A Regularized Contact Model for Multibody System Simulation

2016 ◽  
Author(s):  
Albert Peiret ◽  
Farnood Gholami ◽  
József Kövecses ◽  
Josep M. Font-Llagunes
Keyword(s):  
Multibody Systems ◽  
Large Scale ◽  
Multibody System ◽  
Linear Complementarity Problems ◽  
Friction Model ◽  
Computational Performance ◽  
Unilateral Contacts ◽  
Wheel Model ◽  
Friction Models ◽  
Coulomb Model

Simulation of large-scale multibody systems with unilateral contacts requires formulations with which good computational performance can be achieved. The availability of many solver algorithms for Linear Complementarity Problems (LCP) makes the LCP-based formulations a good candidate for this. However, considering friction in contacts asks for new friction models compatible with this kind of formulations. Here, a new, regularized friction model is presented to approximate the Coulomb model, which allows to formulate the multibody system dynamics as a LCP with bounds. Moreover, a bristle approach is used to approximate the stiction force, so that it improves the numerical behaviour of the system and makes it able to handle redundancy coming from the friction interfaces. Several examples using a 3D wheel model has been carried out, and the proposed friction model shows a better approximation of the Coulomb model compared to other LCP-based formulations.

A Friction Model for Non-Singular Complementarity Formulations for Multibody Systems With Contacts

2017 ◽  
Author(s):  
Albert Peiret ◽  
József Kövecses ◽  
Josep M. Font-Llagunes
Keyword(s):  
Multibody Systems ◽  
Iterative Algorithms ◽  
Full Rank ◽  
Linear Complementarity ◽  
Friction Model ◽  
Physical Problem ◽  
The Other ◽  
Dynamics Of Multibody Systems ◽  
Friction Models ◽  
Coulomb Model

The dynamics of multibody systems with many contacts are frequently formulated as a Linear Complementarity Problem (LCP), for which several direct or iterative algorithms are available to solve it efficiently. These formulations rely on discretized friction models that approximate the friction cone of the Coulomb model to a pyramid. However, they produce rank-deficient LCPs even though the physical problem does not have constraint redundancy and has a unique solution. Here, a new discretized friction model is presented which results in an LCP formulation with a full-rank lead matrix. This model relies on an inertial term to couple the equations of the model, which behaves as close to the Coulomb model as the other discretized models. Moreover, it is shown through some simulations that some algorithms can be used with this formulation, which could not be used with the other rank-deficient LCP formulations.

Ensemble Grey and Black-box Nonlinear System Identification of a Positioning System

2020 ◽  
Author(s):  
Walisson Chaves Ferreira Pinto ◽  
Helon Vicente Hultmann Ayala
Keyword(s):  
Nonlinear System ◽  
Nonlinear System Identification ◽  
Viscous Friction ◽  
Black Box ◽  
Friction Model ◽  
Model Construction ◽  
Ensemble Model ◽  
Positioning System ◽  
Friction Models ◽  
Coulomb Model

In this work, grey and black-box approaches are used in order to model a electromechanical positioning system (EMPS). An ensemble model is then constructed by combining these two approaches, by using the predictions of both models in order to generate an improved estimated output. Four friction models, in their symmetric and asymmetric versions,namely (i) Coulomb model with finite slope at zero velocity and viscous friction, (ii) Coulomb model with viscous friction, (iii) Tustin friction model, (iv) Coulomb model with viscous friction and Stribeck effect were used to describe the dynamic behavior of the EMPS. The results have shown that the combination of grey and black-box models was able to perform better than the grey-box model and that the proposed friction models are also able to improve the relativeerror. This encourages further research on the application of the concept of ensemble model construction from machine learning to the nonlinear system identication context towards more accurate model construction.

Dynamics of Roller Coasters

2005 ◽  
Author(s):  
Friedrich Pfeiffer
Keyword(s):  
Multibody Systems ◽  
Multibody System ◽  
Roller Coaster ◽  
Stick Slip ◽  
Unilateral Contacts ◽  
Raceway Design ◽  
Impacts With Friction

Roller coasters are dynamically multibody systems with unilateral contacts due to the usual raceway design including straight parts and bends. In running down such tracks and passing parts of the track with changing curvature impacts with friction are generated in the track-wheel contacts. The impacts are always connected with large overloads of the wheels sometimes leading to damages. To investigate these problems the roller coaster carriages are modelled as a non-smooth multibody system with impacts and stick-slip processes. The results in terms of wheel loads are used to improve wheel design.

scholarly journals Efficiency comparison of various friction models of a hydraulic cylinder in the framework of multibody system dynamics

2021 ◽  
Author(s):  
Suraj Jaiswal ◽  
Jussi Sopanen ◽  
Aki Mikkola
Keyword(s):  
System Dynamics ◽  
Dynamic Simulation ◽  
Multibody System ◽  
Hydraulic Cylinder ◽  
Friction Model ◽  
Multibody System Dynamics ◽  
Lugre Model ◽  
Work Cycle ◽  
Hydraulically Actuated ◽  
Friction Models

AbstractDynamic simulation of mechanical systems can be performed using a multibody system dynamics approach. The approach allows to account systems of other physical nature, such as hydraulic actuators. In such systems, the nonlinearity and numerical stiffness introduced by the friction model of the hydraulic cylinders can be an important aspect to consider in the modeling because it can lead to poor computational efficiency. This paper couples various friction models of a hydraulic cylinder with the equations of motion of a hydraulically actuated multibody system in a monolithic framework. To this end, two static friction models, the Bengisu–Akay model and Brown–McPhee model, and two dynamic friction models, the LuGre model and modified LuGre model, are considered in this work. A hydraulically actuated four-bar mechanism is exemplified as a case study. The four modeling approaches are compared based on the work cycle, friction force, energy balance, and numerical efficiency. It is concluded that the Brown–McPhee approach is numerically the most efficient approach and it is well able to describe usual friction characteristics in dynamic simulation of hydraulically actuated multibody systems.

scholarly journals A Review on the Application of Friction Models in Wheel-Rail Adhesion Calculation

2021 ◽  
Vol 7 (1) ◽  
pp. 1-11
Author(s):  
Zewang Yuan ◽  
Mengling Wu ◽  
Chun Tian ◽  
Jiajun Zhou ◽  
Chao Chen
Keyword(s):  
Structural Characteristics ◽  
Critical Role ◽  
Exponential Model ◽  
Friction Model ◽  
Rational Model ◽  
Friction Behavior ◽  
Normal Forces ◽  
Interface Modeling ◽  
Friction Models ◽  
Coulomb Model

AbstractFriction is the bond linking the tangential and normal forces at the wheel-rail interface. Modeling friction is the precondition for the wheel-rail adhesion calculation. In this work, the critical role of friction in the calculation of wheel-rail adhesion is discussed. Four types of friction models (Coulomb model, linear model + Coulomb model, rational model and exponential model) which are commonly used for the calculation of wheel-rail adhesion are reviewed, in particular with regard to their structural characteristics and application state. The adhesion coefficients calculated from these four friction models using the Polach model are analyzed by comparison with the measured values. The rational model and the exponential model are more flexible for defining the falling friction, and the adhesion coefficient calculated by these two models is highly consistent with the measured one. Though the rational model and exponential model describe the falling friction well, the existing friction models are not applicable for calculating adhesion after considering more realistic factors, such as thermal effect, contaminants and so on. Developing a novel and practical friction model to accurately describe the wheel-rail friction behavior is still an essential but challenging and significant task. This review provides a reference for the selection of existing friction models and generates fresh insights into developing novel and practical friction models.

scholarly journals A new version of the Riccati transfer matrix method for multibody systems consisting of chain and branch bodies

2019 ◽  
Vol 49 (3) ◽  
pp. 337-354 ◽  
Author(s):  
Xue Rui ◽  
Dieter Bestle ◽  
Guoping Wang ◽  
Jiangshu Zhang ◽  
Xiaoting Rui ◽  
...  
Keyword(s):  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Multibody System ◽  
Branch System ◽  
Computational Speed ◽  
Speed Accuracy

Abstract Computational speed and stability are two important aspects in the dynamics analysis of large-scale complex multibody systems. In order to improve both in the context of the multibody system transfer matrix method, a new version of the Riccati transfer matrix method is presented. Based on the new version of the general transfer matrix method for multibody system simulation, recursive formulae are developed which not only retain all advantages of the transfer matrix method, but also reduce the truncation error. As a result, the computational speed, accuracy and efficiency are improved. Numerical computation results obtained by the proposed method and an ordinary multibody system formulation show good agreement. The successful computation for a spatial branch system with more than 100000 degrees of freedom validates that the proposed method is also working for huge systems.

Energy Analysis and Decoupling in Three-Dimensional Impacts of Multibody Systems

2006 ◽  
Vol 74 (5) ◽  
pp. 845-851 ◽  
Author(s):  
Seyed Ali Modarres Najafabadi ◽  
József Kövecses ◽  
Jorge Angeles
Keyword(s):  
Kinetic Energy ◽  
Energy Absorption ◽  
Multibody Systems ◽  
Energy Analysis ◽  
Multibody System ◽  
Energy Content ◽  
Three Dimensional ◽  
Unilateral Contacts ◽  
Potential Applications

This paper discusses an exact decomposition of the kinetic energy to determine the energy content that influences the dynamics of unilateral contacts in multibody systems. This decomposition essentially divides the kinetic energy of the whole multibody system into two completely decoupled parts associated with the constrained and admissible directions of unilateral contacts. This will provide a picture of how the energy absorption/dissipation during impacts is related to the variation of the generalized velocities and the configuration of multibody systems. Potential applications of such a decoupling are highlighted.

scholarly journals An Improvement Proposal to the Static Friction Model

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Sergio Sánchez-Mazuca ◽  
Ricardo Campa
Keyword(s):  
Large Scale ◽  
Static Friction ◽  
Control Area ◽  
Friction Model ◽  
Rate Of Change ◽  
Direct Drive ◽  
Mechatronic Systems ◽  
Proposed Model ◽  
Drive Motor ◽  
Friction Models

Friction is a force acting against the relative motion between two surfaces in contact. This phenomenon is present in all mechanical systems and has a great impact on the control area. The design of mechatronic systems and the compensation techniques require a broad knowledge of the effects that friction produces. The phenomenon has two well-defined phases: static friction presents before the motion between the surfaces in contact is clearly visible, while kinetic friction appears when that motion at large scale has already started. There are different friction models for each of those phases. In this work we propose an improvement to the static friction models, which consist in assuming that the maximum static friction coefficient is no more a constant but a function of the rate of change of the external force that produces the motion. After explaining and justifying the proposal, the procedure for obtaining the parameters of the new model is mentioned. At the end, an experimental study on a direct-drive motor allows us to validate the proposed model.

Modeling of Piezo-Actuated Stick-Slip Micro-Drives: An Overview

2012 ◽  
Vol 81 ◽  
pp. 39-48 ◽  
Author(s):  
Ha Xuan Nguyen ◽  
Christoph Edeler ◽  
Sergej Fatikow
Keyword(s):  
Mechanical Model ◽  
Integrated Model ◽  
Friction Model ◽  
Fundamental Importance ◽  
Future Research ◽  
Stick Slip ◽  
Research Activities ◽  
Model Combining ◽  
Friction Models

This paper gives an overview about problems of modeling of piezo-actuated stick-slip micro-drives. It has been found that existing prototypes of such devices have been investigated empirically. There is only few research dealing with the theory behind this kind of drives. By analyzing the current research activities in this field, it is believed that the model of the drive depends strongly on the friction models, but in most cases neglecting any influences of the guilding system.These analyses are of fundamental importance for an integrated model combining friction model and mechanical model offering promising possibilities for future research.

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