Multi-body System Dynamics Model Research Articles

Modeling and analysis of planar multibody system with mixed lubricated revolute joint

By coupling the mixed lubrication model of a lubricated revolute clearance joint with the dynamics model of multibody system, this study presents a new methodology for modeling and analysis of planar multibody system with mixed lubricated revolute joints. The lubrication model is solved by the Finite Element Method, while the multibody dynamics equations are established by Lagrange׳s method. The hydrodynamic forces built up by the lubricant fluid are evaluated from the knowledge of the system variables and then included into the equations of motion of the multibody system. In the end, the proposed approach is applied to the piston–connecting rod–crank system in a four-stoke gasoline engine with lubricated clearance joint at the small end of the connecting rod.

Investigation of the dynamic behaviour of an automobile wiper system

A rigid-flexible multi-body system dynamic model of a passenger vehicle windscreen wiper system is established in this study to investigate the systems dynamic behaviour. To simulate the impact forces applied by the blades on the windshield and the pressure force distributions along the wiper blades, the blades are modelled as flexible bodies in consideration of their bend and twist deformations. On the basis of the dynamic analysis results, structure improvement measures, including changing the torsional stiffness of the neck of the blade segment and modifying the positions of the pivot points on the blades, are implemented to reduce the reversal impact and improve the wiping uniformity.

A new numerical method for piston dynamics and lubrication analysis

A numerical model for piston dynamics and lubrication analysis is proposed by coupling the lubrication model of piston skirt–liner system and the dynamics model of multibody system consisting of crank, connecting rod and piston. The lubrication model is solved by the Finite Element Method, while the multibody dynamics equations are established with Lagrange multipliers and constraint Jacobian matrix. The validation of the method is verified through comparing with a well-known existing work. Apart from this, some design parameters of piston skirt were investigated so as to reveal their influence on the slap noise and lubrication performances of the piston.

Study of the Vehicle Controllability and Stability Based on Multi-body System Dynamics

In this paper, the 135 Degree of Freedom multi-body system dynamics model was built by using the software ADAMS/CAR, according to the requests of Chinese standards, and the simulating research about 6 performances of automotive controllability and stability were carried on. Based on the simulating results, some automobile’s performance, such as return-ability, slalom-ability and steering efforts-ability, were excellent, but some other performances, such as steady state cornering ability, steering wheel angle pulse input response ability and steering wheel angle step input response ability, were not satisfied. In order to improve the performance of the automobile, three parameters, i.e. the automotive mass, the load of front axis and the torsion stiffness of rear stabilizer anti-roll bar, were selected as the optimized objects. Within the variety range of the parameters, the multi-body system of the automobile was optimized. Automotive controllability and stability is improved obviously based on the simulating results of the optimized multibody system.

Co-Simulation Study for Fuzzy ESP Control Strategy on Vehicle

ESP can help the road vehicle to improve driving dynamics and prevent accidents which result from loss of control. Based on the theory and account method of Multi-body System Dynamics, the Multi-body System Dynamics model of an A-class car is built by the ADAMS/Car software, which includes steering system, front and rear suspension, braking system, body, and so on. In order to study the handling stability of vehicle with ESP control system, the vehicle yaw rate is set as the controlling aim, to build the fuzzy controller of ESP. The performance evaluation methods of vehicle with ESP are proposed to evaluate the handling stability of vehicle with ESP. The results show that the vehicle with ESP can keep the right path, the yaw rate and the vehicle slip angle is all controlled better. The handling stability of vehicle can be improved.

Sensitivity Analysis of the Elastic Properties of Rail Vehicle Suspensions on Vibration Based on the HXN5 Locomotive Model

The dynamic performance of suspensions plays direct role in vibration control of railway vehicles and also has great impact on the ride comfort and operation stability. For assessment of the influence, a method of sensitivity analysis was performed, in which a Multi-Body System (MBS) dynamic model for the HXN5 locomotive counting for significant DOFs and nonlinearities was developed in SIMPACK platform and validated by real tests. More than tens of dynamic simulations were performed by a variety of damping and stiffness coefficients of the primary and secondary suspensions. By simulation, it is found that the vertical stiffness and damping of the primary suspension have the most sensitive influence. The lateral stiffness of the primary suspension, the longitudinal and lateral stiffness as well as the longitudinal and vertical damper of the secondary suspension possess the least effect on the railway locomotive vibration characteristics. It is also shown parameters of the longitudinal stiffness of the primary suspension, the vertical stiffness and lateral damper of secondary suspensions are of intermediate influence.

Study on the mechanism of the formation of polygon-shaped wheels on subway vehicles

This paper discusses the mechanism responsible for the formation of polygon-shaped wheels; the aim is to solve the problem of their occurrence on subway vehicles. This phenomenon occurs mainly as a result of wheel/rail vertical forces created by the vibration of the wheelset over several complete revolutions of the wheel. In addition, a relationship linking the phase angle between two adjacent vertices, the main vibration frequency and running speed of the polygonal wheel is derived. Then, considering a subway vehicle that is powered by a linear induction motor and applying the multi-body system dynamics model, the main frequency of the wheel/rail vertical force under various running speeds is investigated. Analysis of the speed and main frequency value of a subway vehicle covered in this study revealed that a polygonal wheel with nine vertices can be generated in the speed range 72 to 80 km/h.

Fatigue of shaft flange bolted joints under preload force and dynamic response

The bolted joints are used for flange connections which are subjected to preload forces and dynamic loads. This combination of static and dynamic loads in threaded joints result with complex interaction of high mean stresses, high notch effect, thread flanks contact forces and moments, and contact surfaces slippage which leads to fatigue damage. The Multi-body system dynamic model of shaft was used for assessment of dynamic behavior. Finite element model of shaft flange connection, with detailed thread joints made of heat treatable steel 30CrNiMo8 under preload condition and nonlinear thread flanks contact, was created. The Rainflow cycle counting was used as a cycle count method for describing the load cycle with local stress-strain hysteresis loop. Influences of mean stresses, bolt diameter, and stress gradients were taken into account according to FKM guidelines. The most critical fatigue locations were obtained at thread roots.

Wear analysis of revolute joints with clearance in multibody systems

In this work, the prediction of wear for revolute joint with clearance in multibody systems is investigated using a computational methodology. The contact model in clearance joint is established using a new hybrid nonlinear contact force model and the friction effect is considered by using a modified Coulomb friction model. The dynamics model of multibody system with clearance is established using dynamic segmentation modeling method and the computational process for wear analysis of clearance joint in multibody systems is presented. The main computational process for wear analysis of clearance joint includes two steps, which are dynamics analysis and wear analysis. The dynamics simulation of multibody system with revolute clearance joint is carried out and the contact forces are drawn and used to calculate the wear amount of revolute clearance joint based on the Archard's wear model. Finally, a four-bar multibody mechanical system with revolute clearance joint is used as numerical example application to perform the simulation and show the dynamics responses and wear characteristics of multibody systems with revolute clearance joint. The main results of this work indicate that the contact between the joint elements is wider and more frequent in some specific regions and the wear phenomenon is not regular around the joint surface, which causes the clearance size increase non-regularly after clearance joint wear. This work presents an effective method to predict wear of revolute joint with clearance in multibody systems.

Study on the Dynamics of Laser Gyro Strapdown Inertial Measurement Unit System Based on Transfer Matrix Method for Multibody System

The dynamic test precision of the strapdown inertial measurement unit (SIMU) is the basis of estimating accurate motion of various vehicles such as warships, airplanes, spacecrafts, and missiles. So, it is paid great attention in the above fields to increase the dynamic precision of SIMU by decreasing the vibration of the vehicles acting on the SIMU. In this paper, based on the transfer matrix method for multibody system (MSTMM), the multibody system dynamics model of laser gyro strapdown inertial measurement unit (LGSIMU) is developed; the overall transfer equation of the system is deduced automatically. The computational results show that the frequency response function of the LGSIMU got by the proposed method and Newton-Euler method have good agreements. Further, the vibration reduction performance and the attitude error responses under harmonic and random excitations are analyzed. The proposed method provides a powerful technique for studying dynamics of LGSIMU because of using MSTMM and its following features: without the global dynamics equations of the system, high programming, low order of system matrix, and high computational speed.

Research of High Speed Train Carbody Structure Vibration Behaviors and Structure Fatigue Strength Characteristic Technology

The hybrid simulation method based on Multibody Simulation (MBS) and finite element method (FEM) were proposed here and applied to study the relation between carbody structure vibration behaviors and structure fatigue strength characteristic. The detailed steps include: Firstly, rigid-flexible couple vehicle multibody system dynamic model was created and performed to obtain the load time histories corresponded to the typical load cases. Secondly, the carbody structure stresses was calculated through Finite Element (FE) quasi-static stress method. Finally, with the material fatigue property and some uncertainty factors, carbody fatigue damage distribution and life was calculated and evaluated. And the conclusions can be understood that the mechanism between the full vehicle dynamic property and structure damage distribution. The results are also shown that the hybrid simulation technology could be applied into the carbody structure fatigue design.

Dynamics Optimization for the Valve Train of a Diesel Engine

The parameterized multi-body system dynamics model of the valve train of a diesel engine is built in ADAMS. The spring stiffness, spring force, valve mass and valve stiffness are set as experimental factors, and valve seat force and maximum acceleration are set as responses. Dynamic simulation experiments are carried out using design of experiment (DOE) method, from which the notable factors are obtained. The functions of response surfaces on notable factors are gotten, and then optimization design is implemented based on response surfaces.

Brake judder analysis using a car rigid–flexible coupling model

In order to understand the brake judder of a passenger car, the brake judder test of a passenger car was performed with initial speeds of 90, 120, and 150 km/h, end speed of 20 km/h, and pedal forces of 25, 30, 35, and 40 N on a roller dynamometer in a semi-anechoic chamber. The pressure fluctuation of the brake fluid pipe was presented. The accelerations of the steering wheel were recorded at vertical, lateral, and radial directions respectively, and the frequency analysis of the brake judder was also performed. The frequency response functions of the steering system were measured in order to understand the cause of the brake judder. Meanwhile, the multibody system dynamics model of the test vehicle was created with a flexible body and steering system. The brake torque calculated with the brake fluid pressure of the brake pipe in the brake judder test was exerted on the brake systems. The simulated accelerations of the steering wheel were calculated at three different directions, and the frequency analysis of the brake judder was also presented. The design of experiment was presented in order to reduce the brake judder and improve the comfort of the vehicle. An orthogonal array table was designed with 13 factors and 3 levels. The optimum combination was confirmed. The brake judder was also simulated, and the accelerations of the steering wheel were also calculated. Furthermore, the optimization results were verified by the brake judder test. The verification of the optimization indicates that the optimization results are correct and effective.

Research on Dynamic Characteristic of Planetary Gear Train by Visualization Technology

Based on the multi-body dynamics theory and visualization technology, a planetary gear train system is studied in RecurDyn. The multi-body dynamics model of the 2K-H planetary gear train system is built to do the visual analysis on dynamic characteristic of the planetary gear system severally in the ideal steady-state condition and the random-load condition, than the real-time dynamic contact stress and some other meaningful results of the key components are gained. Compared the related simulation results with that of the theoretical analysis, it is known that two kinds of results are consistent and the simulation analysis on the planetary gear train system is correct and accuracy. From the research above, the new idea and analytical tool are provided for the traditional, static, "redundancy" design method of the gear system, and also the effective technical mean is provided in conceptual design of complex mechanical products to predict the performance, then to reduce the "birth defects" in design stage and also an effective and efficient technical means for engineering applications is offered for optimal design and developing new product on gear train system.

Modelling the fore-and-aft apparent mass of the human body and the transmissibility of seat backrests

A combined lumped-parameter and multi-body system dynamic model of the human body–seat system has been constructed with masses and moments of inertia and with linear translational and rotational springs and dampers. The model was developed in four steps by minimising the sum-of-least-squares error between laboratory measurements and model predictions of the fore-and-aft driving point apparent mass and the fore-and-aft transmissibility of a car backrest. Good agreement was achieved between model predictions and both the median measured driving-point apparent mass and the median measured backrest transmissibility with six subjects. The model was capable of representing the measured apparent masses and predicting the backrest transmissibility with the individual subjects. It was also capable of predicting the backrest transmissibilities of two different car seats. A sensitivity study was conducted and the effects of the model parameters on the peak moduli and corresponding frequencies of the apparent mass and the backrest transmissibility are presented.

Optimum Design of Local Cam Profile of a Valve Train

In this paper, optimization of the local cam profile of a valve train modelled by a parameterized Bezier curve is described. Dynamic responses of the valve train are simulated through its multi-body system dynamics model built using ADAMS software. The kriging method is used to build the surrogate model, which presents the relationship between dynamic responses resulting from the multi-body system dynamics simulation and the parameters of the local Bezier profile. The local cam profile is optimized through a generic algorithm, such that the acceleration peak at the valve open phase is reduced significantly.

An investigation of manual transmission drive rattle

Manual transmission gear rattle is an NVH (noise, vibration, and harshness) concern in the automotive industry. It is induced by repetitive impacts on loose (unselected) gear wheel teeth by their corresponding driving pinions. This phenomenon occurs under various loading conditions and is classified accordingly, including ‘idle rattle’ when the transmission is in neutral and ‘creep and drive rattle’ when the transmission is in a gear with a widely open or a partially open throttle. The phenomenon is also present from drive to coast conditions, referred to as overrun rattle. Engine order fluctuations on the input shaft are considered to be the underlying cause for rattle of loose gears. However, the mechanism of transmission of vibration through lubricated contacts is not fundamentally understood. It is surmised that changes in lubricated contact conditions at different bulk oil temperatures may play a key role and, therefore, offer an opportunity to deal with rattle by a root-cause fundamental solution. This means that a detailed multi-physics approach (including dynamics, vibration, and tribology) is needed. This article provides detailed analytical models of lubricated conjunctions in a multi-body dynamics model of a transaxle seven-speed transmission system under creep rattle conditions. The results show the important role of the regime of lubrication in lightly loaded conjunctions, increasing the propensity to rattle at higher temperatures. It is also revealed that the effect of engine order vibration as an initiating source for rattle becomes significant with reduced hydrodynamic contact stiffness at rising temperatures.

Simulation and Experiment of Multi-body system dynamic Model with Clearance Joint for Ammunition Belt System

Traditional mechanics model for ammunition belt system is usually simplified as a motion in a plane,which has a limita- tion of analysis of the latitudinal motion and cannonball fleeing.The longitudinal and latitudinal mechanical characteristic of the ammunition belt system with helical guider is discussed.A multi-body system dynamic model including clearance joints is obtained for the ammunition belt system.In the spring-damp model,a virtual spring connecting the two contact points is assumed to simulate the impact and contact.The simulation and experiment are finished,which indicates that the above model can well simulate and estimate the mechanical characteristic.

SEMI-ACTIVE CONTROL OF RAILWAY VEHICLE STRUCTURE VIBRATION BASED ON MR DAMPER

Based on the flex-rigid multi-body system dynamics model of railway vehicle, the first vertical bend structure modal and vertical and pitch rigid vibration of carbody which reduce the ride quality are controlled using independent modal space control (IMSC) and optimum control theory. A semi-active control strategy using MR damper is proposed to decease the vibration acceleration of the vehicle on the floor, to improve the ride quality of railway vehicle, and to save the energy consumed. The co-simulation of the full vehicle mechanical and semi-active control system is finished in ADAMS and Mat lab//Simulink~(?) environment. The simulation results show that this semi-active control method according to shyhook damper control model is effective, the first bend structure modal of carbody is restrained and the vehicle running behaviour is improved. This semi-active MR damper used in railway vehicle can be designed.

Non-linear dynamics of flexible multibody systems

In this work we set to examine several important issues pertinent to currently very active research area of the finite element modeling of flexible multibody system dynamics. To that end, we first briefly introduce three different model problems in non-linear dynamics of flexible 3D solid, a rigid body and 3D geometrically exact beam, which covers the vast majority of representative models for the particular components of a multibody system. The finite element semi-discretization for these models is presented along with the time-discretization performed by the mid-point scheme. In extending the proposed methodology to modeling of flexible multibody systems, we also present how to build a systematic representation of any kind of joint connecting two multibody components, a typical case of holonomic contraint, as a linear superposition of elementary constraints. We also indicate by a chosen model of rolling contact, an example of non-holonomic constraint, that the latter can also be included within the proposed framework. An important aspect regarding the reduction of computational cost while retaining the consistency of the model is also addressed in terms of systematic use of the rigid component hypothesis, mass lumping and the appropriate application of the explicit–implicit time-integration scheme to the problem on hand. Several numerical simulations dealing with non-linear dynamics of flexible multibody systems undergoing large overall motion are presented to further illustrate the potential of presented methodology. Closing remarks are given to summarize the recent achievements and point out several directions for future research.