bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-Stationary Response of Non-Linear SDOF Systems by Perturbation of Wavelet Coefficients
Authors: Chatterjee Pranesh , Basu Biswajit 
Published: November 2020

Abstract
A wavelet based random vibration theory has been developed for the non-stationary seismic response of single degree of freedom (SDOF) systems with cubic type non-linearity in the spring force. The ground motion process has been characterized by statistical functionals of wavelet coefficients. The wavelet transformed coefficient of the displacement response of the oscillator has been perturbed to obtain a series of wavelet domain algebraic equations. The stochastic response of the system has been obtained by using these sets of wavelet domain equations. The root mean square (r.m.s.) displacement response has been obtained in terms of the functionals of the input wavelet coefficients. Parametric variations are carried out to observe the effects of variation of the magnitudes of non-linear spring stiffness on the temporal variation of instantaneous r.m.s. values of oscillator displacements.
Modeling of Track-Wheel-Terrain Interaction for Dynamic Simulation of Tracked Vehicles: Numerical Implementation and Further Results
Authors: Ma Zheng-Dong , Perkins N. C. 
Published: November 2020

Abstract
This paper extends the methods and results of a previous paper (Ma and Perkins, 1999) on simulating track-wheel-terrain interaction for tracked vehicle dynamics. A new solution algorithm is described that includes an adaptive finite element method for remeshing the track model during simulation. Doing so produces a track model that more accurately describes the mechanics of a track as the vehicle negotiates rough terrain. The model and solution algorithm are illustrated using a full vehicle model of an M1A1 tank.
Multibody Systems With Distributed Piezoelectric Actors and Sensors in Flexible Bodies
Authors: Rose Michael , Sachau Delf 
Published: November 2020

Abstract
Efficiency in high speed mechanism can be further increased by use of lightweight construction. But quite often these structures have the drawback of being susceptible to vibrations. This can be overcome by applying the technology of smart structures. Here distributed actuators and sensors made from piezoceramic (PZT) material are capable to actively reduce the unwelcome vibrations if implemented within a control loop. For the optimal design of such kind of mechanism up-to-date simulation tools have to be developed further. To simulate the dynamic behavior of lightweight structures undergoing large motions the multi-body approach is a suitable tool. The necessary parameters in the equations of motion for the flexible body can be calculated from the output of a finite element code. The large number of variables from the finite element model have to be reduced to only a few generalized coordinates. Therefore a modal reduction is applied in combination with the introduction of a moving frame of reference. Beyond this technique so called active modes are introduced to represent the impact of the active strain by the PZT patches. These active modes combined with natural modes represent the body deformation within the multibody model. As an example the slider/crank mechanism with actively controlled PZT patches on the crank is simulated.
A Unified Development of Basis Reduction Methods for Rotor Blades
Authors: Ruzicka Gene C. , Hodges Dewey H. 
Published: November 2020

Abstract
The axial foreshortening effect plays a key role in rotor blade dynamics, but approximating it accurately in reduced basis models has long posed a difficult problem for analysts. Recently, though, several methods have been shown to be effective in obtaining accurate, reduced basis models for rotor blades. These methods are the axial elongation method, the mixed finite element method, and the nonlinear normal mode method. The main objective of this paper is to demonstrate the close relationships among these methods, which are seemingly disparate at first glance. First, the difficulties inherent in obtaining reduced basis models of rotor blades are illustrated by examining the modal reduction accuracy of several blade analysis formulations. It is shown that classical, displacement-based finite elements are ill-suited for rotor blade analysis because they cannot accurately represent the axial strain in modal space, and that this problem may be solved by employing the axial force as a variable in the analysis. It is shown that the mixed finite element method is a convenient means for accomplishing this, and the derivation of a mixed finite element for rotor blade analysis is outlined. A shortcoming of the mixed finite element method is that it increases the number of variables in the analysis. It is demonstrated that this problem may be rectified by solving for the axial displacements in terms of the axial forces and the bending displacements. Effectively, this procedure constitutes a generalization of the widely used axial elongation method to blades of arbitrary topology. The procedure is developed first for a single element, and then extended to an arbitrary assemblage of elements of arbitrary type. Finally, it is shown that the generalized axial elongation method is essentially an approximate solution for an invariant manifold that can be used as the basis for a nonlinear normal mode.
A Proposal of Advanced Modeling for Motion and Vibration in Flexible Structures
Authors: Sagane Takahito , Shono Takashi , Adachi Kazuhito , Kinoshita Takao , Tajima Hiroshi , Seto Kazuto 
Published: November 2020

Abstract
This paper proposes a modeling technique for motion and vibration in flexible structures. We call this technique ‘extended reduced order physical model’. Because vibration is generally influenced by motion, it is necessary to analyze vibration together with motion. New modeling technique can be used to represent both motion and vibration. Effectiveness of this technique is confirmed by characteristics of vibration of a flexible rectangular plate with free support through simulation in this study. Target modes, the first bending and the first torsional modes of the structure reappeared.
A Recursive Implementation Method With Implicit Integrator for Multibody Dynamics
Authors: Cho H. J. , Ryu H. S. , Bae D. S. , Choi J. H. , Ross B. 
Published: November 2020

Abstract
A recursive implementation method for the equations of motion and kinematics is presented. Computational structure of the kinematic and dynamic equations is exploited to systematically implement a dynamic analysis program RecurDyn. A differential algebraic equation solution method with implicit numerical integrators is discussed. Virtual body concept is introduced for the flexible body dynamics. The accuracy of the flexible body solutions is estimated by an error measure and is improved by the dynamic correction mode method. Several examples are solved to demonstrate the efficiency of the proposed methods.
A Method for Constraints Stabilization on Solving Multibody Dynamics
Authors: Koganezawa Koichi , Kaneko Kazuomi 
Published: November 2020

Abstract
This paper deals with methods for solving the multibody 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-holonomic constraints. The proposed methods are originally based on Baumgarte’s work for the holonomic constraints but its extensions to the non-holonomic constraints. Conventionally the Lagrange multipliers are solved algebraically and substituted into the dynamic equations (DAE). This paper, on the other hand, proposes a method to derive the ordinary differential equations with respect to the Lagrange multipliers. One can resort the ordinary numerical integration method to solve the Lagrange multipliers as same as to solve the ODE with respect to the system coordinates. Some examples of numerical solution for the mechanical models having holonomic and non-holonomic constraints shows the excellent stability of the constraints, which is superior to the Baumgarte’s stabilizing method and the penalty method.
The Composite Adaptive Control of Free-Floating Space Robot System With Prismatic Joint
Authors: Chen Li , Liu Yanzhu 
Published: November 2020

Abstract
In this paper, the kinematics and dynamics of a free-floating space robot system with prismatic joint are analyzed, and it is shown that the Jacobian matrix and the dynamic equations of the system cannot be linearly parameterized. With the augmentation approach, we demonstrate that the augmented generalized Jacobi matrix and the dynamic equation of the system can be linearly dependent on inertial parameters. Based on the results, the composite adaptive control scheme for a free-floating space robot with unknown inertial parameters to track the desired trajectory in workspace is proposed, and a two-link planar space robot system with prismatic joint is simulated to verify the proposed control scheme.
Modeling of Joints With Clearance in Flexible Multibody Systems
Authors: Bauchau Olivier A. , Rodriguez Jesus 
Published: November 2020

Abstract
This paper is concerned with the modeling of joints with clearance within the framework of finite element based dynamic analysis of nonlinear, flexible multi-body systems. For actual joints, clearance, lubrication and friction phenomena can significantly affect the dynamic response of the system. In this work, the effects of clearance and lubrication are studied for revolute and spherical joints. The formulation is developed within the framework of energy preserving and decaying time integration schemes that provide unconditional stability for nonlinear, flexible multibody systems. Numerical examples are presented that demonstrate the efficiency and accuracy of the proposed approach. The importance of modeling structural damping and limited driving power are discussed.
A Unified Formulation of Multibody Kinematic Equations in Terms of Absolute, Joint, and Indirect Coordinates
Authors: McPhee John J. 
Published: November 2020

Abstract
This paper reviews some of the coordinate sets employed in multibody dynamic formulations, including absolute, joint, absolute angular, and indirect coordinates. Linear graph theory is then combined with the concept of a “virtual joint” to develop a unified modelling methodology that is capable of representing any of these coordinate sets. An algorithm is proposed and demonstrated for generating the kinematic constraint equations for dependent coordinates, plus kinematic transformations between coordinates (e.g. velocity transformations). The effects of different coordinates on the dynamic equations for a simple manipulator are shown.
Dynamic Finite Element Modeling of Belt-Drives
Authors: Leamy Michael J. , Wasfy Tamer M. 
Published: November 2020

Abstract
In this study, a dynamic finite element model is developed for pulley belt-drive systems. The belt is modeled using truss elements, while the pulleys are modeled using rotating circular constraints, for which the driver pulley’s angular velocity is prescribed. Frictional contact between the pulleys and the belt is modeled using a penalty formulation with frictional contact governed by a Coulomb-like tri-linear friction law. The dynamic response of the drive is then studied by incorporating the model into an explicit finite element code, which can maintain time-accuracy for arbitrarily large rotations and for long simulation times. The finite element solution is validated through comparison to an exact analytical solution of a steadily-rotating, two-pulley drive. Several response quantities are compared, including the normal and tangential (friction) force distributions between the pulleys and the belt, the driven pulley angular velocity, and the belt span tensions. Excellent agreement is found.
Modeling Controlled Articulated Flexible Systems Using Assumed Modes: Part I — Theory
Authors: Mordfin Theodore G. , Tadikonda Sivakumar S. K. 
Published: November 2020

Abstract
Guidelines are sought for generating component body models for use in controlled, articulated, flexible multibody dynamics system simulations. In support of this effort, exact closed-form and numerical solutions are developed for the small elastic motions of a planar, flexible, single link system, in which the link is represented as an Euler-Bernoulli bar in transverse vibration. The link is connected to ground by a pin joint, and the articulation is controlled by proportional and proprotional/derivative (PD) feedback control laws. The characteristics of the closed-form solution are shown to consist of combinations of the characteristic expressions associated with classical end conditions. A large-articulation flexible body model of a controlled-articulation flexible link is then developed and linearized about an arbitrary reference angle. This model uses the method of assumed modes to represent the flexible behavior of the link. It is shown the model is analytically equivalent to a purely structural model which uses a hybrid set of assumed modes, and that numerical convergence can be investigated in terms of admissible functions and quasi-comparison functions. Numerical evaluation of the use of various types of assumed modes is presented in a companion paper.
Realization of Salto Backward Using a Horizontal Bar Exercise Robot
Authors: Takita Yoshihiro , Arai Shigenobu 
Published: November 2020

Abstract
This paper shows a realization of a horizontal bar exercise robot which flies through the air and lands on its feet. This robot has three links that are connected with two rotational joints driven by two DC motors. Each actuator is modeled by a damper and a torsional spring for which the setting angle is able to change during the motion. In order to find the target values of the control, an animation program is developed using the integration of these equations and a trial and error method is used to find them. As a result, an iron bar exercise was simulated by two types of action during the motion. In this paper a self-standing robot is made to realize the rotation around the iron bar and salto backward after the dismount. An experimental result demonstrates a motion that is comparable with the simulated one.
Investigation of the Dynamic Behavior of a Nonlinear Semi-Definite Mechanical System
Authors: Alsaif K. 
Published: November 2020

Abstract
The study reported in this paper investigates the dynamic behavior of a semi-definite nonlinear mechanical structure. It consists of a cantilever beam with uniform thickness subjected to a harmonic excitation at the base; two hinged rigid plates are attached at its free end. The plates can execute oscillations in the horizontal plane without restoring moments. The friction at the hinges is modeled as a Coulomb type with a nonlinear friction coefficient. The excitation parameters at which chaotic motion of the hinged plates is initiated are investigated experimentally as well as numerically. It is shown that the prediction of the dynamic response of this semi-definite system is not accurate in the resonance region. The prediction fails due to the existence of chaotic behavior in that region. The measurement of the dynamic response of the system is conducted using a He-Ne laser system. The numerical results are found to be in a good agreement with the experimental findings.
Nonlinear Effects in Dynamic Analysis of Flexible Multibody Systems
Authors: Samba Y. C. Mbono , Pascal M. 
Published: November 2020

Abstract
The work is concerned with the dynamics of multibody systems with flexible parts undergoing large rigid body motions and small elastic deformations. The standard method used in most cases leads to keep only linear terms with respect to the deformations. However, for large rates or large accelerations, this linearisation is sometimes too premature. In this work, a non dimensional analysis of the system is performed, with some estimate about the order of magnitude of the different parameters occuring in the dynamical model obtained by Kane’s method [1]. A flexible slider crank mechanism is used as a test example, together with AUTOLEV [2] software for numerical results.
Experimental and Analytical Investigation on Spaghetti Problem
Authors: Komaki Yoshimasa , Kobayashi Nobuyuki , Watanabe Masahiro 
Published: November 2020

Abstract
The dynamic behavior of the flexible beam, which is pulled into the slit of the elastic wall with a constant velocity, is discussed with multibody dynamics formulation and experiments. The vibration of the free tip of a flexible beam increases rapidly as pulling into the slit, and this behavior is called “Spaghetti Problem”. The effect of gap size of the slit on the behavior of Spaghetti Problem is especially focused. Dynamic behavior of the beam is simulated numerically and examined the accuracy of the presented formulation by changing the gap size and the pulling velocity of the beam as parameters. It is clarified that the presented modeling method simulates the experimental results quite well, and the gap size and the pulling velocity influence the increase of the lateral vibration near the inlet of the slit.
An Adding Mass Method for Stiffly Mechanical System Simulation and Applications to Construction Machinery
Authors: Imanishi Etsujiro , Yonezawa Satoshi , Sugano Naoki , Hirooka Eiko , Kobayashi Takahiro 
Published: November 2020

Abstract
A characteristic improvement method for dynamic simulation of a stiff mechanical system by adding mass is presented. Hydraulic systems with check valves and control valves on construction machinery exhibit piecewise-linear characteristics for hydraulic flow rate and spool stroke. The proposed improvement method involves no time delay in determining the mass by considering both eigenvalue distortion of the system and time response. This paper shows a practical application to the boom derricking system of a rough terrain crane, and demonstrates that this method is useful for dynamic simulation of hydraulic system including stiff piecewise-linear elements.
An Efficient Finite-Element Modelling Tool for Surgical Simulation: The ε-Mesh Radius
Authors: Azouz Naoufel , Payandeh Shahram 
Published: November 2020

Abstract
This paper presents an algorithm for determining the boundary volume of local mesh for haptic rendering. Here haptic rendering is defined as generation of reaction forces and contact shape information for graphical display. Haptic rendering consists of a number of components: a) scene representation b) scene modelling for global collision detection c) collision detection; d) contact profile and e) scene display. As oppose to classical Finite Element Method or Multi-Body Systems dynamics, haptic rendering deals with the modelling of object where the user can interact with them in the virtual environment. This paper concerns with some aspects related to the interaction between the surgeon tool (probe or micro-robot) and a model of human tissue and organ. Specifically the paper addresses analogies between traditional notion of mesh generation used in finite-element analysis and notion of haptic rendering. In fact, when the user interacts with the object, it is not clear which level of accuracy is needed for the creating the sense of reaction forces at the point of interaction. That is the motivation for proposing the notion of ε-mesh in analogy with the similar notion used in the theory of adaptive meshing. The ε-mesh radius is a scalar quantity defined as a function of the material properties of the contacting bodies, the expected local geometry of the bodies, the direction and relative approach velocities of the bodies. Relationships are presented which show how relative coarseness of the ε-mesh radius with respect to the mesh sizes outside of the radius affect the relative reaction forces.
Lund’s Pad Assembly Method for Tilting Pad Journal Bearings
Authors: Nicholas John C. 
Published: November 2020

Abstract
This paper summarizes the development during the last 50 years of tilting pad journal bearing analysis and design. The major impetus of this development was a landmark paper published by Jorgen Lund in 1964, “Spring and Damping Coefficients for the Tilting-Pad Journal Bearing.” His paper contained the first widely published dynamic coefficients for tilting pad bearings along with his pad assembly method equations.
In the 37 years since Lund’s publication, many other authors have written tilting pad journal bearing codes, the first of which were based on Lund’s assembly method. These assembly method codes were utilized for many years to analyze and design tilting pad bearings for improved rotordynamic performance. During this time, some key design tools were developed utilizing Lund’s method. Other authors have written newer codes which solve the energy and elasticity equations iteratively with the pressure equation, including pad degrees of freedom.
With the simple addition of a turbulence correction and heat balance, many designers continue to utilize Lund’s method, shunning the more modern codes.
Lund’s Elliptic Orbit Forced Response Analysis: The Keystone of Modern Rotating Machinery Analysis
Authors: Kirk R. Gordon 
Published: November 2020

Abstract
A total understanding of rotating machinery vibration analysis requires evaluation of critical speed placement, forced response sensitivity to imbalance, linear onset of instability prediction and full non-linear response analysis. Of these four areas of analysis, only the first three are applied as a basic design tool in modern turbo-machinery analysis. The prediction of multi-mass flexible rotor steady-state elliptic orbit response, including bearing damping and support flexibility, has been and remains in this author’s opinion, to be the basic workhorse and keystone of machinery design. This has now been true for over 35 years. The person responsible for developing this basic method of analysis has been a longtime friend of many engineers worldwide. This paper is written to acknowledge this contribution, one of many in fact, made by Jorgen W. Lund and is presented in memory of his life’s work at this occasion of honoring his contributions to our profession. The utility of the analysis will be discussed and the powerful insight it gives to complex machinery dynamic behavior will be illustrated.
Inertia Effects in Squeeze-Film Damper Bearings Generated by Circumferential Oil Supply Groove
Authors: Lund Jørgen W. , Myllerup Claus M. , Hartmann Henning 
Published: November 2020

Abstract
The dynamic properties of an industrial Squeeze-Film Damper (SFD) bearing design are described using the well-known perturbation approach, where the reaction forces induced by small movements away from the position of equilibrium are expanded into a Taylor series in terms of displacement, velocity, and acceleration. Although generally negligible, the acceleration term can become significant in SFD bearings when inertia effects in the damper lands are enhanced by the flow in a central circumferential oil supply groove. By using a bulk flow approximation in the oil supply groove an explicit expression is derived for the acceleration term. Experimental results confirm the significance of the oil supply groove geometry and appear to validate the bulk flow approximation.