On the Implementation of Coulomb Friction in a Volumetric-Based Model for Contact Dynamics

2007 ◽  
Author(s):  
Yves Gonthier ◽  
John McPhee ◽  
Christian Lange
Keyword(s):  
Coulomb Friction ◽  
General Purpose ◽  
Friction Torque ◽  
Contact Dynamics ◽  
Contact Model ◽  
Elastic Behavior ◽  
Published Data ◽  
Winkler Elastic Foundation ◽  
Tippe Top ◽  
Object Shapes

A contact model based on volumetric properties is presented. The model properties are derived assuming the elastic behavior of the contacting objects can be approximated as a modified Winkler elastic foundation model, and that the contact surface between the objects is approximately flat. The resulting model includes friction and features a contact force proportional to the inter-penetration volume. The work shows that the Coulomb friction is affected by the relative motion. The contact model can be used as a general-purpose tool to model contact dynamics for a broad range of object shapes because the volumetric quantities that serve as input to the contact model can be determined for any object shape. A numerical simulation of a Tippe-Top is presented, and the results are shown to be consistent with published data, but with a higher spinning friction torque.

A Set-Valued Force Law for Spatial Coulomb-Contensou Friction

2003 ◽  
Author(s):  
Remco I. Leine ◽  
Christoph Glocker
Keyword(s):  
Coulomb Friction ◽  
Augmented Lagrangian ◽  
Rigid Bodies ◽  
Friction Torque ◽  
Sliding Velocity ◽  
Time Stepping ◽  
Extended Contact ◽  
Tippe Top ◽  
Augmented Lagrangian Approach ◽  
Pseudo Potential

The aim of this paper is to develop a contact law for combined spatial Coulomb friction and normal friction torque (drilling friction) as a function of sliding velocity and spin. We will call this extended contact law the Coulomb-Contensou friction law and derive it from a non-smooth velocity pseudo potential. A Runge-Kutta time-stepping method is briefly presented for the numerical simulation of rigid bodies with Coulomb-Contensou friction. The algebraic inclusion describing the contact problem is solved with an Augmented Lagrangian approach. The theory and numerical methods are applied to the Tippe-Top, which illustrates the importance of Coulomb-Contensou friction for the dynamics of systems with friction.

scholarly journals Modelling of a Microslip Friction Damper Subjected to Translation and Rotation

1999 ◽  
Author(s):  
Gabor Csaba
Keyword(s):  
Surface Roughness ◽  
Degrees Of Freedom ◽  
Forced Response ◽  
Least Square ◽  
Contact Model ◽  
Contact Radius ◽  
Algebraic Equations ◽  
Friction Damper ◽  
Six Degrees Of Freedom ◽  
Winkler Elastic Foundation

This paper presents a friction interface model where one of the mating surfaces is curved. The model is based on a discretization of the Winkler elastic foundation model and is general in the sense that it allows for relative motion in all six degrees of freedom. The variables for the contact model are based on damper geometry and material data, except coefficient of friction and tangential stiffness coefficient, which have to be measured. Simulated and experimental hysteresis curves are presented. A model of a curved wedge damper has been developed using the contact model. An algorithm for solving forces and displacement when the damper is allowed to move in all six degrees of freedom has been presented. The governing algebraic equations are solved using a nonlinear least-square method routine in a commercial software package. Forced response of a beam-damper-beam test set-up has been simulated and compared with experiments. The results highlighted some effects which have not been modelled e.g. the actual contact area between damper and blade is influenced by surface roughness for low normal loads. It is assumed that this effect resulted in problems in getting agreement between experiments and analysis. The influence of surface roughness is assumed to be negligible when vibrations of real turbomachinery are considered. This is due to the fact that both normal and excitation force on the clamper are about ten times higher than what was used in the experiments and simulations in this paper. Variation of contact radius of the damper shows that a larger radius e.g. a flatter contact gives better damping and increases the resonance frequency. The disadvantage is that the alignment of the damper becomes more unreliable.

Elastic characteristics of the lung perivascular interstitial space

1983 ◽  
Vol 54 (6) ◽  
pp. 1717-1725 ◽  
Author(s):  
J. C. Smith ◽  
W. Mitzner
Keyword(s):  
Elastic Properties ◽  
Lung Volume ◽  
Interstitial Space ◽  
Elastic Behavior ◽  
Published Data ◽  
Fluid Accumulation ◽  
Recoil Pressure ◽  
Vascular Walls ◽  
Isolated Lung ◽  
Volume History

An analysis of the elastic behavior of the lung perivascular interstitial space during interstitial fluid accumulation is presented. Fluid accumulation must deform the lung parenchyma and vascular walls that form the interstitial space boundaries. The deformations of these boundaries are predicted from previously published data on the elastic properties of the boundary materials. The analysis gives the relationships among the elastic properties of the boundaries, the compliance of the interstitium, the lung volume, and the lung elastic recoil pressure. Values of the interstitial compliance are predicted to decrease with increasing lung recoil pressure and are dependent on the lung pressure-volume history. At low recoil pressures over 70% of the interstitial compliance results from deformation of the parenchyma. As the recoil pressure increases, either with increasing lung volume or due to the lung pressure-volume history, the contributions of the parenchymal and vascular wall deformations become similar. The predictions are generally consistent with published data on interstitial compliance obtained from measurements of isolated lung weight gain during vascular fluid transudation. This correlation suggests that the elastic behavior of the interstitial space can be accounted for by the known elastic properties of the boundary materials.

Modeling Contact Dynamics of Vanes With Adjustable Upstream Flow Angles

2012 ◽  
Author(s):  
Daniel Schurzig ◽  
Sebastian Tatzko ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Coulomb Friction ◽  
Nonlinear Behavior ◽  
Simulation Method ◽  
Forced Response ◽  
Contact Forces ◽  
Contact Dynamics ◽  
Flow Angle ◽  
Complementarity Conditions ◽  
Time Stepping ◽  
Upstream Flow

In this paper, a simulation method is proposed for a sub-category of compressor vanes showing nonlinear behavior due to an adjustable upstream flow angle. The proposed algorithm computes the forced response of a single vane based on the New-mark time stepping scheme after reducing the structural matrices using the Craig-Bampton method. The contacts are modeled by Coulomb friction and Newton impact constraints. Contact forces are determined using linear complementarity conditions with decoupled orthogonal friction force directions. Different discretization methods for the cylindrical contact partners are proposed. Finally, numerical results are shown in order to validate the proposed algorithms.

A Compliant Contact Model Including Interference Geometry for Polyhedral Objects

2005 ◽  
Vol 1 (2) ◽  
pp. 150-159 ◽  
Author(s):  
Lianzhen Luo ◽  
Meyer Nahon
Keyword(s):  
Material Properties ◽  
Geometric Parameters ◽  
Contact Dynamics ◽  
Space Robotics ◽  
Dynamics Model ◽  
Geometric Algorithm ◽  
Design Cycle ◽  
Polyhedral Objects ◽  
Simulation Results ◽  
Object Shapes

Modeling of contact with the environment is an essential capability for the simulation of space robotics system, which includes tasks such as berthing and docking. The effect of interbody contact on the robotic system has to be determined to predict potential problems in the design cycle. A compliant contact dynamics model is proposed here that considers most possible contact situations for a wide diversity of possible object shapes and using interference geometry information. A uniform formula is provided to determine the contact force as a function of geometric parameters and material properties. A corresponding geometric algorithm is provided in order to obtain the necessary geometric parameters. Some simulation results are presented based on the implementation of the geometric algorithm.

scholarly journals FULL-FLEDGED SEMANTIC ANALYSIS AS A TOOL FOR RESOLVING TRIANGLE-COPA SOCIAL SCENARIOS

2020 ◽  
Author(s):  
I. M. Boguslavsky ◽  
◽  
V. G. Dikonov ◽  
T. I. Frolova ◽  
L. L. Iomdin ◽  
...  
Keyword(s):  
Common Sense ◽  
Semantic Analysis ◽  
Multiple Choice ◽  
General Purpose ◽  
Published Data ◽  
Data Set ◽  
Text Interpretation ◽  
Common Sense Reasoning ◽  
Two Alternatives ◽  
Common Sense Knowledge

Text interpretation often requires common sense knowledge and reasoning. A convenient tool for developing methods of common sense reasoning are special sets of challenge problems whose interpretation requires sophisticated reasoning. An interesting example is a recently published data set called Triangle Choice of Plausible Alternatives (Triangle-COPA), which contains 100 multiple-choice problems that test the interpretation of social scenarios. Each problem includes a statement and two alternatives. The task is to identify the more plausible alternative. For processing Triangle-COPA data we use SemETAP, a general purpose semantic analyzer. We implement the full scenario of NL understanding starting from NL texts and not from manually composed simplified logical formulas, which is a common practice in logic-based approaches to common sense reasoning. We produce Enhanced Semantic Structures of the statement and both alternatives and check which alternative manifests more semantic agreement with the statement in terms of inferences.

A Simplified Model of the Base-Excited Coulomb Friction Oscillator With Contact Compliance and Inertia

Volume 1 ◽  
2004 ◽  
Author(s):  
Jin-Wei Liang
Keyword(s):  
Approximate Model ◽  
Contact Dynamics ◽  
Contact Model ◽  
Order System ◽  
Stick Slip ◽  
Sliding Motion ◽  
Contact Compliance ◽  
Friction Oscillator ◽  
Rigid Contact ◽  
Two Degree Of Freedom

This work investigates a base-excited Coulomb oscillator with contact compliance and inertia. The full-order system is a two degree-of-freedom (DOF) problem. The study first shows that two existing approximate models, including the rigid-contact model (RCM) and the compliant-contact model (CCM) cannot closely capture the dynamical characteristics of the global pure-sliding responses of the full-order system (FOS). To complement for this, this study proposes a new approximate model denoted as the reduced-order system (ROS), which is especially suitable for studying the contact dynamics subjected to the global pure-sliding motion. Numerical results show that the ROS not only has the merit of simplicity can also reliably depict the global pure-sliding features of the FOS. Furthermore, relevant stick-slip phenomena associated with the ROS (the transformed problem) are revealed and illustrated in time-domain and phase-space trajectories.

Comparison of Software for Analysis of Risers Tied Back With Pull Tubes

2016 ◽  
Author(s):  
Feng Wang ◽  
Roger Burke ◽  
Alan Yu
Keyword(s):  
Bending Moment ◽  
General Purpose ◽  
Contact Model ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Riser Pipe ◽  
Software Packages ◽  
Steel Catenary Risers ◽  
Vessel Motion ◽  
Von Mises

Dynamic analysis of steel catenary risers (SCRs) tied back to a Spar through pull tubes has most commonly been performed with the general purpose finite element analysis program ABAQUS, which is generally considered to be most suitable for this type of configuration involving pipe-in-pipe contact between the riser and the pull tube. Version 9.6a and subsequent versions of the riser specific software package OrcaFlex include the capability to handle pipe-in-pipe contact through a line contact model. This model is similar to the contact model in ABAQUS in that it supports relative axial motion and axial friction between the contact lines. A benchmark study is performed to compare riser strength and fatigue performance of the two software packages. The focus of the study is on the pull tube and the riser inside the pull tube, where pipe-in-pipe contact occurs. Bending moment and von Mises stress from the two programs in design storms are found to agree closely. Governing loads on the pull tube guides computed with ABAQUS agree well with the loads computed with OrcaFlex. The two software packages compute similar vessel-motion induced fatigue damage of the bottom of the pull tube (pull tube stress joint). Agreement is not as close for the pull tube above the pull tube stress joint or for the riser pipe. Dynamic run times are comparable between the two programs. Results of the study can assist in the selection of the most suitable software for pull tube riser design and analysis, and in understanding the differences in results from the two software packages.

A novel reduced order dynamic model of axial piston motors with compression flow losses and Coulomb friction losses

2019 ◽  
Vol 72 (5) ◽  
pp. 567-573
Author(s):  
Lichen Gu ◽  
Rui Xu ◽  
Nan Wang
Keyword(s):  
Dynamic Model ◽  
Coulomb Friction ◽  
Friction Torque ◽  
Content Type ◽  
Reduced Order ◽  
Flow Losses ◽  
Compression Flow ◽  
Flow Loss ◽  
Torque Loss ◽  
Axial Piston

Purpose The purpose of this paper is to identify the energy losses factors during the hydro-mechanical conversion process at high pressure via a novel reduced order dynamic model. Design/methodology/approach A novel reduced order dynamic model of the axial piston motor was proposed, which provides an explicit insight to the compression flow losses and the Coulomb friction losses. A fully coupled dynamic model of the piston motor was obtained based on the array bond graph method. And then, a reduced order model was obtained by the composition analysis of flow and torque of the axial piston motor. After that, the energy losses estimation model was presented to predict the energy loss of the piston motor under a wide range of working conditions. The model was verified by comparing the experimental and simulation results. Findings The simulation result indicates that the flow loss caused by oil compression accounts for 59 per cent of the total flow loss, and the Coulomb friction torque accounts for 40 per cent of the total torque loss under a specific working condition. The compression flow loss and Coulomb friction torque are the major factors that lead to the aggravation of energy loss under extreme working conditions of the piston motor. Originality/value At high-pressure condition, the compression flow losses due to fluid compressibility cannot be neglected, and the hydro-mechanical losses in varies friction pairs should involve Coulomb friction losses. Flow and torque loss analytical expression in the model involve the design and control parameters of the piston equipment, which can realize the parameter optimization of the piston equipment for the purpose of energy-saving.

A Compliant Contact Model Including Interference Geometry for Space Robotic Systems

2005 ◽  
Author(s):  
Lianzhen Luo ◽  
Meyer Nahon
Keyword(s):  
Material Properties ◽  
Geometric Parameters ◽  
Contact Dynamics ◽  
Robotic Systems ◽  
Space Robotics ◽  
Dynamics Model ◽  
Geometric Algorithm ◽  
Design Cycle ◽  
Simulation Results ◽  
Object Shapes

Modeling of contact with the environment is an essential capability for the simulation of space robotics system, which includes tasks such as berthing and docking. The effect of interbody contact on the robotics system has to be determined to predict potential problems in the design cycle. A compliant contact dynamics model is proposed here, which considers most possible contact situations for a wide diversity of possible object shapes and using interference geometry information. A uniform formula is provided to determine the contact force as a function of geometric parameters and material properties. A corresponding geometric algorithm is provided in order to obtain the necessary geometric parameters. Some simulation results are presented based on the implementation of the geometric algorithm.

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