Two-Dimensional Thermal Model of Asperity Heating in a Disk Pair in Dry Friction Between Two Rough Surfaces

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
A. Elhomani ◽  
K. Farhang
Keyword(s):  
Heat Generation ◽  
Dry Friction ◽  
Rough Surfaces ◽  
Frictional Heating ◽  
Heat Rate ◽  
Lumped Parameter Model ◽  
Disk Brake ◽  
Braking System ◽  
Lumped Parameter ◽  
Rate Formulation

In this paper, a formulation for the rate of heat generation due to the contact of one asperity with asperities on a second surface is proposed. A statistical approach is used to obtain the heat generation rate due to one asperity and employed to develop the equation for generation of heat rate between two rough surfaces. This heat rate formulation between the two rough surfaces has been incorporated into the 2D lumped parameter model of disk pair in dry friction developed by Elhomani and Farhang (2010, “A 2D Lumped Parameter Model for Prediction of Temperature in C/C Composite Disk Pair in Dry Friction Contact,” ASME J. Therm. Sci. Eng. Appl., 2(2), p. 021001). In this paper, the disk brake is viewed as consisting of three main regions: (1) the surface contact, (2) the friction interface, and (3) the bulk. Both surfaces of the disk brake are subjected to frictional heating. This model is considered to be a necessary step for simulating the aircraft braking system that consists of a stack of multiple disks.

A 2D Lumped Parameter Model for Prediction of Temperature in C/C Composite Disk Pair in Dry Friction Contact

2010 ◽  
Vol 2 (2) ◽  
Author(s):  
A. Elhomani ◽  
K. Farhang
Keyword(s):  
Dry Friction ◽  
Lumped Parameter Model ◽  
Interface Temperature ◽  
Dynamic Nature ◽  
Thermomechanical Model ◽  
Disk Brake ◽  
System A ◽  
Surface Failure ◽  
Lumped Parameter ◽  
Thermal Capacitance

In applications involving substantial friction, surface failure is an inevitable phenomenon. Friction induced failure typically involves the generation of considerable heat. Existence of significant frictional force leads to relatively high interface temperature as a result of dynamic nature of flash temperatures at the contact areas. A first step in predicting friction induced failure is to develop an accurate thermomechanical model of the friction system. A thermomechanical model is developed in this paper based on a lumped parameter representation of a two-disk brake. A disk is viewed as consisting of three main regions: (1) the surface contact, (2) the friction interface, and (3) the bulk. The lumped parameter model is obtained by dividing a disk into a number of concentric rings and stacked layers. The friction layer contains both the interface and contact elements, each includes the equivalent thermal capacitance and conductive resistance. The contact capacitance and resistance are described in terms of the elastic contact interaction between the surfaces of the two disks. Therefore, they are obtained using the Greenwood and Williamson model for contact of rough surfaces. Each is described as a statistical summation of the micron-scale interaction of the surfaces.

A Lumped Parameter Model for Prediction of Temperature in Disk Pair in Dry Friction Contact

2007 ◽  
Author(s):  
A. Elhomani ◽  
K. Farhang ◽  
M. Krkoska
Keyword(s):  
Carbon Composite ◽  
Lumped Parameter Model ◽  
Bulk Temperature ◽  
Interface Temperature ◽  
Thermomechanical Model ◽  
Disk Brake ◽  
System A ◽  
Surface Failure ◽  
Lumped Parameter ◽  
Thermal Capacitance

In applications involving substantial friction, surface failure is an inevitable phenomenon. Friction induced failure typically involves the generation of considerable heat. Existence of significant frictional force leads to relatively high interface temperature as a result of dynamic nature of flash temperatures at the contact areas. A first step in predicting friction induced failure is to develop an accurate thermomechanical model of the friction system. A thermo-mechanical model is developed in this paper based on a lumped parameter representation of a two-disk brake. A disk is viewed as consisting of three main regions, (1) the surface contact, (2) the friction interface, and (3) the bulk. The lumped parameter model is obtained by dividing a disk into a number of concentric rings and stacked layers. The friction layer contains both the interface and contact elements, each include the equivalent thermal capacitance and conductive resistance. The contact capacitance and resistance are described in terms of the elastic contact interaction between the surfaces of the two disks. Therefore they are obtained using the Greenwood and Williamson model for contact of rough surfaces. Each is described as a statistical summation of the micron-scale interaction of the surfaces. The model is shown to provide accurate prediction of bulk temperature using a dynamometer test on a carbon composite disk pair.

Influence of Friction Dampers on Torsional Blade Flutter

1986 ◽  
Vol 108 (2) ◽  
pp. 313-318 ◽  
Author(s):  
A. Sinha ◽  
J. H. Griffin ◽  
R. E. Kielb
Keyword(s):  
Dry Friction ◽  
Fluid Velocity ◽  
Supersonic Flows ◽  
Degree Of Freedom ◽  
Lumped Parameter Model ◽  
Single Degree Of Freedom ◽  
Friction Dampers ◽  
Single Degree ◽  
Lumped Parameter ◽  
Blade Flutter

This paper deals with the stabilizing effects of dry friction on torsional blade flutter. A lumped parameter model with single degree of freedom per blade has been used to represent the rotor stage. The well-known cascade theories for incompressible and supersonic flows have been used to determine the allowable increase in fluid velocity relative to the blade. It has been found that the effectiveness of friction dampers in controlling flutter can be substantial.

A Model for Prediction of Temperature in Disk Pair in Dry Friction Contact

2007 ◽  
Author(s):  
A. Homani ◽  
K. Farhang
Keyword(s):  
Mechanical Model ◽  
Carbon Composite ◽  
Lumped Parameter Model ◽  
Bulk Temperature ◽  
Interface Temperature ◽  
Disk Brake ◽  
System A ◽  
Surface Failure ◽  
Lumped Parameter ◽  
Thermal Capacitance

In applications involving substantial friction, surface failure is an inevitable phenomenon. Friction induced failure typically involves the generation of considerable heat. Existence of significant frictional force leads to relatively high interface temperature as a result of dynamic nature of flash temperatures at the contact areas. A first step in predicting friction induced failure is to develop an accurate thermo-mechanical model of the friction system. A thermo-mechanical model is developed in this paper based on a lumped parameter representation of a two-disk brake. A disk is viewed as consisting of three main regions, (1) the surface contact, (2) the friction interface, and (3) the bulk. The lumped parameter model is obtained by dividing a disk into a number of concentric rings and stacked layers. The friction layer contains both the interface and contact elements, each include the equivalent thermal capacitance and conductive resistance. The contact capacitance and resistance are described in terms of the elastic contact interaction between the surfaces of the two disks. Therefore they are obtained using the Greenwood and Williamson model for contact of rough surfaces. Each is described as a statistical summation of the micron-scale interaction of the surfaces. The model is shown to provide accurate prediction of bulk temperature using a dynamometer test on a carbon composite disk pair.

scholarly journals Extraction of Features due to Breathing Crack from Vibration Response of Rotated Blades considering Tenon Connection and Shroud Contact

2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Faming Yang ◽  
Yongmin Yang ◽  
Haifeng Hu ◽  
Fengjiao Guan ◽  
Guoji Shen ◽  
...  
Keyword(s):  
Dry Friction ◽  
Online Monitoring ◽  
Vibration Response ◽  
Lumped Parameter Model ◽  
Breathing Crack ◽  
Online Identification ◽  
Bladed Disk ◽  
Lumped Parameter ◽  
Frequency Domains ◽  
Coupling Force

Cracks are common failures of aeroengine rotated blades. Online monitoring of rotated blades through their vibration to identify cracks early in various working conditions is significant for operational safety. Breathing crack is a practical form of early cracks and results in nonlinear vibration response. Tenon connection and shroud contact are common structures in aeroengine rotated blades, which can also lead blades to vibrate nonlinearly and seriously interfere online identification of early cracks. Thus, it is important to extract vibration features due to breathing crack considering these two structures. Firstly, a blade with tenon and shroud is simplified and a lumped parameter model of the bladed disk is built. Then, dry friction and coupling force on a blade are analyzed and dynamics equations of the lumped parameter model are established. Next, the stiffness of the blade trunk with a breathing crack is analyzed. Finally, the vibration response of blade trunks with the occurrence of breathing crack is analyzed in time and frequency domains by numerical simulation. Effective features due to breathing crack for online identification are extracted. 2x components of spectrums can be the criterion to judge whether breathing crack occurs. Besides, by comparing the changes in vibration amplitudes with 1x component peaks of spectrums, the cracked blade trunk can be distinguished. These findings can provide important theoretical guidance for online identification of early cracks in aeroengine rotated blades.

Multi-Scale Account of Friction Heat and Heat Transfer in an Automotive Brake

2008 ◽  
Author(s):  
A. Elhomani ◽  
K. Farhang
Keyword(s):  
Mechanical Model ◽  
Lumped Parameter Model ◽  
Interface Temperature ◽  
Multi Scale ◽  
Disk Brake ◽  
System A ◽  
Surface Failure ◽  
Lumped Parameter ◽  
Thermal Capacitance ◽  
Automotive Brake

In applications involving substantial friction, surface failure is an inevitable phenomenon. Friction induced failure typically involves the generation of considerable heat. Existence of significant frictional force leads to relatively high interface temperature as a result of dynamic nature of flash temperatures at the contact areas. A first step in predicting friction induced failure is to develop an accurate thermo-mechanical model of the friction system. A 3D thermo-mechanical model is developed in this paper based on a lumped parameter representation of a two-disk brake. A disk is viewed as consisting of three main regions, (1) the surface contact, (2) the friction interface, and (3) the bulk. The 3D lumped parameter model is obtained by dividing a disk into a number of sub-sectors, adjacent sectors, and stacked layers. The friction layer contains both the interface and contact elements, each include the equivalent thermal capacitance and conductive resistance. The contact capacitance and resistance are described in terms of the elastic contact interaction between the surfaces of the two disks. Therefore they are obtained using the Greenwood and Williamson model for contact of rough surfaces. Each is described as a statistical summation of the micron-scale interaction of the surfaces.

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