Multi-body Dynamics Simulation Model Research Articles

Deep learning-based fault diagnostic network of high-speed train secondary suspension systems for immunity to track irregularities and wheel wear

Fault detection and isolation of high-speed train suspension systems is of critical importance to guarantee train running safety. Firstly, the existing methods concerning fault detection or isolation of train suspension systems are briefly reviewed and divided into two categories, i.e., model-based and data-driven approaches. The advantages and disadvantages of these two categories of approaches are briefly summarized. Secondly, a 1D convolution network-based fault diagnostic method for high-speed train suspension systems is designed. To improve the robustness of the method, a Gaussian white noise strategy (GWN-strategy) for immunity to track irregularities and an edge sample training strategy (EST-strategy) for immunity to wheel wear are proposed. The whole network is called GWN-EST-1DCNN method. Thirdly, to show the performance of this method, a multibody dynamics simulation model of a high-speed train is built to generate the lateral acceleration of a bogie frame corresponding to different track irregularities, wheel profiles, and secondary suspension faults. The simulated signals are then inputted into the diagnostic network, and the results show the correctness and superiority of the GWN-EST-1DCNN method. Finally, the 1DCNN method is further validated using tracking data of a CRH3 train running on a high-speed railway line.

Simulation and verification analysis of the ride comfort of an in-wheel motor-driven electric vehicle based on a combination of ADAMS and MATLAB

To study the ride comfort of wheel-hub-driven electric vehicles, a simulation and verification method based on a combination of ADAMS and MATLAB modeling is proposed. First, a multibody dynamic simulation model of an in-wheel motor-driven electric vehicle is established using ADAMS/Car. Then, the pavement excitation and electromagnetic force analytical equations are provided based on the specific operating conditions of the vehicle and the in-wheel motor to analyze the impact of the electromagnetic force fluctuation from an unsprung mass increase and motor air gap unevenness on vehicle ride comfort after the introduction of an in-wheel motor. Next, the vibration model and the motion differential equation of the body–wheel dual-mass system of an in-wheel motor-driven electric vehicle are established. The influence of the in-wheel motor on the vibration response index of the dual-mass system is analyzed by using MATLAB/Simulink software. The variation in the vehicle vibration performance index with/without the motor electromagnetic force excitation factor is analyzed and compared with the ADAMS multibody dynamics analysis results. The results show that the method based on a combination of ADAMS and MATLAB modeling can forecast the ride comfort of an in-wheel motor-driven electric vehicle, reducing the cost of physical prototype experiments.

Reliability Evaluation for Cable-Spring Folding Wing Considering Synchronization of Deployable Mechanism

The cable-spring folding wing is a novel type of rigid-flexible coupling structure for missiles, which is composed of several sets of deployable mechanisms, with each composed of a wheel-rope transmission system and a parallel spring driving mechanism. The movement of the cable is initiated by the driving force produced by parallel springs, which directly changes the magnitude and the distribution of the driving force. Therefore, the cable-spring folding wing system has the typical characteristics of strong nonlinearity and motion coupling. In addition, each deployable mechanism shares an identical structure, but the distribution of motion parameters is discrepant due to external loads. Asynchronous movement of the cable-spring folding wing will occur and become a significant issue, which is detrimental to the working performance and could even lead to failure. Focusing on these problems, the multi-body dynamics theoretical model and simulation model of deployable mechanism are established, the kinematic and dynamic characteristics of critical components are studied, and the key factors affecting the deployment performance are investigated. A new reliability method with an angular precision control for deployable mechanism is proposed based on the theoretical model. The effectiveness of the proposed model and method is verified by comparing it with the Monte Carlo method. On this basis, the reliability evaluation for cable-spring folding wing, comprehensively considering deployment performance and synchronization, is carried out.

Experimental and Numerical Study on Ergonomic Evaluation of Automotive Seating Comfort

Automotive car seats play a vital role in providing optimum comfort to the occupants when it comes to vehicle comfort. The objective of this study was to perform an experimental and numerical investigation of the ergonomic evaluation of automotive seating comfort. A questionnaire survey was carried out on car drivers driving two different cars namely Tata Indica and Maruti Swift, to understand the perception of drivers on seating comfort. Posture monitoring techniques using Kinect camera and pressure mapping systems were used to analyze the sitting posture and sitting angle. A multibody dynamics analysis technique was used to evaluate the human body exposed to vehicle vibration. The vertical vibration transmissibility was measured from different body segments using this model. Also, with the help of a multibody dynamics simulation model, the results were compared and validated with existing literature. This study suggests suitable sitting posture and sitting angle derived with the help of multibody dynamics simulation along with the experimental investigation, which would reduce the fatigue of the driver when exposed to prolonged driving.

Railway wheel profile fine-tuning system for profile recommendation

This paper develops a wheel profile fine-tuning system (WPFTS) that comprehensively considers the influence of wheel profile on wheel damage, vehicle stability, vehicle safety, and passenger comfort. WPFTS can recommend one or more optimized wheel profiles according to train operators’ needs, e.g., reducing wheel wear, mitigating the development of wheel out-of-roundness (OOR), improving the shape stability of the wheel profile. Specifically, WPFTS includes four modules: (I) a wheel profile generation module based on the rotary-scaling fine-tuning (RSFT) method; (II) a multi-objective generation module consisting of a rigid multi-body dynamics simulation (MBS) model, an analytical model, and a rigid–flexible MBS model, for generating 11 objectives related to wheel damage, vehicle stability, vehicle safety, and passenger comfort; (III) a weight assignment module consisting of an adaptive weight assignment strategy and a manual weight assignment strategy; and (IV) an optimization module based on radial basis function (RBF) and particle swarm optimization (PSO). Finally, three cases are introduced to show how WPTFS recommends a wheel profile according to train operators’ needs. Among them, a wheel profile with high shape stability, a wheel profile for mitigating the development of wheel OOR, and a wheel profile considering hunting stability and derailment safety are developed, respectively.

Mechanism reliability and sensitivity analysis of landing gear under multiple failure modes

For a certain type of aircraft landing gear retraction-extension mechanism, a multi-body dynamic simulation model is established, and the time-dependent curves of force and angle are obtained. Considering the random uncertainty of friction coefficient, assembly error, and the change of hinge wear under different retraction times, the reliability model is built including three failure modes of landing gear, i.e. blocking failure, positioning failure and accuracy failure. Based on the adaptive Kriging model, the reliability and sensitivity of retraction-extension system under the condition of single failure mode and multiple failure modes in series are analyzed, and the rule of reliability and sensitivity changing with the number of operations is given. The results show that the system failure probability of landing gear mechanism tends to decrease first and then increase when considering the given information of random factors, and the influences of random factors on the failure probability vary with the number of operations. This work provides a viable tool for the reliability analysis and design of landing gear mechanisms.

Research And Analysis Of Three Degree Of Freedom Drivetrain Model For Wind Turbine

According to the characteristics of the drivetrain shaft system of large-scale wind turbines, a three-degree-of-freedom wind turbine drivetrain dynamic model is established using Lagrangian equations and dynamic equations, and the drivetrain torsion mathematical model and multi-mass simplified model are extended to Three-degree-of-freedom multi-body dynamics mathematical model. Using this mathematical model can effectively carry out theoretical analysis on the vibration model of wind power generators, and provide a theoretical reference for the design and simulation of the drivetrain. Taking this three-degree-of-freedom mathematical model as a prototype, a three-degree-of-freedom(3-DOF) rigid-flexible coupling multi-body dynamics simulation model is established in Simpack. Perform frequency domain analysis in the dynamic equilibrium state of the drivetrain model to obtain frequency characteristics such as the natural frequency and energy distribution of the drivetrain. According to the frequency characteristics, the potential resonance frequency is identified, and the dynamic response characteristics of the transmission chain are analyzed to determine the dangerous resonance frequency of the dynamic model.

Reducing wheel wear from the perspective of rail track layout optimization

Wheel wear (W-wear) is one of the most critical issues affecting vehicle-track performances and operating costs. Currently, the works on W-wear behavior and W-wear reduction are mainly based on four aspects: wheel-rail (WR) tribology, WR profile, vehicle structure design and active control of vehicle suspensions. Little attention has been paid to the effects of track layout parameters, such as superelevation, gauge, and cant. To supplement the existing research, this work aims to investigate the relationship between W-wear and track layout parameters and ultimately reduce W-wear through optimizing track layout parameters. The framework consists of a series of steps. Firstly, a multibody dynamics simulation (MBS) model of an Sgnss wagon with 55 degrees of freedom (DOFs) is built. Then, taking a 375-m-radius curve as a case, the influence of track layout parameter (superelevation, gauge, and cant) on W-wear and vehicle derailment safety is investigated based on Kriging surrogate model (KSM). Finally, based on optimized results obtained by KSM and particle swarm optimization (PSO), two optimal regions and three reasonable suggestions concerning the layout of a 375-m-radius curve are given from the perspective of reducing W-wear. This study is promising for the parameter setting of those dedicated lines, on which the train speed is usually fixed, such as metro, light rail, and tram.

Design sensitivity and optimization of powertrain mount system design parameters for rigid body modes and kinetic energy distributions

This study evaluates the influences of the powertrain mount design parameters on the frequencies of powertrain rigid body modes and their kinetic energy distributions (KEDs), which play an important role in the low-frequency vibration of vehicles. A total of 12 design parameters (x, y, z position of mount locations and translational stiffness of the front and rear powertrain mounts) were evaluated in terms of their contributions to the aforementioned metrics. A multi-body dynamics simulation model was used in a 512-run modal analysis by varying the design variables across their common range, and the results were used in design sensitivity analysis. Response surface models for the frequencies of each powertrain rigid body mode and their KEDs were derived and subsequently used in optimization studies. It was shown that front and rear powertrain mount stiffness in y-direction has a strong influence on the frequency of powertrain lateral mode (21.5% and 24.5%, respectively). Front mount location in the x-direction demonstrates a strong influence on the pitch mode (25.7%), while the rear mount stiffness in the z-direction is the most influential on frequency of powertrain vertical mode with 29.1%. The location of the rear powertrain mount in the z-direction has a significant effect on the KED of fore-aft mode with 37.8% sensitivity. NSGA-II genetic algorithm with 100 generations was used for optimization to meet a set of design targets compiled from the literature. For the placement of the frequencies of powertrain rigid body modes with desired KED, design sensitivities, which are derived from a system-level approach, give important design direction to address the complex interactions between powertrain mount locations and stiffness and key metrics of the powertrain mount systems. Knowledge of design sensitivity of design parameters is important in the vehicle design cycle for OEMs to prioritize their design decisions. Finally, the optimization methodology is key to tune the design parameters to meet the conflicting design targets more efficiently.

Real-time Vehicle Pose Measurement Technology based on Multi-sensor Information Fusion

To achieve vehicle unmanned driving, it is necessary to obtain the exact position and posture of the vehicle in real time. To get accuracy position and attitude information, multiple different sensors will be used.However, it’s difficult to deal with the collected information and to integrate the relevant data.This article first introduces the method of obtaining measurement data when using encoder, inertial navigation system and GPS alone.Secondly, using the INS/GPS loose combination system to design a multi-sensor information fusion method.In order to verify the accuracy of the method, a multi-body dynamics simulation model was established and a test bench was built.The simulation and experimental results show that the proposed method can well fuse multi-sensor data and accurately obtain the real-time position and attitude of the vehicle body.

Mechanical Condition Identification and Prediction of Spring Operating Mechanism of High Voltage Circuit Breaker

Spring operation mechanism is widely used in high voltage circuit breakers, and its reliability is related to the ability of the circuit breaker breaking fault current. During the life cycle of spring operating mechanism, stress relaxation, metal fatigue, and any other mechanical defects are easily occurring. And the mechanical performance of the circuit breaker will be influenced by the above defects. Therefore, identifying and predicting the mechanical conditions of the spring operation mechanism can improve the reliability of the circuit breaker. In the present paper, the 252 kV circuit breakers are used as test objects. Firstly, the spring stress relaxation test, the life-cycle test, and the failure simulated test of 252 kV circuit breakers are carried out. Secondly, a multi-body dynamics simulation model of the experimental prototype is established. Thirdly, support vector machine, random forest, and deep neural network are used in the condition identification of the circuit breaker to compare their performances. Then, the prediction model of spring in stress relaxation test is built, however, the model is not suitable for the life-cycle test of repeat close-open operation. Finally, the remaining useful life prediction model is proposed by using Wiener Process.

Stress and stability analysis of slewing motion for crawler crane mounted on flexible ground

The ground deformation causes the increasing of crawler crane side loading, even leads to the boom stress failure or crane tipping failure during slewing motion. This paper established a flexible multibody dynamics simulation model considering the coupling effects of the crane mechanical structure flexibility, ground deformation, and load's dynamic pendulum motion. The model has been verified by analytical model based on Winkler foundation and experimental data. Then the simulation model has been further used to analyze the influence of different foundation modulus, slewing speeds, and lifting heights on the crane boom max stress and the tipping stability. The result offers the slewing speed threshold, which can prevent stress and tipping failures for the crawler crane mounted on flexible ground. The research provides reference for the design and safe operation of crawler cranes.

Comparative study on the friction behaviour of piston/bore interface technologies

Engine crank case designs for passenger car applications are based today on two main material technologies: grey cast iron and an increasing share of aluminium-based concepts. Due to the low wear resistance of aluminium, the latter concepts require a wear protective layer for the cylinder bore surface. Iron-based thermal spray coats are widely used for this purpose. The coating improves the tribological behaviour significantly, as previous studies have shown. Additionally, aluminium-based concepts offer advantages regarding engine weight and thermal management. The aim of the presented work was the discussion of these technological concepts regarding the tribological and sealing properties of the piston/bore interface. The study was carried out based on the AVL FRISC Floating Liner Engine. While the basic engine remained unchanged, the cylinder bore surface was varied. In addition to the floating liner friction measurement, the blow-by and lube oil consumption were also measured. A state-of-the-art multi-body dynamic simulation model complements the experimental study, while both simulation and measurement lead to similar conclusions.

Wear damage of out-of-round wheels in rail wagons under braking

Periodic deviation of the diameter of wheel across its circumference is referred to as the out-of-round (OOR) defect that can cause significant damages to wheel – rail interface, affect the service life of various components of the vehicle/track system and the safety of trains. Under braking, OOR defect may exacerbate these damages; to uncover such exacerbation, a multi-body dynamic simulation model in a fixed coordinate system for wagons containing new/ defect free or OOR wheels subject to braking torques has been formulated and validated using a dataset in the literature. Using the validated model, the effects of the repetition order (single or multiple deviations of diameter) of OOR defect and the severity of application of braking torques to wheel wear has been examined. It has been found that under constant speed, the normal contact force increased with the repetition order. The OOR defect dominated the normal contact force with a dynamic impact force factor of 1.48, whilst the new/ defect free wheels exhibited negligible impact force. It is shown that the effect of OOR defect is significant for wear of wheels under normal braking whist under wheel skid, braking torque dominates wear. Wheel unloading ratio is shown to be a better indicator for the determination of risk to derailment, than the commonly used Nadal's derailment quotient where the wheel contains OOR defect.

Influence analysis of track irregularity on running comfort of Maglev train

Background: In this article, the TR08 car of the Shanghai Magnetic Train Demonstration Line was prototyped and a multi-body dynamics simulation model was established. And based on the low-interference track irregularity power spectrum in Germany, track irregularity data was obtained. Used dynamic simulation software, completed the dynamic simulation analysis of the vehicle-rail model controlled by the proportion-integral-derivative control system PID parameters. It can be concluded that the vibration of trains passing through irregular tracks at different speeds, and evaluated its comfort. The optimal solution for the control of the PID parameters of the train also has been derived.
 Aim: Evaluation of operational comfort and suspension gap control effect of Shanghai Maglev Train Demonstration Line by simulation analysis.
 Materials and methods of the studies: Simulation analysis.
 Results: The vibration acceleration and suspension gap of Shanghai Maglev Train Demonstration Line has been obtained.
 Conclusion: By adjusting the parameters of PID control system, the vibration acceleration of train can be reduced and the ride comfort can be improved.

Multi-objective optimization of vibration characteristics of steering systems based on GA-BP neural networks

Currently, multi-objective optimization of steering systems has seldom been reported, and this paper adopted GA-BPNN algorithm to optimize the top two order frequencies of steering systems. Firstly, this paper established the multi-body dynamics model of the steering system and obtained the random road spectrum of 4 wheels through mathematical model. Results showed that random road spectrums at different wheels were not totally the same and the position and size of peak values were also different. Therefore, the road spectrum of a wheel could not be used to replace the road spectrum of all wheels in multi-body dynamics simulation model. Otherwise, computational results would have a big error. Then, vibration accelerations of the steering wheel at different positions were extracted through the multi-body dynamics model of steering system. Results showed that there were two obvious peak values on the curve of vibration acceleration, and peak frequencies were 48.6 Hz and 65.1 Hz. The finite element model of steering system was established to compute the vibration acceleration, and it was compared with the experimental result. Relative error was controlled within 5 %. It indicated that the finite element model in this paper was reliable. In addition, the computational two order modal frequencies were completely the same with the peak frequencies of vibration acceleration, which proved that the peak values of vibration acceleration were totally caused by the top two order modals. Finally, GA-BPNN algorithm was proposed to optimize the structural thickness of key parts on the steering system, and the optimized result was then compared with that of BPNN and PSO-BPNN. Results showed that the optimization efficiency and result of GA-BPNN were obviously superior to those of other algorithms in the process of optimization and iteration. The optimized parameters were reapplied to the computational model of this paper. Vibration accelerations of the steering system at many positions were extracted to compare with those of the original result. Peak frequencies were significantly improved. In addition, vibration accelerations at most frequency points of the whole frequency band were significantly improved.

Development of dynamic base model of a bogie suspended forwarder

A forwarder is an off-road working machine that is used to transport logs from logging sites to a landing area that is accessible by trucks. Soil damage and operator comfort, especially whole-body vibrations when operating on hard and rough terrain, are crucial issues when developing novel forest machines. Most forwarders on the market are heavy machines with articulated steering and they are equipped with pairs of wheels mounted on bogies. For such bogie machines, only the flexibility and the dynamic dissipation in the tyres contribute to the “chassis damping”. The roll and lateral motions are the most severe components of the whole-body vibrations. So, developing new traction units, chassis suspensions and/or cabin suspension are in focus. Model-based design relies on focused models that are as simple as possible, but not too simple. This paper presents a 12 degrees-of-freedom multi-body dynamics simulation model of a standard eight-wheeled bogie type of medium-sized forwarder. The presented model is targeted for assessing and comparing different design solutions. It is shown that a configuration of seven rigid subsystems and eight flexible tyres represented with the simple and computer efficient Fiala tyre model enables the forwarder dynamic simulation model to be used to predict the roll and lateral motions of a forwarder operating on hard and rough terrain.

Design and simulation of a cable-pulley-based transmission for artificial ankle joints

In this paper, a mechanical transmission based on cable pulley is proposed for human-like actuation in the artificial ankle joints of human-scale. The anatomy articular characteristics of the human ankle is discussed for proper biomimetic inspiration in designing an accurate, efficient, and robust motion control of artificial ankle joint devices. The design procedure is presented through the inclusion of conceptual considerations and design details for an interactive solution of the transmission system. A mechanical design is elaborated for the ankle joint angular with pitch motion. A multi-body dynamic simulation model is elaborated accordingly and evaluated numerically in the ADAMS environment. Results of the numerical simulations are discussed to evaluate the dynamic performance of the proposed design solution and to investigate the feasibility of the proposed design in future applications for humanoid robots.

Simulation Study of AC Contactor Dynamic Contacts Contact Pressure Based on ADAMS

A multi-body dynamics simulation model of CJ20-25 AC contactor was established with Pro/E �ƒ Pro/Engineer)in this paper. A coupling simulation with machine, electric, magnetic on the contactor has been achieved in this model. Dynamic parameters which were called use the secondary development technology of ADAMS. The dynamic contact pressure signal of an AC contactor was obtained with ADAMS's own simultane- ous solution such as electromagnetic suction, kinematics and dynamics equations. The simulation results and actual measurement of contactor contact pressure signals are very similar. However, the complexity of the meas- ured contacts vibration is greater than the simulation results because the actual working condition is more com- plex. This result provides a theoretical foundation to the dynamic contacts contact pressure test.

Flexible Multibody Dynamics Modeling and Simulation Analysis of Large-scale Wind Turbine Drivetrain

In order to prevent resonance dangerous and damage in the operation process of large wind turbines, a time / frequency domain integrated resonance screening method is presented. A flexible multibody dynamics simulation model of MW grade wind turbine drivetrain according to the "Guideline for the Certification of Wind Turbines Edition 2010" is established. Three levels of complexity modeling program are comprised and determined optimum modeling program according to the frequency coverage. Accurate flexible multibody dynamics model of drivetrain is achieved by flexible components, bearing stiffness and mesh flexibility, by which Campbell diagram, energy distribution diagram and fast Fourier transform(FFT) diagram are drawn and analyzed for dangerous resonance screening. Theoretical calculations and third-party software are applied for model validation. The results show that the flexible multibody modeling program can describe the dynamics characteristics of complex systems more deeply and comprehensively, avoid frequency limit caused by simplified simulation model, there are dangerous resonance points on natural frequency 9.86 Hz and 206.27 Hz, response components are gearbox housing and stage 2 wheel gear shaft and worthy of attention, the simulation calculation results are in agreement with the theoretical results and third-party software calculation results.