bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recursive Formalism With a Minimal Dynamic Parameterization for the Identification and Simulation of Multibody Systems
Authors: Chenut Xavier , Fisette Paul , Samin Jean-Claude 
Published: February 2021

Abstract
This paper proposes a recursive formalism to obtain the equations of motion of multibody systems, using a minimal dynamic parameterization. The use of a minimum set of parameters allows its identification, and the recursivity allows to deal with MBS of any size. A semi-explicit form of the equations for subsequent simulation of the MBS is also introduced.
Firstly, a symbolic recursive Newton-Euler formalism in barycentric parameters for open tree-like structures is established. It can be shown that the barycentric parameters appear linearly in these equations which can thus be easily derived with respect to the parameters, leading to the corresponding identification matrix.
However, in the general case, the barycentric parameters do not form a minimal set of parameters for the MBS. As a consequence, the identification matrix can never be made full rank, whatever the excitation trajectory, preventing us from correctly identifying the parameters. Therefore, a minimal set of parameters is obtained using recursive rules that can be applied systematically to any open MBS. These new parameters are then fed into the Newton-Euler equations which conserve their linearity with respect to them.
Finally, a semi-explicit form of the equations of motion is established, using the minimal parameter set, allowing subsequent simulation of the identified MBS.
As regards the applications, the initial motivation of these developments is lying in the field of biomechanics, where knowledge of the dynamic parameters of the human body is of great importance. Based on motion data and reaction force/torques data, a minimal set of parameters for the human body can be identified. Simulation results will be shown during the oral presentation.
A Poisson-Based Formulation for Frictional Impact Analysis of Open and Closed-Loop Multibody Mechanical Systems
Authors: Lankarani Hamid M. , Ayyagari Murthy 
Published: February 2021

Abstract
Frictional impact analysis requires a friction model capable of correct detection of all possible impact modes such as sliding, sticking, and reverse sliding. Conventional methods for frictional impact analysis have either shown energy gain or not developed for jointed mechanical system, and especially not for closed-chain multibody systems. This paper presents a general formulation for the analysis of impact problems with friction in both open- and closed-loop multibody mechanical systems. The Poisson’s hypothesis is used for the definition of the coefficient of restitution, and thus the energy gains inherent with the use of the Newton’s hypothesis are avoided. A canonical form of the system equations of motion using Cartesian coordinates and Cartesian momenta is utilized. The canonical momentum-balance equations are formulated and solved for the change in the system Cartesian momenta using an extension of Routh’s graphical method for the normal and tangential impulses. The velocity jumps are calculated by balancing the accumulated system momenta during the contact period. The formulation is shown to recognize all modes of impact; i.e., sliding, sticking, and reverse sliding. The impact problems are classified into seven cases, and based on the pre-impact system configuration and velocities, expressions for the normal and tangential impulses are derived for each impact case. Examples including the impact of a falling rod on the ground, the tip of a double pendulum impacting the ground, and the impact of the rear wheel and suspension system of an automobile executing a very stiff bump are analyzed with the developed formulation.
Defining the Coefficient of Restitution for the Impact Between Free and Constrained Bodies
Authors: Escalona J. L. , Mayo J. M. , Domínguez J. 
Published: February 2021

Abstract
This paper revisits the coefficient of restitution involved in the impulse-momentum balance equations for colliding rigid bodies and examines its extension to impacts between flexible bodies. The analytical solution to axial impact on a flexible rod is used to demonstrate that the coefficient of restitution is not inherent in the underlying physical process. In fact, the type of coefficient to be used in each case depends on the particular model employed by the analyst to describe flexibility in the bodies concerned. It is demonstrated that the coefficient of restitution used in the generalized impulse-momentum balance for flexible bodies does not represent a physical magnitude. In any case, as shown in this paper, the ratio between the relative velocities at the contact points or surfaces of the flexible bodies before and after impact is no measure of the local loss of mechanical energy during the process.
Pieced-Interval Modal Response of Elastic Systems With High-Frequency Excitations
Authors: Khulief Y. A. 
Published: February 2021

Abstract
The current technology manifests a great demand for high precision and high positioning accuracy in many engineering applications that range from robot manipulators and high-speed flexible mechanisms to supercritical rotors and the space deployable structures. A reliable dynamic model is crucial to the performance evaluation and precision control of such elastic mechanical systems. The modeling problem becomes even more difficult when higher frequencies of such large scale systems are excited. A pieced-interval modal analysis scheme is introduced to alleviate the problem of handling a system of widespread eignspectrum. A set of energy indices is defined to monitor the energy content in higher modes. The numerical scheme invokes a modal transformation with changeable basis that accounts for higher modes only when they are excited, and picked up more proportional values of the systems total energy. Numerical examples are presented to demonstrate the applicability of the developed method and to display its potential in performing efficient modeling of the dynamic behavior of such systems.
Motion Design by Interference Analysis of Multibody Systems
Authors: Wang Deming , Beale David 
Published: February 2021

Abstract
A new computer aided analysis method for frictionless interference impact problems between two bodies in a constrained multibody system is presented in the paper, which can be used to perform interference analysis and motion design of multibody systems. A virtual contact joint concept is used to detect interference between two bodies and calculate the jump in the body momenta, velocity discontinuities, rebounds and system motion after the interference impact analysis. The interference surfaces can be any geometric element, such as point, line segment, are and circle described by the joint coordinates of the virtual contact joint. The method are very useful to predict and determine the interference time, the types and positions of two impact surfaces. System motion after the interference can be controlled by changing some dynamic parameters in the multibody system.
Development of the Mobile Manipulator Analyzer
Authors: Pitts David T. , Emami M. Reza , Goldenberg Andrew A. 
Published: February 2021

Abstract
This paper presents a simulation package for mobile manipulators that incorporates toolbox software based on commercial dynamic simulation packages, a validation procedure, and an algorithm to tune the system parameters to match the real system. Finally, as an application of the package, an optimization procedure on the design parameters of a commercial robot with results is presented.
Flatness-Based Control of Underconstrained Cable Suspension Manipulators
Authors: Maier Thomas , Woernle Christoph 
Published: February 2021

Abstract
Underconstrained cable suspension manipulators support a load platform in space by less than six spatially arranged cables with independently controllable winches. To control the motion of the platform along desired trajectories in space, the classical inverse kinematic or computed-torque schemes are generalized using the concept of flat systems. For desired trajectories of the load platform and a sufficient number of their time derivatives, the control inputs can be algebraically calculated. Asymptotically stable tracking behaviour is achieved by cascaded feedback of state variables. The application of the method is shown for a planar overhead trolley crane as well as for a novel three-cable suspension manipulator.
A Virtual Body and Joint for Constrained Flexible Multibody Dynamics: A Generalized Recursive Formulation
Authors: Bae D. S. , Han J. M. , Choi J. H. 
Published: February 2021

Abstract
This research extends the generalized recursive formulas for the rigid body dynamics to the flexible body dynamics using the backward difference formula (BDF) and the relative generalized coordinate. When a new force or joint module is added to a general purpose program in the relative coordinate formulations, the modules for the rigid bodies are not reusable for the flexible bodies. Since the flexible body dynamics handles more degrees of freedom than the rigid body dynamics does, implementation of the flexible dynamics module is generally complicated and prone to coding mistakes. In order to overcome the implementation difficulties, a virtual rigid body is introduced at every joint and force reference frames. A virtual flexible body joint is introduced between two body reference frames of the virtual and original bodies. Since the multibody system dynamics are formulated by highly nonlinear algebraic and differential equations and there are many different types of joints, a tremendous amount of computer implementation is required to develop a general purpose dynamic analysis program using the relative coordinate formulation. The implementation burden is relieved by the generalized recursive formulas. The notationally compact velocity transformation method is used to derive the equations of motion in the joint space. The terms in the equations of motion which are related to the transformation matrix are classified into several categories each of which recursive formula is developed. Whenever one category of the terms is encountered, the corresponding recursive formula is invoked. Since computation time in a relative coordinate formulation is approximately proportional to the number of the relative coordinates, computational overhead due to the additional virtual bodies and joints is minor. Meanwhile, implementation convenience is dramatically improved.
Dynamics of Reconfigurable Multibody Systems
Authors: Takahashi Takashi , Matunaga Saburo , Ohkami Yoshiaki 
Published: February 2021

Abstract
Multibody dynamics with configuration changes are characterized by changes in the number and/or kind of constraint equations. Configuration changes mean the addition of impacts, changes of friction states, topological changes and so on. When we consider, for example, the capturing and removing process of the damaged satellites by redundant space robots, such a reconfigurable multibody dynamics must be considered. Dynamics of such a system has not been studied well though it is indispensable to develop the well-functioning automatic machines and robots in space as well as on the earth. We introduced the method to express the time-varying system topologies based on the graph theory and the linked-list, and reformulated the efficient dynamics algorithm based on the “order n algorithm” for forward dynamics of closed-loops systems. In this paper, we explain the above algorithms and how to implement a computer program using the object-oriented programming method. Furthermore, we examine how to apply these programs to space systems.
ODE Methods for Solving the Multibody Dynamics With Constraints
Authors: Koganezawa Koichi , Kaneko Kazuomi 
Published: February 2021

Abstract
This paper deals with methods for solving the multi-body dynamics with constraints. The problem is considered in the framework of solving the Lagrange multipliers in addition to the system coordinates in the differential and algebraic equation (DAE) governing the dynamics with holonomic or non-holonoinic constraints. The proposed methods are originally based on Baumgarte’s work for the holonomic constraints but its extensions. First, one considers a Lagrangian which includes the time-differentiated constraint equations in addition to the constraint equations themselves. Applying the Lagrange procedure we have the ordinary differential equations (ODE), not the DAE, including the differential equation with respect to the Lagrange multipliers. This paper also presents a numerically stable method for inverting the system matrix. The numerical solution for the differential equations with respect to the Lagrange multipliers as well as the system coordinates by using the ordinary numerical integration method, e.g. Runge-Kutta method, shows the excellent stability of the constraints, which is superior to the penalty method.
An Analytical Scheme for Stochastic Dynamic Systems Containing Fractional Derivatives
Authors: Agrawal Om P. 
Published: February 2021

Abstract
This paper presents an analytical technique for the analysis of a stochastic dynamic system whose damping behavior is described by a fractional derivative of order 1/2. In this approach, an eigenvector expansion method proposed by Suarez and Shokooh is used to obtain the response of the system. The properties of Laplace transforms of convolution integrals are used to write a set of general Duhamel integral type expressions. The general response contains two parts, namely zero state and zero input. For a stochastic analysis the input force is treated as a random process with specified mean and correlation functions. An expectation operator is applied on a set of expressions to obtain the stochastic characteristics of the system. Closed form stochastic response expressions are obtained for white noise. Numerical results are presented to show the stochastic response of a fractionally damped system subjected to white noise.
State-Space Based Implicit Integration of the Differential-Algebraic Equations of Multibody Dynamics
Authors: Negrut Dan , Haug Edward J. 
Published: February 2021

Abstract
Three methods for the state-space based implicit integration of differential-algebraic equations of multibody dynamics are summarized and numerically compared. In the state-space approach, the time evolution of a mechanical system is characterized using a number of generalized coordinates equal with the number of degrees of freedom of the system. In this paper these independent generalized coordinates are a subset of the Cartesian position coordinates and orientation Euler parameters of body centroidal reference frames. Depending on the method, the independent generalized coordinates are implicitly integrated and dependent quantities (including Lagrange multipliers) are determined to satisfy constraint equations at position, velocity, and acceleration levels. Five computational algorithms based on the proposed methods are used to simulate the motion of a stiff 14-body vehicle model. Results show that the proposed methods deal effectively with challenges posed by stiff mechanical system simulation. A comparison with a state-space based explicit algorithm for the simulation of the same model indicates a speed-up of approximately two orders of magnitude.
Nonlinear Dynamics of Rigid and Flexible Multibody Systems
Authors: Zakhariev Evtim V. 
Published: February 2021

Abstract
In the present paper a unified numerical approach for dynamics modeling of multibody systems with rigid and flexible bodies is suggested. The dynamic equations are second order ordinary differential equations (without constraints) with respect to a minimal set of generalized coordinates that describe the parameters of gross relative motion of the adjacent bodies and their small elastic deformations. The numerical procedure consists of the following stages: structural decomposition of elastic links into fictitious rigid points and/or bodies connected by joints in which small force dependent relative displacements are achieved; kinematic analysis; deriving explicit form dynamic equations. The algorithm is developed in case of elastic slender beams and finite elements achieving spatial motion with three translations and three rotations of nodes. The beam elements are basic design units in many mechanical devices as space station antennae and manipulators, cranes and etc. doing three dimensional motion which large elastic deflections could not be neglected or linearised. The stiffness coefficients and inertia mass parameters of the fictitious joints and links are calculated using the numerical procedures of the finite element theory. The method is called finite elements in relative coordinates. Its equivalence with the procedures of recently developed finite segment approaches is shown, while in the treatment different results are obtained. The approach is used for solution of some nonlinear static problems and for deriving the explicit configuration space dynamic equations of spatial flexible system using the principle of virtual work and Euler-Lagrange equations.
Parallel Implementation of a New Algorithm for Dynamics of Multibody Systems
Authors: Duan Shanzhong , Anderson Kurt S. 
Published: February 2021

Abstract
In this paper, the new hybrid parallelizable low order algorithm developed by authors is coded in C and MPI, and is implemented numerically on parallel computing systems. To reduce communication overhead, different parallelisms and parallel solution strategies are used for forming and solving equations of motion and constraint equations. The presented implementation can accommodate the general spatial motion of a chain system allowing rotations and translations between neighboring bodies. Different numbers of key joint separations are used to study the influence of increasing dimension of system constraint equations on the overall computational efficiency of the algorithm. Numerical results for implementations of the spatial chain system show that the cutting of certain user-specified joints rather than every joints offers better computational performance. Comparisons between full sequential recursive implementation and parallel implementation of the same algorithm are presented in the form of speedup. Numerical results show that significant speedup can be obtained.
Efficient Dynamic Analysis Method for Multibody Systems With Constraint Violation Stabilization Method
Authors: Reungwetwattana Apiwat , Toyama Shigeki 
Published: February 2021

Abstract
This paper presents an efficient extension of Rosenthal’s order-n algorithm for multibody systems containing closed loops. Closed topological loops are handled by cut joint technique. Violation of the kinematic constraint equations of cut joints is corrected by Baumgarte’s constraint violation stabilization method. A reliable approach for selecting the parameters used in the constraint stabilization method is proposed. Dynamic analysis of a slider crank mechanism is carried out to demonstrate efficiency of the proposed method.
Optimized Realization of Fault-Tolerant Heteropolar Magnetic Bearings for Active Vibration Control
Authors: Na Uhn Joo , Palazzolo Alan 
Published: February 2021

Abstract
The nature of coupling in the heteropolar magnetic bearings permits other remaining active coils in the stator to assume actions of the failed coils to produce the same force resultants. This fault-tolerant control usually reduces load capacity because the redistribution of the magnetic flux which compensates for the failed coils leads to premature saturation in the stator or journal. Distribution matrix of voltages which consists of redefined biasing voltage vector and two control voltage vectors can be optimized in the manner that peak flux density is minimized. An elegant optimization method using Lagrange Multiplier is presented in this paper. The redistribution matrices calculated with Lagrange Multiplier method were compared with Maslen and Meeker’s solutions, local minima are guaranteed and also the global minimum can be obtained if an effective global minimum searching algorithm is used. The linearized control forces can be realized up to certain combination of 5 poles failed for the 8 pole magnetic bearing. Position stiffness and voltage stiffness are calculated for the fault-tolerant magnetic bearings. Simulations show that fault-tolerant control of the multiple poles failed magnetic bearings with a horizontal flexible rotor can be stabilized with reduced load capacity.
High Cycle Fatigue Cracks at Radial Fan Impellers Caused by Aeroelastic Self-Excited Impeller Vibrations: Part I — Case History, Root Cause Analysis, Vibration Measurements
Authors: Eckert Lothar 
Published: February 2021

Abstract
Hydrogen-cooled two-pole turbogenerators are equipped with one single-stage radial fan for cooling gas ventilation. The impellers with outer diameters of up to 1.5 m operate with 3000 rpm or 3600 rpm. High cycle fatigue cracks have occurred at two radial fan impellers operated at 3000 rpm.
An extensive root cause analysis was performed to identify the cause of these cracks. Impeller vibration measurements in the generator unit finally allowed the successful identification of the root cause. The very strong impeller vibrations were caused by an aeroelastic self-excitation mechanism. By modification of the stationary impeller surrounding the aeroelastic self-excitation was eliminated.
Mode Identification for Rotating Rigid Shaft With Flexible Disks by Mode Splits
Authors: Lee Chong-Won , Ham Jong-Seok 
Published: February 2021

Abstract
This paper investigates the mode splits of the bending coupled modes of a rotating shaft with multiple flexible disks, in which the disks are rigidly attached to the rigid shaft supported by bearings. The bending coupled modes, in which shaft bending modes are coupled with one nodal diameter disk modes, are classified as the balanced and unbalanced modes. The mode splits of the balanced modes are the same as those of pure disk modes since the shaft does not experience any motion. On the other hand, the mode splits between pairs of the forward and backward unbalanced modes are found to be dependent upon the disk/shaft configuration and the shaft support stiffness, as well as the rotational speed and the ratio of polar to diametrical moment of inertia.
Optimum Balancing of Three-Dimensional “RSSR” Mechanisms
Authors: Coelho Tarcisio Antonio Hess , Alves Valter Francisco Arruda 
Published: February 2021

Abstract
The Generalized Reduced Gradient method of numerical optimization is applied in obtaining the reduction of moments and forces transmitted to the frame of a three-dimensional RSSR mechanism. Such a modification of dynamic behavior of the mechanism, or balancing, is achieved by the addition of counterweights attached to the moving links in an off-line position. The evaluation of the obtained optimum configuration is performed by comparing the measured vibration levels of the frame of physical models of the balanced and unbalanced mechanism.
Use of the Campbell Diagram in Rotordynamics
Authors: Lalanne Michel , Ferraris Guy 
Published: February 2021

Abstract
This paper deals with bending in the field of monorotors, such as in compressors and turbines, and co-axial multirotors, such as in jet engines. This presentation concerns the use of the Campbell diagram and highlights some specific cases of its use: symmetric systems and highly damped systems.