail and the lower fastener. The rail is treated as a continuous beam with elastic discrete point supports, and spring-damping elements are used to simulate the constraints between rail and fastener. Forced displacement and forced velocity are used to deal with the effect of the substructure on the rail system, while the external load is used to deal with the reverse effect. The fastener failure is simulated with the methods that cancel the forced vibration transmission, namely take no account of the substructure–rail interaction at that position.FindingsThe dynamic characteristics of the infrastructure with local diseases can be accurately calculated by using the proposed method. Local fastener failure will slightly affect the vibration of substructure and carbody, but it will significantly intensify the vibration response between wheel and rail. The maximum vertical displacement and the maximum vertical vibration acceleration of rail is 2.94 times and 2.97 times the normal value, respectively, under the train speed of 350 km·h−1. At the same time, the maximum wheel–rail force and wheel load reduction rate increase by 22.0 and 50.2%, respectively, from the normal value.Originality/valueThis method can better reveal the local vibration conditions of the rail and easily simulate the influence of various defects on the dynamic response of the coupling system.

Dynamic amplification factor of multi-span simply supported beam bridge under traffic flow

Simply supported bridges occupy the majority of bridges. Compared with the flexible large span bridges, Dynamic Amplification Factor (DAF) of them is relatively large and attracts lots of studies. However, most of these studies are focused on the simplified condition that a single vehicle passes through a single span bridge. In general, the bridge bears complex traffic flow rather than a single vehicle. The vehicle type and dynamic loads on the bridge are thus dispersed. It is necessary to explore the multi-vehicle effects on the DAF caused by the complex traffic flow. Also, adjacent spans of a multi-span simply supported beam bridge may have continuous dynamic effects on the vehicles. In this regard, the DAF of a simply supported bridge considering the multi-vehicle and multi-span effects are explored numerically based on the coupling dynamic analysis of traffic flow and bridge, which can also consider the acceleration and deceleration of the vehicles. Cellular Automata (CA) method is used to simulate the traffic flow. It is found that the worse the driving condition of the road roughness, the greater the DAF. When road roughness is Class C, the DAF exceeds the values of American and Chinese codes. Under the action of traffic flow, DAF of the first span of the multi-span simply supported beam is larger than that of the span under the single vehicle. Only considering the effect of a single vehicle may underestimate the dynamic impact on the bridge. Sparse traffic flow has a larger DAF than moderate traffic flow and dense traffic flow in the statistic meaning of the multi-span, because the driving speed of sparse traffic flow is closer to the resonant speed of the bridge and the vibration disharmony of multi-vehicles is smaller. The greater the deceleration of the traffic, the greater the dynamic impact on the bridge.

Titanium alloy piston thermo-mechanical coupling simulation and multi-objective optimization design

To solve the problem between temperature and thermal stress of a titanium alloy piston, a multi-objective optimization method combined response surface methodology and experiment design is performed to calculate an optimal design of the titanium alloy piston. Firstly, the thermo-mechanical coupling analysis, static and dynamic characteristics analysis are carried out. The analysis results show that the thermal load has a significant influence on the piston. Secondly, the five dimensional parameters are chose as the design variables through sensitivity analysis. The piston thermo-mechanical coupling stress, deformation, mass, and the first ring groove are selected as the objective functions. By using the optimal space-filling design method, the sample points between design variables and objective functions are gained. Then, the mathematical relationship between them is obtained by the response surface method. Finally, the multi-objective genetic algorithm is employed to optimize the mathematical model. After optimization, the maximum coupling deformation decreases by 3.05%, the maximum coupling stress decreases by 27.85%, the mass reduces by 5.46%. The maximum temperature of the first ring groove reduces by 12.54%. This study can provide a reference for the piston optimization design.

Unsteady Aeroelastic Coupling Model and Dynamic Response Analysis of Back-swept Blade on Wind Turbines

Unsteady Aeroelastic Coupling Model and Dynamic Response Analysis of Back-swept Blade on Wind Turbines

Волновые движения жидкого топлива в тороидальных сосудах с учетом капиллярного эффекта

A numerical approach is proposed to solve the linear sloshing problem of an incompressible inviscid liquid with account for surface tension effects, which are predominant in the low-gravity environment. A variational formulation is derived by the linearization of motion equations for the liquid near its initial equilibrium state with consideration of a pressure drop on the free surface and a free-end boundary condition on the contact line. The continuous problem domain is discretized by the finite element method. After discretization, the classical generalized eigenvalue problem is obtained, whose solutions are the natural frequencies and mode shapes. Several examples show the effect of the Bond number and the fluid-filled volume on the liquid behavior in toroidal tanks. A comparison of numerical results with experimental measurements under ground conditions reveals that under microgravity condition, the surface tension force and the boundary condition on the contact line play an important role when determining the natural frequencies and mode shapes of the liquid sloshing. Each fluid-filled volume has its own characteristic Bond number, above which the natural frequencies approximate to the experimental values obtained under ground conditions. The presented results can be used in the coupling dynamic analysis of a spacecraft with propellant tanks. The author is grateful to the supervisor associate professor A.N. Tem-nov for help in formulating the problem and discussion of the results of the work.

Coupled Dynamic Analysis of Hybrid Offshore Wind Turbine and Wave Energy Converter

Abstract The combined offshore wind and wave energy on an integrated platform is an economical solution for the offshore energy industry as they share the infrastructure and ocean space. The study presents the dynamic analysis of the Submerged Tension-Leg Platform (STLP) combined with a heaving-type point absorber wave energy converter (WEC). The feasibility study of the hybrid concept is performed using the aero-servo-hydro-elastic simulation tool FAST. The study analyzes the responses of the combined system to understand the influence of the WECs on the STLP platform for various operating conditions of the wind turbine under regular and irregular waves. Positive synergy is observed between the platform and the WECs, and the study also focuses on the forces and moments developed at the interface of the tower and platform to understand the effect of wind energy on the turbine tower and the importance of motion amplitudes on the performance of the combined platform system. The mean and standard deviation for the translation and rotational motions of combined wind and wave energy converters are determined for different sea states under both regular and irregular waves to analyze the change in responses of the structure. The study observed a reduction in motion amplitudes of the hybrid floating system with the addition of the wave energy converters around the STLP floater to improve the energy efficiency of the hybrid system. The study helps in understanding the best possible arrangement of point absorber-type wave energy converters at the conceptual stage of the design process.

Human-exoskeleton coupling dynamics in the swing of lower limb

This paper proposes a new model for the study of lower-limb exoskeletons, which considers both of human and robot’s dynamics with their coupling effects. More specifically, human-exoskeleton interaction is modelled as linear damped springs, with the corresponding coupling coefficients experimentally calibrated by a new experimental platform. In human joint torques, saturation functions are employed to represent loss of wearers’ muscle function, enabling the model applicable for either healthy or unhealthy wearers. This theoretical model is then validated by comparing its responses with the results of an experimental exoskeleton. Thus this validated model is regarded as a solid foundation for the analysis of human-exoskeleton coupling dynamics, based on which we can optimize the control algorithm of exoskeletons, analyse the improvement of human performance, and design comfortable human-exoskeleton interaction.

Rigid–flexible coupling dynamics analysis with joint clearance for a 5-DOF hybrid polishing robot

SUMMARYConsidering the polishing requirements for high-precision aspherical optical mirrors, a hybrid polishing robot composed of a serial–parallel manipulator and a dual rotor grinding system is proposed. Firstly, based on the kinematics of serial components, the equivalent load model for the parallel manipulator is established. Then, the elastodynamic model of kinematic branched-chains of the parallel manipulator is established by using the spatial beam element, and the rigid–flexible coupling dynamic model of the polishing robot is obtained with Kineto-elasto dynamics theory. Further, considering the dynamic properties of the joint clearance, the rigid–flexible coupling dynamic model with the joint clearance for the polishing robot is established. Finally, the equivalent load distribution of the parallel manipulator is analyzed, and the effect of the branched-chain elasticity and joint clearance on the motion error of the polishing robot is studied. This article provides a theoretical basis for improving the motion accuracy and dynamic performance of the hybrid polishing robot.

Dynamic and tribological coupling analysis of journal bearing based on dynamic substructure

Dynamic and tribological coupling analysis of journal bearing based on dynamic substructure

Coupled dynamic analysis of spar-type floating wind turbine under different wind and wave loading

Coupled dynamic analysis of spar-type floating wind turbine under different wind and wave loading