Modelling of Mechanical Systems With Friction Interfaces Considering Variable Normal Contact Load and Tangential Micro/Macro Slip

2016 ◽  
Author(s):  
Dongwu Li ◽  
Chao Xu
Keyword(s):  
Normal Load ◽  
Friction Model ◽  
Hysteretic Model ◽  
Friction Contact ◽  
Restoring Force ◽  
Normal Contact ◽  
Load Variation ◽  
Proposed Model ◽  
Frictional Damping ◽  
Microslip Friction

Mechanical structures with frictionally constrained interfaces often involve complex contact kinematics induced by tangential and normal relative motions. The tangential motion induces stick-micro/macro slip friction and causes energy dissipation. The normal motion induces normal load variation and possible separation of the joint interfaces. For effective analysis of dynamics of jointed structures, a reduced friction contact model is needed to characterize the nonlinear, coupled normal and tangential contact behaviors precisely. However, most developed microslip friction contact models considers only constant normal load. In this paper, an improved microslip friction model with normal load variation induced by normal motion is proposed. The tangential stick-micro/macro slip friction is modeled by continuous Iwan hysteretic model. This model is characterized by a slippage uniform distribution density function and a linear stiffness at stick state. The coupling relationship between tangential nonlinear restoring force and normal load variation is built. This leads to generalization of the original Iwan hysteretic friction model to consider the effect of variable normal load. The proposed model is applied to model a 7-dofs frictional damping experimental system. The results show that normal load variation and tangential microslip motion exert an important effect on prediction of friction contact behaviors. The proposed model is capable of generating asymmetric hysteresis loops and intermittent normal separation. The numerical simulation fit well with the experimental results for the 7-dofs frictional damping system, which validates the effectiveness and accuracy of the proposed model.

A microslip friction model with normal load variation induced by normal motion

2007 ◽  
Vol 50 (3) ◽  
pp. 609-626 ◽  
Author(s):  
Ender Cigeroglu ◽  
Ning An ◽  
Chia-Hsiang Menq
Keyword(s):  
Normal Load ◽  
Friction Model ◽  
Load Variation ◽  
Microslip Friction

Response Prediction of Frictionally Constraint Blade Systems Based on a Variable Normal Load Microslip Model

2010 ◽  
Author(s):  
Yalin Liu ◽  
Zili Xu ◽  
Shangguan Bo ◽  
Linzhong Li
Keyword(s):  
Time Domain ◽  
Degrees Of Freedom ◽  
Normal Load ◽  
Response Prediction ◽  
Friction Model ◽  
Time Dependent ◽  
Friction Contact ◽  
Contact Kinematics ◽  
Multiple Variables ◽  
Microslip Friction

A discrete microslip friction contact model, which can consider time-dependent/space-related normal load, has been established to investigate the contact kinematics in the contact interfaces between adjacent blade shrouds. The model extends the capability of Csaba’s model in dealing with the situation of variant normal load. A Fast Anti-alias Fourier transform (FAFT) is introduced to the alternating frequency/time domain method (AFT) to improve the accuracy of spectrum analysis and extend analysis spectrum range. The developed friction model and the modified AFT are applied to calculate nonlinear vibration for a simplified shrouded blade, and the effect of parameters on resonant frequency and amplitude of shrouded blade are investigated and discussed. Comparing with existing variable normal load macroslip model, the model proposed here has the mathematically tractable characteristic and can be easily used. Combining with the AFT method, it is suitable for the analysis of complex system with multiple variables and degrees of freedom, and it can meet the engineering need.

A Fractal Contact Friction Model and Nonlinear Vibration Response Studies of Loosely Assembled Blade With Dovetail Root

2016 ◽  
Author(s):  
Shangguan Bo ◽  
Yu Feilong ◽  
Duan Jingyao ◽  
Gao Song ◽  
Xiao Junfeng ◽  
...  
Keyword(s):  
Nonlinear Vibration ◽  
Fractal Geometry ◽  
Friction Model ◽  
Structure Design ◽  
Forced Response ◽  
Vibration Response ◽  
Contact Friction ◽  
Friction Contact ◽  
Stick Slip ◽  
Proposed Model

To investigate the friction damping effect of a loosely assembled blade with dovetail root, a fractal contact friction model is proposed to describe the friction force. In the proposed model, the friction contact interface is discretized to a series of friction contact pairs and each of them can experience stick, slip, or separate. Fractal geometry is used to simulate the topography of contact surfaces. The contact stiffness, which is related to the parameters of contact interfaces including normal load, roughness, Young’s modulus, and Poisson’s ratio, is calculated using Hertz contact theory and fractal geometry. The nonlinear vibration response of loosely assembled blade with dovetail root is predicted using the proposed model, the multiharmonic balance method and Newton iterative algorithm. The effect of centrifugal force, friction coefficient and exciting force on the forced response of a loosely assembled blade with dovetail root is studied. The numerical vibration responses are compared to the experimental results. It will verify the reliability of the numerical method and provide theoretical basis for structure design of the loosely assembled blade with dovetail root.

Frictional Damping of Flutter: Microslip Versus Macroslip

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Robert Hudson ◽  
Alok Sinha
Keyword(s):  
Harmonic Balance ◽  
Function Method ◽  
Friction Model ◽  
Describing Function ◽  
Friction Dampers ◽  
Method Of Harmonic Balance ◽  
Frictional Damping ◽  
Negative Damping ◽  
Describing Function Method ◽  
Microslip Friction

Friction dampers are utilized in turbomachinery to reduce blade vibrations resulting from aeroelastic interactions. In this paper, the microslip friction model is applied to a blade with blade to ground damper and subjected to negative damping. Analysis using the describing function method, also known as the method of harmonic balance, is used to identify the behavior of the system and the maximum negative damping that can be stabilized by such a damper. These results are compared to those for the macroslip friction model.

Static Friction Model for Rough Surfaces With Asymmetric Distribution of Asperity Heights

2004 ◽  
Vol 126 (3) ◽  
pp. 626-629 ◽  
Author(s):  
Ning Yu, ◽  
Shaun R. Pergande, and ◽  
Andreas A. Polycarpou
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Static Friction ◽  
Friction Model ◽  
Published Data ◽  
Asymmetric Distribution ◽  
Adhesion Forces ◽  
Normal Contact ◽  
Static Friction Coefficient ◽  
Gaussian Case

The CEB static friction model is extended to include asymmetric distributions of asperity heights, using the normalized one-parameter Weibull distribution. The normal contact, tangential (friction), and adhesion forces are calculated for different skewness values, and are used to obtain the static friction coefficient. It is predicted that surfaces with negative skewness experience higher static friction coefficient compared to the Gaussian case, under the same external normal load, which agrees with published data. This effect is magnified for lower external loads, as is commonly encountered in microtribological applications.

scholarly journals Nonlinear Dynamic Analysis of Seismically Base-Isolated Structures by a Novel OpenSees Hysteretic Material Model

2021 ◽  
Vol 11 (3) ◽  
pp. 900
Author(s):  
Nicoló Vaiana ◽  
Raffaele Capuano ◽  
Salvatore Sessa ◽  
Francesco Marmo ◽  
Luciano Rosati
Keyword(s):  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Material Model ◽  
Model Parameters ◽  
Hysteretic Model ◽  
Restoring Force ◽  
Nonlinear Dynamic Response ◽  
Elastomeric Bearings ◽  
Software Products ◽  
Proposed Model

The complex response characterizing elastomeric isolation bearings is reproduced by employing a novel uniaxial hysteretic model that has been recently formulated and successfully implemented in OpenSees. Such a novel OpenSees material model offers several advantages with respect to differential models typically available in commercial software products for structural analysis, such as 3D-BASIS and CSi programs. Firstly, it is based on a set of only five model parameters that have a clear mechanical significance; such a property not only allows one to drastically simplify the parameters identification process, but it also allows the model to be used in practice. In addition, the model does not require numerical methods for the evaluation of the restoring force since the latter is computed by solving an algebraic equation. To encourage researchers and designers to adopt the proposed model for research and practical purposes, we demonstrate its accuracy by performing some numerical tests in OpenSees. In particular, we first employ the recently implemented model to compute the nonlinear dynamic response of a seismically base-isolated structure with elastomeric bearings and, subsequently, we compare the results with those obtained by modeling the seismic isolators with the OpenSees BoucWen uniaxial material model, that is one of the most popular and accurate hysteretic models currently available in OpenSees.

Modeling Tangential Contact of Rough Surfaces With Elastic- and Plastic-Deformed Asperities

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Dong Wang ◽  
Chao Xu ◽  
Qiang Wan
Keyword(s):  
Rough Surface ◽  
Normal Load ◽  
Experimental Results ◽  
Partial Slip ◽  
Tangential Load ◽  
Stick Slip ◽  
Normal Contact ◽  
Tangential Contact ◽  
Bilinear Relation ◽  
Proposed Model

A new tangential contact model between a rough surface and a smooth rigid flat is proposed in this paper. The model considers the contribution of both elastically deformed asperities and plastically deformed asperities to the total tangential load of rough surface. The method combining the Mindlin partial slip solution with the Hertz solution is used to model the contact formulation of elastically deformed asperities, and for the plastically deformed asperities, the solution combining the fully plastic theory of normal contact with the bilinear relation between the tangential load and deformation developed by Fujimoto is implemented. The total tangential contact load is obtained by Greenwood and Williamson statistical analysis procedure. The proposed model is first compared to the model considering only elastically deformed asperities, and the effect of mean separation and plasticity index on the relationship between the tangential load and deformation is also investigated. It is shown that the present model can be used to describe the stick–slip behavior of the rough surface, and it is a more realistic-based model for the tangential rough contact. A comparison with published experimental results is also made. The proposed model agrees very well with the experimental results when the normal load is small, and shows an error when the normal load is large.

scholarly journals An Analytical Model of Multiarc Sprag Clutch considering Geometry and Internal Interaction during Engagement

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Chuang Huang ◽  
Ming Liu ◽  
Yongqiang Zhao
Keyword(s):  
Friction Model ◽  
Contact Radius ◽  
Rate Dependency ◽  
Fem Model ◽  
Normal Contact ◽  
Outer Race ◽  
Dynamical Behaviors ◽  
Proposed Model ◽  
Internal Interaction ◽  
Improved Model

A new multiarc sprag clutch model considering geometry and internal interaction during engagement is proposed in this paper. To increase the accuracy of the model, an improved model of geometric deformation coordination is presented to describe the basic geometrical quantities after rotation of the sprag. Then, based on this model, a novel nonlinear iteration method focusing on the varied contact radius is proposed to compute the normal contact force and show a good agreement with the FEM model. In addition, the alternate friction model considering stationary and rate-dependency friction is formulated and applied in the contacts of both the inner race and outer race. The proposed model is verified by comparison with other published results and experimental results. In subsequent analysis, the new model fully reveals the dynamical behaviors of the multiarc clutch during preload engagement under torque excitation; therefore, it will be useful for the performance analysis and dynamic design of multiarc sprag clutch.

Frictional Damping of Flutter: Microslip Versus Macroslip

2016 ◽  
Author(s):  
Robert B. Hudson ◽  
Alok Sinha
Keyword(s):  
Harmonic Balance ◽  
Function Method ◽  
Friction Model ◽  
Describing Function ◽  
Friction Dampers ◽  
Method Of Harmonic Balance ◽  
Frictional Damping ◽  
Negative Damping ◽  
Describing Function Method ◽  
Microslip Friction

Friction dampers are utilized in turbomachinery to reduce blade vibrations resulting from aeroelastic interactions. In this paper, the microslip friction model is applied to a blade with blade to ground damper and subjected to negative damping. Analysis using the describing function method, also known as the method of harmonic balance, is used to identify the behavior of the system and the maximum negative damping that can be stabilized by such a damper. These results are compared to those for the macroslip friction model.

Influence of Clearances and Thermal Effects on the Dynamic Behavior of Gear-Hydrodynamic Journal Bearing Systems

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
R. Fargère ◽  
P. Velex
Keyword(s):  
Degrees Of Freedom ◽  
Integration Scheme ◽  
Time Step ◽  
Specific Element ◽  
Normal Contact ◽  
Contact Algorithm ◽  
Gear Teeth ◽  
Proposed Model ◽  
Elastic Couplings ◽  
Definition Of

A global model of mechanical transmissions is introduced which deals with most of the possible interactions between gears, shafts, and hydrodynamic journal bearings. A specific element for wide-faced gears with nonlinear time-varying mesh stiffness and tooth shape deviations is combined with shaft finite elements, whereas the bearing contributions are introduced based on the direct solution of Reynolds' equation. Because of the large bearing clearances, particular attention has been paid to the definition of the degrees-of-freedom and their datum. Solutions are derived by combining a time step integration scheme, a Newton–Raphson method, and a normal contact algorithm in such a way that the contact conditions in the bearings and on the gear teeth are simultaneously dealt with. A series of comparisons with the experimental results obtained on a test rig are given which prove that the proposed model is sound. Finally, a number of results are presented which show that parameters often discarded in global models such as the location of the oil inlet area, the oil temperature in the bearings, the clearance/elastic couplings interactions, etc. can be influential on static and dynamic tooth loading.

Sign in / Sign up

Export Citation Format

Share Document