Modelling Transient Behavior of a Mechanical System Including a Rolling and Sliding Contact

Tribology ◽  
2005 ◽  
Author(s):  
Anders So¨derberg ◽  
Christer Spiegelberg
Keyword(s):  
Contact Stiffness ◽  
Transient Behavior ◽  
Measurement Procedure ◽  
Sliding Contact ◽  
Contact Model ◽  
Test Equipment ◽  
Main Concern ◽  
Contact Conditions ◽  
Machine Elements ◽  
Precision Machines

The friction and wear of rolling and sliding contacts are critical factors for the operation of machine elements such as bearings, gears, and cam mechanisms. In precision machines, for example, the main concern is to compensate for frictional losses, so as to improve control accuracy. In other applications it is often desirable to minimize friction losses to improve efficiency, though sometimes high friction is desired to prevent sliding and wear. The aim of this study is to simulate the behavior of a test equipment and show that simulations can be used to study and optimize mechanical systems that include rolling and sliding contact. Simulations can be used to study the system as a whole, as well as the contact conditions. The test equipment and the measurement procedure used are described. In the simulations, a contact model designed to handle transient contact conditions is integrated into a system model. The results show that the contact strongly influences the system. The simulations show that the use of a contact model allows the simulation of systems that contain contacts with different amounts of slip, and that such simulations can be used to study the contact as well as the system. Surface roughness influences the contact stiffness and is included in the simulations.

Generalized Abbe Principle: Position Error Propagation in Machine Elements

1996 ◽  
Author(s):  
Joseph Pegna
Keyword(s):  
Error Propagation ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Statistical Characterization ◽  
Physical Limit ◽  
Potential Applications ◽  
Machine Elements ◽  
Tolerance Verification ◽  
Precision Machines

Abstract In the quest for ever finer levels of technology integration, mechanical linkages reach their precision limits at about 5micrometers per meter of workspace. Beyond this physical limit, all six dimensional degrees of freedom need to be precisely ascertained to account for mechanical imperfections. This paper substantiates Wu’s vision of “precision machines without precision machinery.” A formulation and statistical characterization of position and orientation error propagation in rigid bodies are presented for two extreme models of measurement. It is shown that error distribution is uniquely dependent upon the design of the measurement plan. The theoretical foundations presented were evolved in the course of designing precision machinery. Other potential applications include: fixture design, metrology, and geometric tolerance verification.

Elastic Contact Model Accounting for Both Asperity and Substrate Compliance With Application to Patterned Media

2007 ◽  
Author(s):  
Chang-Dong Yeo ◽  
Andreas A. Polycarpou
Keyword(s):  
Bulk Material ◽  
Contact Stiffness ◽  
Contact Model ◽  
Elastic Contact ◽  
Element Analysis ◽  
Patterned Media ◽  
Single Asperity ◽  
Proposed Model ◽  
Stiffness Model ◽  
Bulk Substrate

An improved elastic contact stiffness model for a single asperity system is proposed to account for the effects of both bulk substrate and asperity deformations between two contacting surfaces. Depending upon the applied load, as well as the geometrical and physical properties of the asperity and bulk material, the bulk substrate can have a considerable contribution to the overall contact stiffness. Finite element analysis is performed to verify the proposed analytical model. The single asperity model is extended to rough surfaces in contact. The contact stiffness values from the proposed model are compared to those from the GW model. The proposed contact model can be directly relevant to analyze the contact behavior of modern patterned media.

Viscoelastic Contact of a Half-Plane Sliding Over a Slightly Wavy Rigid Surface

2014 ◽  
Author(s):  
N. Menga ◽  
C. Putignano ◽  
T. Contursi ◽  
G. Carbone
Keyword(s):  
Contact Problem ◽  
Contact Area ◽  
Analytical Procedure ◽  
Sliding Contact ◽  
Rigid Surface ◽  
Viscoelastic System ◽  
Contact Conditions ◽  
Partial Contact ◽  
Full Contact ◽  
Viscoelastic Contact

In this paper, the sliding contact of a rigid sinusoid over a viscoelastic halfplane is studied by means of an analytical procedure that reduced the original viscoelastic system to an elastic equivalent one, which has been already solved in [1]. In such a way, the solution of the original viscoelastic contact problem requires just to numerically solve a set of two integral equations. Results show the viscoelasticity influence on the solution by means of a detailed analysis of contact area, pressure and displacement distribution. A particular attention is paid to the transition from full contact to partial contact conditions.

Contact Stiffness Parameters for Finite Element Modeling of Contact

2019 ◽  
Vol 799 ◽  
pp. 211-216
Author(s):  
Alina Sivitski ◽  
Priit Põdra
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Contact Stiffness ◽  
Influential Factors ◽  
Element Analysis ◽  
Normal Contact ◽  
Element Modeling ◽  
Contact Models ◽  
Machine Elements ◽  
Normal Contact Pressure

Contact modeling could be widely used for different machine elements normal contact pressure calculations and wear simulations. However, classical contact models as for example Hertz contact models have many assumptions (contact bodies are elastic, the contact between bodies is ellipse-shaped, contact is frictionless and non-conforming). In conditions, when analytical calculations cannot be performed and experimental research is economically inexpedient, numerical methods have been applied for solving such engineering tasks. Contact stiffness parameters appear to be one of the most influential factors during finite element modeling of contact. Contact stiffness factors are usually selected according to finite element analysis software recommendations. More precise analysis of contact stiffness parameters is often required for finite element modeling of contact.

610 Effects of Slip Ratio and Roller Combination on Durability of Thermally Sprayed wc Cerment Coating under Dry Rolling/Sliding Contact Conditions

2012 ◽  
Vol 2012.65 (0) ◽  
pp. 211-212
Author(s):  
Toshifumi MAWATARI ◽  
Yusuke ARAKI ◽  
Ryosuke INOKUCHI ◽  
Bo ZHANG ◽  
Akira NAKAJIMA ◽  
...  
Keyword(s):  
Sliding Contact ◽  
Contact Conditions ◽  
Slip Ratio ◽  
Thermally Sprayed

A Contact Model for Nonlinear Forced Response Prediction of Turbine Blades: Calculation Techniques and Experimental Comparison

2008 ◽  
Author(s):  
Christian M. Firrone ◽  
Marco Allara ◽  
Muzio M. Gola
Keyword(s):  
Normal Load ◽  
Contact Stiffness ◽  
Turbine Blades ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Contact Forces ◽  
Contact Model ◽  
Experimental Comparison ◽  
Normal Contact ◽  
Contact Models

Dry friction damping produced by sliding surfaces is commonly used to reduce vibration amplitude of blade arrays in turbo-machinery. The dynamic behavior of turbine components is significantly affected by the forces acting at their contact interfaces. In order to perform accurate dynamic analysis of these components, contact models must be included in the numerical solvers. This paper presents a novel approach to compute the contact stiffness of cylindrical contacts, analytical and based on the continuous contact mechanics. This is done in order to overcome the known difficulties in simultaneously adjusting the values of both tangential and normal contact stiffness experimentally. Monotonic loading curves and hysteresis cycles of contact forces vs. relative displacement are evaluated as a function of the main contact parameters (i.e. the contact geometry, the material properties and the contact normal load). The new contact model is compared with other contact models already presented in literature in order to show advantages and limitations. The contact model is integrated in a numerical solver, based on the Harmonic Balance Method (HBM), for the calculation of the forced response of turbine components with friction contacts, in particular underplatform dampers. Results from the nonlinear numerical simulations are compared with those from validation experiments.

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