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.

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.

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.

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.

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.

scholarly journals Analytical modeling of the human cardiovascular system with real-time implementation using NI ELVIS-II

2018 ◽  
Vol 7 (3.3) ◽  
pp. 628
Author(s):  
Sisir Chettri ◽  
Akash Kumar Bhoi ◽  
Gyoo Soo Chae ◽  
Nilas Gurung ◽  
Ashis Sharma
Keyword(s):  
Cardiovascular System ◽  
Real Time ◽  
Human Body ◽  
Blood Circulation ◽  
Lumped Parameter Model ◽  
Blood Flows ◽  
System A ◽  
Lumped Parameter ◽  
Electrical Analogy ◽  
Human Cardiovascular System

Cardiovascular System, which consists of the heart, the systematic circulation and the pulmonary circulation is said to be the transport system for the human body. Modeling of cardiovascular system has become important for clinical researchers and for deeper understanding of blood circulation in the human body. This paper uses the lumped method which is also known as an electrical analogy for modeling and simulation of human cardiovascular system. A simplified complete lumped parameter model of the Human Cardiovascular System has been developed with real time implementation focusing mainly on blood flows. A resistor, an inductor and a capacitor are used to model every blood vessel, ventricles, atrium and set of all veins and capillaries. A pulse generating circuit is also modeled which acts as a power supply for the heart that controls the contraction of heart muscles.   

scholarly journals Refrigerant selection for ejector refrigeration systems: a multiscale evaluation

2020 ◽  
Vol 197 ◽  
pp. 10011
Author(s):  
Giorgio Besagni ◽  
Lorenzo Croci ◽  
Nicolò Cristiani ◽  
Gaël Raymond Guédon ◽  
Fabio Inzoli
Keyword(s):  
Fluid Dynamic ◽  
Lumped Parameter Model ◽  
Local Flow ◽  
Multi Scale ◽  
Lumped Parameter ◽  
Flow Phenomena ◽  
Phase Out ◽  
Scale Challenges ◽  
Dynamic Phenomena ◽  
Selection Of

The selection of refrigerants for ejector refrigeration systems, within the broader discussion concerning refrigerant phase-out, is a cutting-edge and challenging research topic, owing to the multi-scale challenges in ejector performance. Indeed, it is known that the performances of ejector refrigeration systems depend on the local flow phenomena. For this reason, a precise selection of the refrigerant relies on the understanding of the fluid dynamic phenomena at the “componentscale”, and integrate such information within the so-called “system-scale”. This paper contributes to the current discussion proposing a screening of refrigerants based on an integrated Computational Fluid Dynamic (CFD) Lumped Parameter Model (LPM) approach. In this approach, ejector performances for the different refrigerant are obtained by a validated CFD approach, whereas the cycle is modelled by a Lumped Parameter Model. For the different refrigerants, the energy performances of the systems are evaluated and the effects of the “component-scale” on the “system-scale” are analysed.

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