Dynamics of a Radially Rotating Beam With Impact, Part 1: Theoretical and Computational Model

1990 ◽  
Vol 112 (1) ◽  
pp. 65-70 ◽  
Author(s):  
A. S. Yigit ◽  
A. G. Ulsoy ◽  
R. A. Scott
Keyword(s):  
Rigid Body ◽  
Computational Model ◽  
Computational Algorithm ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Body Motion ◽  
Momentum Balance ◽  
Rotating Beam ◽  
Before And After ◽  
Simulation Results

A model is presented for the dynamics of a radially rotating beam with impact. The model uses a momentum balance method and a coefficient of restitution, and enables one to predict the rigid body motion as well as the elastic motion before and after impact. A computational algorithm is also developed to implement the model. In Part 2 simulation results will be compared with experimental results to investigate the validity of the model.

On Planar Impacts of Cylinders and Balls

2019 ◽  
Vol 86 (7) ◽  
Author(s):  
Khalid Alluhydan ◽  
Pouria Razzaghi ◽  
Yildirim Hurmuzlu
Keyword(s):  
Rigid Body ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Discretization Method ◽  
Stiffness Ratio ◽  
Hertz Model ◽  
Local Contact ◽  
Contact Models ◽  
Simulation Results ◽  
Number Of Segments

In this paper, we studied planar collisions of balls and cylinders with an emphasis on the coefficient of restitution (COR). We conducted a set of experiments using three types of materials: steel, wood, and rubber. Then, we estimated the kinematic COR for all collision pairs. We discovered unusual variations among the ball–ball (B–B) and ball–cylinder (B–C) CORs. We proposed a discretization method to investigate the cause of the variations in the COR. Three types of local contact models were used for the simulation: rigid body, bimodal linear, and bimodal Hertz models. Based on simulation results, we discovered that the bimodal Hertz model produced collision outcomes that had the greatest agreement with the experimental results. In addition, our simulations showed that softer materials need to be segmented more than harder ones. Softer materials are materials with smaller collision stiffness values than harder ones. Moreover, we obtained a relationship between the collision stiffness ratio and the number of segments of softer materials to produce physically accurate simulations of B–C CORs. We validated this relationship and the proposed method by conducting two additional sets of experiments.

scholarly journals Dynamics of a Radially Rotating Beam With Impact, Part 2: Experimental and Simulation Results

1990 ◽  
Vol 112 (1) ◽  
pp. 71-77 ◽  
Author(s):  
A. S. Yigit ◽  
A. G. Ulsoy ◽  
R. A. Scott
Keyword(s):  
Computational Model ◽  
Excellent Agreement ◽  
Balance Model ◽  
Momentum Balance ◽  
Rotating Beam ◽  
Elastic Links ◽  
Wide Range ◽  
Sensitivity Studies ◽  
Simulation Results ◽  
Parameter Values

A theoretical and computational model to study the dynamics of a radially rotating beam with impact were presented in Part 1. In this paper the experimental results are presented and they are compared with simulations using the momentum balance model described in Part 1. Excellent agreement was found between the experiments and simulation. Sensitivity studies were employed to show that the model is applicable for a fairly wide range of parameter values. Thus, the momentum balance method has been demonstrated to be capable of accurately predicting the dynamics of systems which consist of rigid and elastic links undergoing impact.

Stresses in compact end closures for cylindrical pressure vessels

1969 ◽  
Vol 4 (1) ◽  
pp. 57-64
Author(s):  
R W T Preater
Keyword(s):  
Cylindrical Shell ◽  
Rigid Body ◽  
Optimum Design ◽  
Cross Section ◽  
Experimental Verification ◽  
Pressure Vessels ◽  
Rigid Body Motion ◽  
Experimental Results ◽  
Body Motion ◽  
Annular Ring

Three different assumptions are made for the behaviour of the junction between the cylindrical shell and the end closure. Comparisons of analytical and experimental results show that the inclusion of a ‘rigid’ annular ring beam at the junction of the cylider and the closure best represents the shell behaviour for a ratio of cylinder mean radius to thickness of 3–7, and enables a prediction of an optimum vessel configuration to be made. Experimental verification of this optimum design confirms the predictions. (The special use of the term ‘rigid’ is taken in this context to refer to a ring beam for which deformations of the cross-section are ignored but rigid body motion is permitted.)

Modeling and Simulation for Trajectory of TV-Guided Projectile

2015 ◽  
Vol 713-715 ◽  
pp. 278-282
Author(s):  
Ming Hou ◽  
Qiang Han ◽  
Han Chang Wang ◽  
Si Min Bi
Keyword(s):  
Rigid Body ◽  
Modeling And Simulation ◽  
Tilt Angle ◽  
Theoretical Basis ◽  
Attack Angle ◽  
Experimental Results ◽  
Simulation Program ◽  
Trajectory Model ◽  
Simulation Results

Through the analysis of the role of the force and moment on TV-guided projectile, the rigid body trajectory model of the projectile is established, and the simulation program of trajectory is developed based on MATLAB. The simulation results are basically consistent with the experimental results, so the trajectory model can reflect the characteristics of the TV-guided projectile. The characteristics of trajectory, velocity, trajectory tilt angle and attack angle are analyzed by simulations that can provide theoretical basis for improving correction precision.

A Critical Study of the Applicability of Rigid-Body Collision Theory

1996 ◽  
Vol 63 (2) ◽  
pp. 307-316 ◽  
Author(s):  
D. Stoianovici ◽  
Y. Hurmuzlu
Keyword(s):  
Rigid Body ◽  
High Speed ◽  
Equations Of Motion ◽  
Coefficient Of Restitution ◽  
Electrical Circuit ◽  
Experimental Results ◽  
Critical Study ◽  
Low Velocity ◽  
Steel Bars ◽  
Body Theory

This article deals with the collision of steel bars with external surfaces. The central issue of the article is the investigation of the fundamental concepts that are used to solve collision problems by using rigid-body theory. We particularly focus on low-velocity impacts of relatively rigid steel bars to test the applicability of these concepts. An experimental analysis was conducted to study the rebound velocities of freely dropped bars on a large external surface. A high-speed video system was used to capture the kinematic data. The number of contacts and the contact time were determined by using an electrical circuit and an oscilloscope. Tests were performed by using six bar lengths and varying the pre-impact inclinations and the velocities of the bars. The experimental results were used to verify the applicability of Coulomb’s law of friction and the invariance of the coefficient of restitution in the class of impacts considered in this study. Then, given the unusual variation the coefficient of restitution as a result of changing pre-impact inclinations, a theoretical model was developed to explain this variation. A discrete model of the bar was used to obtain the equations of motion during impact. Computed and experimental results were compared to establish the accuracy of numerical model. The internal vibrations of the bar and multi impacts between the bar and the surface were found to be two main factors that cause the variation of the coefficient of restitution. Furthermore, a slenderness factor was proposed to identify the subset of collision problems where the coefficient of restitution was invariant to the inclination angle.

An Observer for Rigid Body Motion With Almost Global Finite-Time Convergence

2014 ◽  
Author(s):  
Amit K. Sanyal ◽  
Maziar Izadi ◽  
Jan Bohn
Keyword(s):  
Numerical Simulation ◽  
Rigid Body ◽  
Finite Time ◽  
The Body ◽  
Measurement Noise ◽  
Body Motion ◽  
Nonlinear Observer ◽  
Control Force ◽  
Finite Time Convergence ◽  
Simulation Results

An observer that obtains estimates of the translational and rotational motion states for a rigid body under the influence of known forces and moments is presented. This nonlinear observer exhibits almost global convergence of state estimates in finite time, based on state measurements of the rigid body’s pose and velocities. It assumes a known dynamics model with known resultant force and resultant torque acting on the body, which may include feedback control force and control torque. The observer design based on this model uses the exponential coordinates to describe rigid body pose estimation errors on SE(3), which provides an almost global description of the pose estimate error. Finite-time convergence of state estimates and the observer are shown using a Lyapunov analysis on the nonlinear state space of motion. Numerical simulation results confirm these analytically obtained convergence properties for the case that there is no measurement noise and no uncertainty (noise) in the dynamics. The robustness of this observer to measurement noise in body velocities and additive noise in the force and torque components is also shown through numerical simulation results.

scholarly journals Dynamic Model and Fault Feature Research of Dual-Rotor System with Bearing Pedestal Looseness

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
Nanfei Wang ◽  
Hongzhi Xu ◽  
Dongxiang Jiang
Keyword(s):  
Finite Element ◽  
Rigid Body ◽  
Dynamic Model ◽  
Rigid Motion ◽  
Rotor System ◽  
Experimental Results ◽  
Body Motion ◽  
Combination Frequency ◽  
Recovery Coefficient ◽  
Vibration Displacement

The paper presents a finite element model of dual-rotor system with pedestal looseness stemming from loosened bolts. Dynamic model including bearing pedestal looseness is established based on the dual-rotor test rig. Three-degree-of-freedom (DOF) planar rigid motion of loose bearing pedestal is fully considered and collision recovery coefficient is also introduced in the model. Based on the Timoshenko beam elements, using the finite element method, rigid body kinematics, and the Newmark-βalgorithm for numerical simulation, dynamic characteristics of the inner and outer rotors and the bearing pedestal plane rigid body motion under bearing pedestal looseness condition are studied. Meanwhile, the looseness experiments under two different speed combinations are carried out, and the experimental results are basically the same. The simulation results are compared with the experimental results, indicating that vibration displacement waveforms of loosened rotor have “clipping” phenomenon. When the bearing pedestal looseness fault occurs, the inner and outer rotors vibration spectrum not only contains the difference and sum frequency of the two rotors’ fundamental frequency but also contains2Xand3Xcomponent of rotor with loosened support, and so forth; low frequency spectrum is more, containing dividing component, and so forth; the rotor displacement spectrums also contain fewer combination frequency components, and so forth; when one side of the inner rotor bearing pedestal is loosened, the inner rotor axis trajectory is drawn into similar-ellipse shape.

An Improved H-Converter Circuit Electromagnetic Interference Analysis

2012 ◽  
Vol 569 ◽  
pp. 525-528
Author(s):  
Wei Zhang
Keyword(s):  
Modeling And Simulation ◽  
Electromagnetic Interference ◽  
Electromagnetic Compatibility ◽  
Experimental Results ◽  
Interference Analysis ◽  
Power Switch ◽  
Before And After ◽  
Pulse Peak ◽  
Simulation Results ◽  
The Moment

H-type converter circuit for the power switch on and off the moment will have a great pulse peak, it Will affect the safe use of components and produce large amounts of electromagnetic interference shortcomings，the paper made some changes of the H-type converter circuit. And in Matlab environment for modeling and simulation, changes before and after the two simulation results show that: the pulse peak is effectively suppressed; also inhibit electromagnetic interference, Improved the electromagnetic compatibility of equipment.Simulation and experimental results show that the technique is feasible

Defining the Coefficient of Restitution for the Impact Between Free and Constrained Bodies

1999 ◽  
Author(s):  
J. L. Escalona ◽  
J. M. Mayo ◽  
J. Domínguez
Keyword(s):  
Mechanical Energy ◽  
Coefficient Of Restitution ◽  
Rigid Bodies ◽  
Momentum Balance ◽  
Balance Equations ◽  
Flexible Bodies ◽  
Local Loss ◽  
Contact Points ◽  
Before And After ◽  
The Impact

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.

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