A Multibody System Model for Meshing Gears

2010 ◽  
Vol 44-47 ◽  
pp. 1273-1278 ◽  
Author(s):  
Liu Lei
Keyword(s):  
Multibody Dynamics ◽  
Multibody System ◽  
Gear Wheel ◽  
Numerical Approach ◽  
Computational Effort ◽  
Rigid Bodies ◽  
The Body ◽  
System Model ◽  
New Approach ◽  
Elastic Elements

As a type of numerical approach to dynamics of gears, multibody dynamics method can handle realistic cases of contact modeling with acceptable accuracy and considerably less computational effort. The ability to simulate contact between teeth has become an essential topic in multibody dynamics. Fully rigid method is not suited for a high quality of the analysis to take into account some elasticity in the model of meshing gear wheels. In our new approach the circumferentially rotatable rigid teeth and elastic elements composed of rotational spring-damper combinations are hereby put forward. The teeth and the body of each gear wheel are still regarded as rigid bodies, but they are connected with each other by elastic elements. Besides, Lankarani & Nikravesh Contact Model is utilized, which counts energy dissipation by means of viscous damping. Both large motions with revolutions and important elasticity are considered in this teeth-wheel multibody system model. Two examples are provided in which the simulation results of completely rigid method, the approach in [10], our new approach and finite element methods are compared. Comparisons indicate that our newly developed approach is more suitable for modeling multibody geared systems.

Hydrodynamics and Flow Characterization of Tuna-Inspired Propulsion in Forward Swimming

2019 ◽  
Author(s):  
Junshi Wang ◽  
Huy Tran ◽  
Martha Christino ◽  
Carl White ◽  
Joseph Zhu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Underwater Vehicle ◽  
Numerical Approach ◽  
Primary Objective ◽  
Computational Effort ◽  
The Body ◽  
Hydrodynamic Performance ◽  
Immersed Boundary ◽  
Ring Structures

Abstract A combined experimental and numerical approach is employed to study the hydrodynamic performance and characterize the flow features of thunniform swimming by using a tuna-inspired underwater vehicle in forward swimming. The three-dimensional, time-dependent kinematics of the body-fin system of the underwater vehicle is obtained via a stereo-videographic technique. A high-fidelity computational model is then directly reconstructed based on the experimental data. A sharp-interface immersed-boundary-method (IBM) based incompressible flow solver is employed to compute the flow. The primary objective of the computational effort is to quantify the thrust performance of the model. The body kinematics and hydrodynamic performances are quantified and the dynamics of the vortex wake are analyzed. Results have shown significant leading-edge vortex at the caudal fin and unique vortex ring structures in the wake. The results from this work help to bring insight into understanding the thrust producing mechanism of thunniform swimming and to provide potential suggestions in improving the hydrodynamic performance of swimming underwater vehicles.

Orienting Body Coordinate Frames Using Karhunen-Loe`ve Expansion for More Effective Structural Simplification

2006 ◽  
Author(s):  
Tulga Ersal ◽  
Hosam K. Fathy ◽  
Jeffrey L. Stein
Keyword(s):  
Multibody Dynamics ◽  
Multibody Systems ◽  
Multibody System ◽  
Bond Graph ◽  
The Body ◽  
Coordinate Frames ◽  
Highly Sensitive ◽  
Structural Simplification

Previous work by the authors developed a junction-inactivity-based structural simplification technique for bondgraph models. The technique is highly sensitive to the orientation of the body coordinate frames in multibody systems: improper alignment of body coordinate frames may prohibit a significant simplification. This paper demonstrates how the Karhunen-Loe`ve expansion can be used to automatically detect the existence of and to find the transformation into body coordinate frames that render the bond-graph of a multibody system more conducive to simplification. The conclusion is that the Karhunen-Loe`ve expansion complements well the junction-inactivity-based structural simplification technique when multibody dynamics are involved in the system.

Multibody System Dynamics Simulation of Loads in Main Bearings of Crankshafts

2009 ◽  
Vol 628-629 ◽  
pp. 55-60
Author(s):  
Wen Jie Qin ◽  
D.W. Jia ◽  
Q.Y. Liu
Keyword(s):  
Diesel Engine ◽  
System Dynamics ◽  
Multibody System ◽  
Hydrodynamic Lubrication ◽  
Rigid Bodies ◽  
Multibody System Dynamics ◽  
Dynamics Simulation ◽  
System Model ◽  
Adams Software ◽  
Bearing Loads

In this paper, as for the calculation of loads in main bearings in a crankshaft system, multibody system dynamics is used to simulate the dynamic characteristics of the system composed of flexible and rigid bodies, coupled with hydrodynamic lubrication analysis further. The multibody system model with flexible crankshaft of one V8 diesel engine is built in ADAMS software, in which the bearings are modeled as rigid constrained bearings and hydrodynamic bearings respectively. The resulted loads in main bearings using different models are compared. The results show that the deformation of crankshafts has great effect on the values of loads in main bearings, and the bearing loads in different directions tend to uniformity due to the hydrodynamic lubrication.

A Combined Spin-Flip and IP/EA Approach for Handling Spin and Spatial Degeneracies: Application to Double Exchange Systems

2018 ◽  
Author(s):  
Shannon Houck ◽  
Nicholas Mayhall
Keyword(s):  
Single Molecule ◽  
Double Exchange ◽  
Computational Effort ◽  
Strongly Correlated ◽  
Single Molecule Magnets ◽  
New Approach ◽  
Spin Flip ◽  
Model Hamiltonian ◽  
Simultaneous Existence ◽  
Exchange Parameters

<div>Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip Ionization Potential/Electron Affinity (<i>n</i>SF-IP or <i>n</i>SF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly-correlated N<sub>2</sub><sup>+</sup> as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS-<i>n</i>SF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.</div>

A Combined Spin-Flip and IP/EA Approach for Handling Spin and Spatial Degeneracies: Application to Double Exchange Systems

2018 ◽  
Author(s):  
Shannon Houck ◽  
Nicholas Mayhall
Keyword(s):  
Single Molecule ◽  
Double Exchange ◽  
Computational Effort ◽  
Strongly Correlated ◽  
Single Molecule Magnets ◽  
New Approach ◽  
Spin Flip ◽  
Model Hamiltonian ◽  
Simultaneous Existence ◽  
Exchange Parameters

<div>Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip Ionization Potential/Electron Affinity (<i>n</i>SF-IP or <i>n</i>SF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly-correlated N<sub>2</sub><sup>+</sup> as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS-<i>n</i>SF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.</div>

Simulation and Simulation Software Development of the Braking Process of a Subway Train

2014 ◽  
Vol 556-562 ◽  
pp. 294-301 ◽  
Author(s):  
Long Han ◽  
Chun Tian ◽  
Yan Wang ◽  
Meng Ling Wu ◽  
Zhuo Jun Luo
Keyword(s):  
Computational Effort ◽  
Simulation Software ◽  
System Model ◽  
Brake System ◽  
Railway Vehicle ◽  
Model Parameters ◽  
Modeling Process ◽  
Time Simulation ◽  
Subway Train ◽  
Braking Process

This paper deals with the problem of braking process modeling. A subway train braking process simulation software is built, which composes of a GUI and a underlying model. The underlying model consists of a train model and a brake system model. The train model is simplified and built by assembling subcomponent element models of a railway vehicle. The brake system model is simplified and built based on experimental data in order to reduce computational effort. The GUI of the software can be use to input model parameters, display simulation results, and store simulation data. As a result of the simplifications of the modeling process, the developed software can perform real time simulation.

THE METHOD FOR EVALUATING ADAPTIVE CHANGES IN HUMAN MICROCIRCULATORY-TISSUE SYSTEMS

2020 ◽  
Vol 4 (1) ◽  
pp. 88-99
Author(s):  
A.V. DUNAEV
Keyword(s):  
Middle Finger ◽  
Analysis Data ◽  
The Body ◽  
Tissue Oxygen Saturation ◽  
Doppler Flowmetry ◽  
New Approach ◽  
Adaptive Changes ◽  
Palmar Surface ◽  
Tissue Systems ◽  
The Right

The work is aimed at developing a new approach to assessing adaptive changes in microcirculatory tissue systems when various loads are exerted on the body (sports or physiological stresses), based on the analysis of oscillations in microcirculatory blood flow and tissue oxygen saturation, measured by laser Doppler flowmetry (LDF) and tissue reflectance oximetry (TRO). The study involved eight healthy volunteers aged 21–49 years. Measurements were taken on the palmar surface of the middle finger of the right hand and the medial surface of the lower part of the forearm. The rhythmic oscillations of LDF and TRO were studied using wavelet analysis. Data analysis revealed resonant and synchronized oscillations in the LDF and TRO signals in the myogenic range as an adaptive change as a result of a reaction to physical activity and psychoemotional stress.

Flexible Multibody Dynamics Formulation by Hamilton’s Equations

2010 ◽  
Author(s):  
Martin M. Tong
Keyword(s):  
Multibody Dynamics ◽  
Multibody System ◽  
Mass Matrix ◽  
Equations Of Motion ◽  
Flexible Multibody Dynamics ◽  
Flexible Body ◽  
Flexible Multibody System ◽  
Generalized Coordinates ◽  
Flexible Multibody ◽  
The Matrix

Numerical solution of the dynamics equations of a flexible multibody system as represented by Hamilton’s canonical equations requires that its generalized velocities q˙ be solved from the generalized momenta p. The relation between them is p = J(q)q˙, where J is the system mass matrix and q is the generalized coordinates. This paper presents the dynamics equations for a generic flexible multibody system as represented by p˙ and gives emphasis to a systematic way of constructing the matrix J for solving q˙. The mass matrix is shown to be separable into four submatrices Jrr, Jrf, Jfr and Jff relating the joint momenta and flexible body mementa to the joint coordinate rates and the flexible body deformation coordinate rates. Explicit formulas are given for these submatrices. The equations of motion presented here lend insight to the structure of the flexible multibody dynamics equations. They are also a versatile alternative to the acceleration-based dynamics equations for modeling mechanical systems.

scholarly journals B-Spline Impulse Response Functions of Rigid Bodies for Fluid-Structure Interaction Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
S. Zhou-Bowers ◽  
D. C. Rizos
Keyword(s):  
Impulse Response ◽  
Dynamic Models ◽  
Interaction Analysis ◽  
Fluid Structure Interaction ◽  
Rigid Bodies ◽  
The Body ◽  
Impulse Response Functions ◽  
Fluid Structure ◽  
B Spline ◽  
Structure Interaction

Reduced 3D dynamic fluid-structure interaction (FSI) models are proposed in this paper based on a direct time-domain B-spline boundary element method (BEM). These models are used to simulate the motion of rigid bodies in infinite or semi-infinite fluid media in real, or near real, time. B-spline impulse response function (BIRF) techniques are used within the BEM framework to compute the response of the hydrodynamic system to transient forces. Higher-order spatial and temporal discretization is used in developing the kinematic FSI model of rigid bodies and computing its BIRFs. Hydrodynamic effects on the massless rigid body generated by an arbitrary transient acceleration of the body are computed by a mere superposition of BIRFs. Finally, the dynamic models of rigid bodies including inertia effects are generated by introducing the kinematic interaction model to the governing equation of motion and solve for the response in a time-marching scheme. Verification examples are presented and demonstrate the stability, accuracy, and efficiency of the proposed technique.

Sign in / Sign up

Export Citation Format

Share Document