Analysis of out-of-plane motion of a disc brake system using a two-degree-of-freedom model with contact stiffness

2005 ◽  
Vol 219 (7) ◽  
pp. 869-879 ◽  
Author(s):  
J-E Oh ◽  
Y-G Joe ◽  
K Shin
Keyword(s):  
Friction Coefficient ◽  
Relative Velocity ◽  
Normal Force ◽  
Contact Stiffness ◽  
Plane Motion ◽  
Degree Of Freedom ◽  
Brake System ◽  
Disc Brake ◽  
Out Of Plane ◽  
Two Degree Of Freedom

A two-degree-of-freedom out-of-plane model with contact stiffness is presented to describe dynamic interaction between the pad and disc of a disc brake system. It is assumed that the out-of-plane motion of the system depends on the friction force acting along the in-plane direction. The dynamic friction coefficient is modelled as a function of both in-plane relative velocity and out-of-plane normal force. When the friction coefficient depends only on the relative velocity, the contact stiffness has the role of negative stiffness. The results of stability analysis show that the stiffnesses of the pad and disc are equally important. Complex eigenvalue analysis is conducted for the case where the friction coefficient is also dependent on the normal force. The results further verify the importance of the stiffness. It has also been found that increasing the gradient of the friction coefficient with respect to the normal force makes the system more unstable. Non-linear analysis is also performed to demonstrate various responses. Comparing the responses with experimental data has shown that the proposed model may qualitatively well represent a certain type of brake noise.

scholarly journals Three-dimensional CFD modeling of thermal behavior of a disc brake and pad for an automobile

2020 ◽  
Vol 15 (4) ◽  
pp. 543-549
Author(s):  
Haydar Kepekci ◽  
Ergin Kosa ◽  
Cüneyt Ezgi ◽  
Ahmet Cihan
Keyword(s):  
Cast Iron ◽  
Friction Coefficient ◽  
Elevated Temperatures ◽  
Gray Cast Iron ◽  
Three Dimensional ◽  
Brake System ◽  
Gray Cast ◽  
Cfd Modeling ◽  
Disc Brake ◽  
Disc Material

Abstract The brake system of an automobile is composed of disc brake and pad which are co-working components in braking and accelerating. In the braking period, due to friction between the surface of the disc and pad, the thermal heat is generated. It should be avoided to reach elevated temperatures in disc and pad. It is focused on different disc materials that are gray cast iron and carbon ceramics, whereas pad is made up of a composite material. In this study, the CFD model of the brake system is analyzed to get a realistic approach in the amount of transferred heat. The amount of produced heat can be affected by some parameters such as velocity and friction coefficient. The results show that surface temperature for carbon-ceramic disc material can change between 290 and 650 K according to the friction coefficient and velocity in transient mode. Also, if the disc material gray cast iron is selected, it can change between 295 and 500 K. It is claimed that the amount of dissipated heat depends on the different heat transfer coefficient of gray cast iron and carbon ceramics.

SOFTENING BRANCHES OF A TWO-DEGREE-OF-FREEDOM SYSTEM INDUCED BY SPATIAL BUCKLING

2006 ◽  
Vol 06 (04) ◽  
pp. 493-512 ◽  
Author(s):  
NOËL CHALLAMEL
Keyword(s):  
Structural Model ◽  
Structural Parameters ◽  
Degree Of Freedom ◽  
Lateral Loading ◽  
Load Parameter ◽  
Imperfection Sensitivity ◽  
Softening Effect ◽  
Out Of Plane ◽  
Secondary Bifurcation ◽  
Two Degree Of Freedom

The aim of this paper is to show how geometrical non-linearity may induce equivalent softening in a simple two-degree-of-freedom spatial elastic system. The generic structural model studied is a generalization of Augusti's spatial model, incorporating lateral loading. This model could be used as a teaching model to understand the softening effect induced by out-of-plane buckling. The lateral loading in the plane of maximal stiffness is considered as the varying load parameter, whereas the vertical load is perceived as a constant parameter. It is shown that a bifurcation occurs at the critical horizontal load. The fundamental path becomes unstable, beyond this critical value. However, two symmetrical bifurcate solutions appear, whose stability depend on the structural parameters value. No secondary bifurcation is observed for this system. The presented system possesses imperfection sensitivity, and imperfection insensitivity, depending on the values of the structural parameters. In any case, for sufficiently large rotations, collapse occurs with unstable softening branches induced by spatial buckling.

ANALYSIS OF DISC BRAKE NOISE USING A TWO-DEGREE-OF-FREEDOM MODEL

2002 ◽  
Vol 254 (5) ◽  
pp. 837-848 ◽  
Author(s):  
K. SHIN ◽  
M.J. BRENNAN ◽  
J.-E. OH ◽  
C.J. HARRIS
Keyword(s):  
Degree Of Freedom ◽  
Disc Brake ◽  
Brake Noise ◽  
Two Degree Of Freedom

Time-Frequency Analysis of Disc Brake Squeal in a Brake Experiment

2013 ◽  
Author(s):  
X. D. Liu ◽  
H. X. Wang ◽  
Z. S. Wan ◽  
Y. C. Shan
Keyword(s):  
Friction Coefficient ◽  
Dynamic Behavior ◽  
Frequency Analysis ◽  
Contact Stiffness ◽  
High Energy ◽  
Disc Brake ◽  
Brake Squeal ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Brake Pressure

Automotive brake squeal has become a challenging issue to reduce traffic noise and improve the vehicle quality. Since the generation mechanism of brake squeal is extremely complex, involving multiple disciplines such as nonlinear dynamics, contact mechanics, tribology and acoustics, it is still not well understood. The brake bench experiment is an important method to investigate the evolution of squeal and the transient nonlinear dynamic behavior of brake system, because of the difficulties in modeling the nonlinear time-varying system parameters in braking, such as friction coefficient, contact stiffness and damping in brake pads, for analytical and numerical method. Here a laboratory experiment is constructed to simulate vehicle disc brake squeal. The rotation speed, brake pressure, torque, temperature and sound pressure are measure during the braking process with squeal events. The variations of friction coefficient versus temperature and brake pressure are investigated respectively. It is obtained that the friction coefficient increases with the increasing temperature and brake pressure. The evolution of brake squeal and its transient dynamic behavior are analyzed and discussed through three time-frequency analysis methods including STFT, CWT and HHT. The results demonstrate that the squeal signal is composed of several frequency components and may be dominated by one or two components with high energy which are related to the vibration modes of physical brake parts. The instantaneous frequencies of IMFs vibrate substantially with time induced by the nonlinear friction and contact between the disc and pad pairs.

Analysis of High Frequency Squeal in a Disc-Brake System Using a Stick-Slip Friction Model

2003 ◽  
Author(s):  
Manish Paliwal ◽  
Ajay Mahajan ◽  
Peter Filip
Keyword(s):  
High Frequency ◽  
Contact Stiffness ◽  
Friction Model ◽  
System Stability ◽  
Disc Brake ◽  
Brake Pad ◽  
Stick Slip ◽  
Parametric Studies ◽  
The Stability ◽  
Two Degree Of Freedom

This paper presents a two degree of freedom (2-DOF) stick-slip friction model for studying the effect of contact stiffness on the stability of the system. It is shown that the stability is not only a function of non-linear variation in the friction force provide by stick-slip but also depends on the variation in stiffness of contact due to the formation of friction layers on the surface of the rotor and the brake pad. Parametric studies have been presented to show the effect of variation in coefficient of friction and contact stiffness on the system stability.

Stick-Slip Dynamics of a Two-Degree-of-Freedom System

2001 ◽  
Author(s):  
Jan Awrejcewicz ◽  
Pawel Olejnik
Keyword(s):  
Friction Coefficient ◽  
Autonomous System ◽  
Chaotic Dynamics ◽  
Degree Of Freedom ◽  
Discontinuous System ◽  
Stick Slip ◽  
Two Degree Of Freedom

Abstract Two-degree-of-freedom autonomous system with friction is analyzed numerically. The friction coefficient has been smoothened using are tan function. The standard, but slightly modified chaos identification tools have been applied for the analyzed discontinuous system. Some interesting examples of stick-slip regular and chaotic dynamics have been illustrated and discussed.

scholarly journals Two Degree-of-Freedom Fiber-Coupled Heterodyne Grating Interferometer with Milli-Radian Operating Range of Rotation

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3219 ◽  
Author(s):  
Fuzhong Yang ◽  
Ming Zhang ◽  
Yu Zhu ◽  
Weinan Ye ◽  
Leijie Wang ◽  
...  
Keyword(s):  
Angular Displacement ◽  
Reference Beam ◽  
Angular Position ◽  
Degree Of Freedom ◽  
Displacement Measurement ◽  
Operating Range ◽  
Out Of Plane ◽  
Grating Interferometer ◽  
To Receive ◽  
Two Degree Of Freedom

In the displacement measurement of the wafer stage in lithography machines, signal quality is affected by the relative angular position between the encoder head and the grating. In this study, a two-degree-of-freedom fiber-coupled heterodyne grating interferometer with large operating range of rotation is presented. Fibers without fiber couplers are utilized to receive the interference beams for high-contrast signals under the circumstances of large angular displacement and ZEMAX ray tracing software simulation and experimental validation have been carried out. Meanwhile, a reference beam generated inside the encoder head is adopted to suppress the thermal drift of the interferometer. Experimental results prove that the proposed grating interferometer could realize sub-nanometer displacement measurement stability in both in-plane and out-of-plane directions, which is 0.246 nm and 0.465 nm of 3σ value respectively within 30 s.

Sign in / Sign up

Export Citation Format

Share Document