Multibody System Dynamics Research Articles

The Artificial Intelligence and Design of Multibody Systems with Predicted Dynamic Behavior

The problem of complicated dynamic system optimization is very difficult for human intellect. The design of these systems comprises typical tasks of artificial intelligence – big data analysis, decision making, etc. In this article, we applied artificial intelligence approach to optimize the properties of the multibody dynamic system. It is very important to study the whole carrying system of a high-speed railroad in its integrity because the elements of the system interact and influence each other simultaneously. The system should include the train of several cars, the track upper structure, and the bridges. It is possible to synthesize the optimal system with predicted behavior that meets various constraints on dynamic parameters and interaction between the elements of the system.

Research on Low-Frequency Swaying Mechanism of Metro Vehicles Based on Wheel-Rail Relationship

For the worn state of the wheel, metro vehicles often suffer a serious carbody swaying issue, which causes the lateral stability of the vehicle to exceed the limit and affects the ride comfort. An experimental test was carried out on this investigation to study the carbody swaying of the metro vehicle. The field results show that the vehicle system vibrates at around 2.5 Hz in the lateral direction, which leads to the low-frequency swaying on the carbody. In order to explore the formation mechanism of the carbody low-frequency swaying and its relationship with the geometry matching of wheel-rail contact, measured rail and wheel profiles are employed to present a comparative analysis with respect to the initial contact geometry. A multibody dynamic railway vehicle system is established further. Time-domain simulations state that the 2.5 Hz vibration on the carbody belongs to the natural frequency of the vehicle, and the amplitude is larger for the measured wheels than that of the standard wheel profiles. By using the root-locus method, it can be determined that the 2.5 Hz vibration corresponds to the upper swaying mode of the carbody. With the increase in the wheel-rail equivalent conicity, the hunting frequency of bogie increases gradually, which converts frequency with the upper swaying frequency of carbody and leads to carbody low-frequency swaying.

Test technology research and fatigue damage prediction of a car body based on dynamic simulation load spectrum

The dynamic model of a high-speed electric multiple unit (EMU) is established based on the theory of rigid-flexible coupling multi-body system dynamics. Depending on the actual operating conditions of the vehicle, there are a variety of conditions of car body load-time history. We assess ineffective amplitude omission, load spectrum extrapolation, and extreme determination through the car body load-time history, and then obtain the car body fatigue load block spectrum. Finally, we perform a fatigue strength test on the whole car body on a car body fatigue test bench. It is shown that the accelerations of the three directions of the vehicle car body increase with increasing speed. When the train passes a curve, the lateral acceleration average becomes greater. There is also an increase in the car body accelerations in three directions when the train goes through a turnout or twisted line. Under the condition of a failed spring, the vertical acceleration of the car body is obviously increased. Anti-yaw damper failure will cause a significant increase in vehicle lateral acceleration. The failure of lateral and vertical dampers on the second suspension causes an insignificant acceleration increase in three directions. The car body acceleration increases the wear-type profile relative to the original profile in various working and speed level conditions a little. The influence on the damage of vehicle car body under various working conditions is predicted according to the obtained load spectrum.

Dynamic analysis of main transmission mechanism of high-speed cold heading machine based on rigid-flexible coupling model

In the research of high speed cold heading machine, only single part is studied. The interaction between the components of the main drive mechanism is rarely studied. The motion of the main transmission mechanism of the cold heading machine was analysed. The interaction between the components of the main transmission mechanism was studied. This article adopts the theory of multi-body system dynamics. The rigid-flexible coupling model of the main transmission mechanism was established. The dynamics and kinematics simulation of the main transmission mechanism was carried out. The motion curve and stress of the rigid-flexible coupling model are obtained. Compared with the rigid model, the rationality of the rigid flexible coupling model was demonstrated. It provided a reference for further fatigue analysis and optimization of the main transmission mechanism.

Analysis and design of a spacecraft docking system using a deployable boom

Automated spacecraft docking is a technology that has long been pursued. Deep space explorers and small spacecraft can carry fewer resources for docking, such as navigation sensors or latching structures, than can their larger near-Earth counterparts. The concept of the probe–cone docking mechanism is an effective solution to this problem. In this approach, a probe attached to the chaser satellite is guided automatically to the connection part of the target satellite by a conical structure. It is important to have a shock attenuation mechanism at the docking interface to prevent the chaser from being bounced away from the target. In the present paper, an automated docking mechanism that uses a flexible and deployable boom as the probe is proposed, and results of an analysis of the multi-body system dynamics are presented. Although analytical investigations into docking dynamics have been reported, the dynamics depend on many interdependent design parameters, the interaction of which is yet to be investigated. The present work involved a numerical analysis of the effect of each design parameter on the satellite behavior. An energy-based index that can predict the success or failure of docking was also developed in this study. In addition, a design scheme for the parameters is presented based on the results of the analysis in which the optimal combination of the design parameters is determined by searching the solution space.

A DNN-based data-driven modeling employing coarse sample data for real-time flexible multibody dynamics simulations

To achieve real-time simulations for flexible multibody dynamics (FMBD) systems, we suggest data-driven modeling based on deep neural networks (DNNs). While a DNN can represent system dynamics accurately, two main factors of FMBD systems require demanding computational costs for training a DNN. One is a fine discretization of flexible bodies, which produces a large number of training data. The other is the nonlinearity of FMBD, which requires train DNN models to have numerous weight and bias parameters. To overcome these difficulties, we propose a data-driven modeling algorithm for training a DNN efficiently that consists of two steps. First, sets of randomly chosen coarse data sequentially train a DNN model. This helps speed up the training process, even for highly parametrized DNNs. At some point, the model no longer improves, and introducing an error correction step increases the performance of the model. The proposed algorithm is easy to employ and utilizes an efficient size of training data while achieving high performance of the DNN as demonstrated by numerical examples.

A condensed algorithm for adaptive component mode synthesis of viscoelastic flexible multibody dynamics

AbstractA condensed algorithm for adaptive component mode synthesis is proposed to compute the dynamics of viscoelastic flexible multibody systems efficiently and accurately. As studied, the continuous use of modes derived from the initial configuration will lead to poor convergence when dealing with geometric nonlinearity caused by large deformations and overall rotations. The modal reduction at a series of quasi‐static equilibrium configurations should be updated accordingly. According to the loss rate of system energy in the updating process of modal bases, an adaptive mode selection is proposed to reserve the optimal modal bases with their modal number automatically so as to achieve a high‐accuracy simulation. In the proposed condensed iteration algorithm, the order of reduced dynamic equations in the Newton‐Raphson is far less than the number of the unknowns to be discrete in generalized‐α scheme. Using an analytical mapping between the two parts of unknowns, the new algorithm solves a small part of the unknowns iteratively and solves the others noniteratively. Therefore, the saving of time cost comes not only from the proposed adaptive component mode synthesis, but also from the proposed condensed iteration algorithm. The modal bases of subsystems are updated by a series of frame‐like quasi‐static equilibrium configurations independently, in conjunction with the Craig‐Bampton method. Thus, the challenges in the model reduced of extensive ranges of stiffness and damping are removed via the successively updated modal bases. Finally, three numerical tests are made to illuminate the high accuracy and efficiency of the new algorithm proposed.

Mechanical analysis of deepwater drilling riser system based on multibody system dynamics

A multibody system including a drilling riser system, tensioners and a floating platform is key equipment for offshore oil and gas drilling. Most of the previous studies only focus on the drilling riser system rather than the multibody system. Mechanical characteristics of the deepwater drilling riser system cannot be analyzed accurately in a simplified model. Therefore, a three-dimensional multibody analysis program is developed. The static and dynamic characteristics of the deepwater drilling riser system under different platform motions are analyzed based on the developed program. The results show that the static displacement of the riser system with tensioners is smaller than that without tensioners, which means the tensioners can suppress the deformation of the riser system. Under surge and sway motions of the platform, the dynamic displacement of the riser system with tensioners is also smaller than that without tensioners due to the tensioner suppression effect. Besides, the heave motion induces a uniform axial vibration of the riser system, while roll and pitch motions excite the riser system to vibrate laterally. Compared with the stress amplitude due to surge and sway motions, the stress amplitude of the riser system due to heave, roll and pitch motions is relatively small but cannot be neglected.

Dynamics and optimal control of multibody systems using fractional generalized divide-and-conquer algorithm

In this paper, a new framework is presented for the dynamic modeling and control of fully actuated multibody systems with open and/or closed chains as well as disturbance in the position, velocity, acceleration, and control input of each joint. This approach benefits from the computed torque control method and embedded fractional algorithms to control the nonlinear behavior of a multibody system. The fractional Brunovsky canonical form of the tracking error is proposed for a generalized divide-and-conquer algorithm (GDCA) customized for having a shortened memory buffer and faster computational time. The suite of a GDCA is highly efficient. It lends itself easily to the parallel computing framework, that is used for the inverse and forward dynamic formulations. This technique can effectively address the issues corresponding to the inverse dynamics of fully actuated closed-chain systems. Eventually, a new stability criterion is proposed to obtain the optimal torque control using the new fractional Brunovsky canonical form. It is shown that fractional controllers can robustly stabilize the system dynamics with a smaller control effort and a better control performance compared to the traditional integer-order control laws.

A novel nonsmooth approach for flexible multibody systems with contact and friction in 3D space

For computational multibody system dynamics, contact and friction problems are very complex and important problems. Therefore, this paper proposes a novel nonsmooth method for flexible multibody systems with contact and friction in 3D space. Considering the nonsmooth effect of contact and friction on the state variable of the multibody systems, the proposed method is divided into two parts: (i) the change of state variables under the action of smooth force and (ii) the change of state variables caused by contact and friction. Furthermore, for the contact part, the Newton’s impact law and the classical Coulomb friction model are employed to deal with normal impact contact impulse and tangential friction contact impulse, respectively. In addition, Fischer–Burmeister function and Karush–Kuhn–Tucker conditions are also used to solve the normal impact contact impulse and tangential friction contact impulse. What’s more, since the symplectic discrete format performs well robustness to numerical results, the discrete format of the proposed method is based on the symplectic discreteness, and it is expected to obtain the robust numerical results. Finally, several numerical examples are tested by the proposed nonsmooth method, and the numerical simulation results verify the effectiveness of the proposed approach.

A co-simulation method for the analysis of train running performance on a sea-crossing bridge in crosswind environment

When a train crosses a bridge in a crosswind environment, the coupled vibration problem of the train-bridge system becomes prominent, and train safety and riding comfort are difficult to guarantee. Therefore, using the Pingtan Strait bridge in China as a case study, a co-simulation platform for the train-bridge system coupled vibration in crosswind environments was established based on computational fluid dynamics, finite element method, and the multi-body system dynamics. Based on this platform, dynamic response analysis of the train-bridge system was performed at different wind and train speeds. The results indicate that the dynamic response of the train and bridge under double-line conditions is greater than that under single-line conditions. With an increase in wind speed, the mid-span vertical displacement of the bridge changes little, while the lateral displacement increases significantly. Meanwhile, with increasing wind and train speeds, the train dynamic indexes obviously increase. Moreover, the dynamic index of the head car is the largest among all the train sections.

An exact dynamic stiffness method for multibody systems consisting of beams and rigid-bodies

An exact dynamic stiffness method is proposed for the free vibration analysis of multi-body systems consisting of flexible beams and rigid bodies. The theory is sufficiently general in that the rigid bodies can be of any shape or size, but importantly, the theory permits connections of the rigid bodies to any number beams at any arbitrary points and oriented at any arbitrary angles. For beam members, a range of theories including the Bernoulli-Euler and Timoshenko theories are applied. The assembly procedure for the beam and rigid body properties is simplified without resorting to matrix inversion. The difficulty generally encountered in computing the problematic J0 count when applying the Wittrick-Williams algorithm for modal analysis has been overcome. Applications of different beam theories for both axial and bending vibrations have enabled the examination of the role played by rigid-body parameters on the multi-body system's dynamic behaviour. Some exact benchmark results are provided and compared with published results and with finite element solutions. This research provides an exact and highly efficient analysis tool for multibody system dynamics which is for the free vibration analysis, ideally suited for optimization and inverse problems such as modal parameter identification.

A regularization method for solving the redundant problems in multibody dynamic system

Redundant constraints may cause great difficulties during the numerical simulation, when solving the differential algebraic equations (DAEs). The article presents a regularization method based on optimization form of the Gauss principle of least constraint and the Udwadia and Kalaba (UK) method, which expresses the solution of the dynamic motion in an explicit expression. Compared with Lagrange method, the proposed method does not need to solve the Lagrange multipliers any more for the complex multibody mechanical systems. In the end, a numerical example is given to illustrate that the proposed method not only has the ability to handle the problems with redundant constraints, but also has higher accuracy and keep a stable constraint violation level than the traditional methods.

The Effects of Oil Entrained Air on the Dynamic Performance of a Hydraulically Driven Multibody System

In co-simulation, a number of subsystems sharing details of a system, are coupled to exchange data. The subsystem level development of each package enhances the computational efficiency, and more sophisticated packages can be created. However, the data exchange is not always straight forward as different packages can be developed by different research or industrial centers. Therefore, some standards such as Functional Mock-up Interface (FMI) are developed to facilitate the data exchange in co-simulation or co-integration. In this work, the co-simulation approach is employed to investigate the effects of dissolved air on the dynamic performance of a hydraulically driven multibody system. To this end, the subsystems of multibody system dynamics and a hydraulic model are coupled by using the FMU procedure. The utilized FMUs are produced by using an XML model description and a C code for the hydraulic part. The multibody mechanism under investigation is a jib crane model containing three bodies. The model is studied by exciting different sine inputs having known frequencies while varying the amount of dissolved air in the hydraulic system. The results have illustrated that by increasing the amount of entrained air, the pressure amplitude decrease. In addition, the results demonstrated that the amount of the air does not have effects on shifting the system frequency.

Integral dynamics modelling of chain-like space robot based on n-order dual number

In this study, n-order dual numbers were introduced to derive novel dynamics equations of chain-like multi-body deployed on spacecraft. A multi-body system dynamics equation was proposed in the Newton-Euler form, after dual motor, dual mass and dual momentum were provided by establishing operator σ and operation properties. Translation and rotation motion around base are described in the presented integral models based on n-order dual number. Finally, a chain-like space robot manipulator was designed as a verifying example of the n-order dual number scheme applied to multi-body system dynamics. The simulation results showed that the dynamics of each joint was simplified and the coupling effect between the links was reduced.

Hinge joint damage identification method of soft yoke mooring system based on multibody dynamic modeling and structural monitoring data

Soft yoke mooring system (SYMs) is a single-point mooring system used in shallow water oil and gas development. In general, SYMs consists of mooring framework support, mooring legs, yoke, and single-point turret and it forms a multibody dynamic system with 13 hinge joint structures such as universal joints and thrust bearings. The hinge joint is one of the key components of SYMs; therefore, it is necessary to accurately evaluate the operating behavior of the hinge joints. In this study, real-time damage identification is conducted based on the multibody dynamic features of the SYMs. First, a long-term monitoring strategy for the prototype application is developed based on the multibody governing equations of the SYMs. The motion behaviors and stress state of the hinge joints and bodies are calculated using prototype monitoring data. A hinge joint damage identification based on the virtual moment is proposed by considering the changes in the friction coefficient in the damage state. The virtual moment method is used to transform the damage identification problem of the SYMs into a problem of seeking the optimal solution to the dynamics identification function. Genetic algorithm (GA) is implemented to seek the optimal solution of the friction coefficient of each hinge joint. A large-scale model testing system of the SYMs is established to perform the damage identification of the bottom hinge joints of the SYMs. The results show that the proposed method can effectively identify the damage degree and position of the hinge joints of the SYMs and provide a real-time warning system for the in-service operation of the SYMs.

Design and analysis of a scheme for the naval gun test shell entering the bore

The test shell without projectile belt is widely used in the teaching, inspection and maintenance of modern automatic naval guns. In order to ensure the normal work of each mechanism, it is very important to design the buffer and limit of the test shell during the process of entering the bore. Taking a certain type of medium caliber naval gun as the research object, the design of colloidal fluid damper and cartridge lock was proposed to ensure the reliability of entering the bore and closing the breechblock. By combining the simulation methods of computational fluid dynamics (CFD) and multibody system dynamic (MBD), it was analyzed whether the structural design can meet the engineering requirements. The research results show that the colloidal fluid damper can dissipate a large amount of kinetic energy of the shell, and the cartridge lock can limit the rebound movement. The combination of the two ensures the smooth process of closing the breechblock. The research provides a design method for the process of the test shell entering the bore, and provides theoretical support for the feasibility of the method.

Special Issue: Selected Papers From 2019 IDETC-CIE, MSNDC, and VIB Conferences

It is with great pleasure that we bring to the readership of the ASME Journal of Computational and Nonlinear Dynamics (JCND) a special issue dedicated to select papers from the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering (IDETC-CIE) Conferences. The 2019 IDETC-CIE conferences took place in Anaheim, CA, from August 18–21.We started this project motivated by our conviction that organizing a JCND special issue tied to the Multibody Systems and Nonlinear Dynamics and Controls (MSNDC) Conference, as well as the Mechanical Vibration and Noise (VIB) Conference, is long overdue. Last year, we had the 16th and 32nd editions of the MSNDC and VIB conferences, respectively. These two peer-reviewed conferences, whose focus includes vibrations, nonlinear dynamics, and multibody systems, have provided an international venue where our colleagues have presented an early glimpse into their highest-quality research. Following a parallel path, JCND was established in 2005, and under the effective leadership and steady guidance of Professors Subhash C. Sinha, Ahmed Shabana, and Bala Balachandran, this journal has become in short order a premier ASME journal with a current impact factor of 2.135.We happily took this opportunity to act on a project that we believe will help the MSNDC and VIB conferences, the JCND journal, and most importantly, the community at large. Indeed, we hope that through the publication of this special issue, its international readership will be reminded of the ASME IDETC-CIE conferences and their continued impact over the years. Perhaps this special issue will provide extra motivation for scholars to participate yet again, or perhaps for the first time, in this annual gathering of experts, students, and people new to the field. Conversely, the JCND will stand to benefit from bringing to its readership a selection of the best papers presented at the conference. The biggest winner, though, is the community at large. First, anyone who missed the Anaheim event will find in this special issue some of the conference highlights. Moreover, it is only fitting that a group of colleagues who took the time and effort to report on their recent research at the conference receive recognition for their hard and innovative work through this special issue, and it must be great work indeed given that the papers were selected through a rigorous peer selection and review process. The conference paper reviewers recommended a larger collection of manuscripts, which was then trimmed by the symposium organizers, before being down-selected yet again by our four-person group. The remaining manuscripts went through the standard JCND review process. The manuscripts that cleared this last hurdle make up this special issue. We hope you will enjoy them.We are indeed very happy to have had the opportunity to work on this special issue and start what we hope will become an annual tradition. Special thanks to Professor Bala Balachandran for giving us the green light on this idea and to Amy Suski for helping us greatly at every step of the process. It was great working as a team on this project and we are excited to bring it to fruition.

Multibody Dynamics Versus Fluid Dynamics: Two Perspectives on the Dynamics of Granular Flows

Abstract Considering that granular material is second only to water in how often it is handled in practical applications, characterizing its dynamics represents a ubiquitous problem. However, studying the motion of granular material poses stiff computational challenges. The underlying question in this contribution is whether a continuum representation of the granular material, established in the framework of the smoothed particle hydrodynamics (SPH) method, can provide a good proxy for the fully resolved granular dynamics solution. To this end, two approaches described herein were implemented to run on graphics processing unit (GPU) cards to solve the three-dimensional (3D) dynamics of the granular material via two solution methods: a discrete one, and a continuum one. The study concentrates on the case when the granular material is packed but shows fluid-like behavior under large strains. On the one hand, we solve the Newton–Euler equations of motion to fully resolve the motion of the granular system. On the other hand, we solve the Navier–Stokes equations to describe the evolution of the granular material when treated as a homogenized continuum. To demonstrate the similarities and differences between the multibody and fluid dynamics, we consider three representative problems: (i) a compressibility test (highlighting a static case); (ii) the classical dam break problem (highlighting high transients); and (iii) the dam break simulation with an obstacle (highlighting impact). These experiments provide insights into conditions under which one can expect similar macroscale behavior from multibody and fluid dynamics systems governed by manifestly different equations of motion and solved by vastly different numerical solution methods. The models and simulation platform used are publicly available and part of an open source code called Chrono. Timing results are reported to gauge the efficiency gains associated with treating the granular material as a continuum.

Geometrically exact planar Euler-Bernoulli beam and time integration procedure for multibody dynamics

A new formulation of geometrically exact planar Euler-Bernoulli beam in multi-body dynamics is proposed. For many applications, the use of the Euler-Bernoulli model is sufficient and has the advantage of being a nodal displacement-only formulation avoiding the integration of rotational degrees of freedom. In this paper, an energy momentum method is proposed for the nonlinear in-plane dynamics of flexible multi-body systems, including the effects of revolute joints with or without torsional springs. Large rotational angles of the joints are accurately calculated. Several numerical examples demonstrate the accuracy and the capabilities of the new formulation.