Modeling of Frictional Stick-Slip of Contact Interfaces Considering Normal Fractal Contact

2021 ◽  
pp. 1-19
Author(s):  
Kai Zong ◽  
Zhaoye Qin ◽  
Fulei Chu
Keyword(s):  
Surface Topography ◽  
Contact Surface ◽  
Mechanical Characteristics ◽  
Contact Spot ◽  
Physical Significance ◽  
Experimental Setup ◽  
Stick Slip ◽  
Normal Loading ◽  
Modeling Approach ◽  
Distribution Principle

Abstract In this paper, a physics-based approach is proposed to represent the tangential frictional stick-slip behaviors of contact interfaces in mechanical systems. The modeling idea of the discrete Iwan model is adopted, where the yield forces of Jenkins elements are determined by considering the surface fractal feature and normal loading conditions. Initially, surrogate asperities are defined to express the fractal features of the contact surface topography, and Jenkins elements are used to describe the tangential stick-slip motions between surrogate contact asperities. Then, a geometric series distribution principle of the normal loads at contact asperities is proposed to determine the yield forces of the Jenkins elements. The criterion for identifying the micro- and macro-slips of the contact interfaces is proposed, which are determined by the stick and slip conditions of the largest contact spot. An experimental setup for measuring frictional stick-slip of contact interfaces was constructed, upon which tangential quasi-static experiments were conducted. Satisfactory agreements between the theoretical and experimental results indicates that the proposed modeling approach can perfectly predict the stick-slip behavior of the contact interfaces. Finally, mechanical characteristics of the contact interfaces were investigated in detail by employing the validated modeling approach. Owing to the definite physical significance of the proposed modeling approach, the mechanism of the tangential stick-slip behavior of contact interfaces is partially demonstrated.

The effects of grooved rubber blocks on stick–slip and wear behaviours

2018 ◽  
Vol 233 (11) ◽  
pp. 2939-2954 ◽  
Author(s):  
Xiao Cui Wang ◽  
Ji Liang Mo ◽  
Huajiang Ouyang ◽  
Xiao Dong Lu ◽  
Bo Huang ◽  
...  
Keyword(s):  
Relative Velocity ◽  
Surface Modifications ◽  
Experimental Results ◽  
Brake Disc ◽  
Experimental Setup ◽  
Brake Pad ◽  
Stick Slip ◽  
Elastic Rubber ◽  
Disc Configuration ◽  
Rubber Block

This work presents an experimental and theoretical combined study of the effects of the elastic rubber blocks with different surface modifications on the friction-induced stick–slip oscillation and wear of a brake pad sample in sliding contact with an automobile brake disc. The experiments are conducted on the customized experimental setup in a pad-on-disc configuration. The experimental results show that (1) the friction system with the plain rubber block still exhibits visible stick–slip oscillation, but the intensity of the stick–slip oscillation is reduced to a certain degree compared with the Original friction system (without rubber block); (2) the grooved rubber blocks display a better ability to reduce the stick–slip oscillation compared with the plain rubber block; (3) the rubber blocks with a vertical groove (perpendicular to the relative velocity) or a horizontal groove (parallel to the relative velocity) or a diagonal groove (45° inclined to the relative velocity) on their surfaces can suppress the stick–slip oscillation more effectively with various degrees of success. The experimental results also reveal the varying effects of the different rubber blocks on wear. To explain the experimental phenomenon reasonably, a theoretical analysis is conducted to investigate the effects of different rubber blocks on both stick–slip oscillation and wear using ABAQUS. Furthermore, the analysis of the contact pressure on the pad interfaces and the deformation of the rubber blocks are studied to provide a possible explanation of the experimental results.

Dynamic characterization of Portevin–Le Chatelier instabilities occurring in depth-sensing microhardness tests

2003 ◽  
Vol 18 (12) ◽  
pp. 2874-2881 ◽  
Author(s):  
G. Bérces ◽  
J. Lendvai ◽  
A. Juhász ◽  
N.Q. Chinh
Keyword(s):  
Dynamic Model ◽  
Contact Surface ◽  
Indentation Depth ◽  
Loading Rate ◽  
Experimental Setup ◽  
Dynamic Characterization ◽  
Depth Sensing ◽  
Constant Loading ◽  
Constant Loading Rate

Characteristic properties of plastic instabilities were studied using depth-sensing microhardness experiments on an Al–3.3 wt.% Mg alloy and computer simulations based on a macroscopic dynamic model of the experimental setup. A stepwise increase was observed in the indentation depth versus load (d-F) curves measured in constant loading rate mode, indicating hardness oscillations around a nearly constant value of the conventional dynamic microhardness. These oscillations were correlated with plastic instabilities starting from the contact surface between the sample and the indenter head. Taking into account the experimentally determined connection between the hardness oscillations and the indentation velocity, a dynamic model was proposed for the characterization of instability steps.

Simulation Study of the Grinding Process

1973 ◽  
Vol 95 (4) ◽  
pp. 972-978 ◽  
Author(s):  
S. S. Law ◽  
S. M. Wu
Keyword(s):  
Surface Topography ◽  
Simulation Study ◽  
Digital Computer ◽  
Surface Interactions ◽  
Apex Angle ◽  
Physical Significance ◽  
Depth Of Cut ◽  
Grinding Process ◽  
Stochastic Nature ◽  
Table Speed

A model in terms of grain distributions and kinematic conditions has been recently developed [8] for a specified grinding process. Using this model, an exploratory attempt was made to study the grinding process with respect to the surface topography and nature of surface interactions by simulation on a digital computer. Fundamental grinding parameters, such as the effective grain density, grain spacings, chip depths, and chip areas, are employed to describe the grain-workpiece interactions. The grinding process is studied under a systematic variation of table speed, wheel depth of cut, and grain apex angle. The physical significance of the Z-distribution and stochastic nature of the grinding process is also discussed.

A Surface Connectivity-Based Approach for Leakage Channel Prediction in Static Sealing Interface

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Yiping Shao ◽  
Yaxiang Yin ◽  
Shichang Du ◽  
Lifeng Xi
Keyword(s):  
Surface Topography ◽  
Contact Surface ◽  
Three Dimensional ◽  
Surface Generation ◽  
Prediction Algorithm ◽  
High Definition ◽  
Spatial Connectivity ◽  
Channel Prediction ◽  
Sealing Performance ◽  
Correlation Parameters

Leakage susceptibility is significant for the functionalization of engineering products, and surface topography plays a crucial role in forming the leakage channel in static sealing interface. This paper proposes a surface connectivity-based approach to predict the leakage channel in static sealing interface. The proposed approach consists of three modules including contact surface generation, leakage parameters definition, and leakage channel prediction. A high-definition metrology (HDM) instrument is adopted to measure the three-dimensional (3D) surface. The contact surface that can be considered as the sealing interface is generated by assembling the virtual gasket surface and waviness surface. Considering the spatial connectivity, two kinds of leakage parameters including connectivity parameters and correlation parameters are proposed to describe the characteristics of the contact surface. Meantime, a novel prediction algorithm is developed to directly indicate the potential leakage channel of the surface. Experimental results demonstrate that the proposed approach is valid to be accurate and effective, which can provide valuable information for surface topography and static sealing performance.

Effects of Pad Surface Topography on Disc Brake Squeal

2012 ◽  
Vol 165 ◽  
pp. 58-62 ◽  
Author(s):  
Ahmad Razimi Mat Lazim ◽  
Mohd Kameil Abdul Hamid ◽  
Abd Rahim Abu Bakar
Keyword(s):  
Surface Topography ◽  
Optical Microscope ◽  
Frequency Noise ◽  
Brake Pad ◽  
Brake Squeal ◽  
Stick Slip ◽  
Disc Brakes ◽  
Brake Dynamometer ◽  
Warranty Claims ◽  
Microscopic Techniques

Brake squeal has always been a major NVH problem to many car makers due to significant number of warranty claims. Brake squeal is a high frequency noise (above 1 kHz) emanating from car disc brakes that get excited due to one or more mechanisms such as mode coupling, stick-slip, hammering and sprag-slip. This paper attempts to investigate the effects of brake pad surface topography on squeal generation. Two pairs of a non-asbestos organic (NAO) brake pad will be tested on a brake dynamometer test rig. Surface topography of the brake pad will be analyzed through microscopic techniques using energy dispersive X-ray analysis (EDX), and optical microscope.

Research Note: Reduction in Relaxation Oscillation (Stick-Slip) Amplitudes by Normal Excitation

1977 ◽  
Vol 19 (1) ◽  
pp. 42-44 ◽  
Author(s):  
J. B. Hunt
Keyword(s):  
Coefficient Of Friction ◽  
Contact Surface ◽  
Relaxation Oscillation ◽  
Research Note ◽  
Stick Slip ◽  
Resonant Frequencies ◽  
Maximum Value ◽  
The Coefficient Of Friction

When a slider-slideway system was excited by vibratory forces applied normally to the contact surface, it was found that at low sliding speeds the amplitude of stick-slip oscillation could be reduced to a negligible value. By exciting at one of the structural resonant frequencies of the system, the maximum value of the vibratory forces required was only a small percentage of the slideway load. The value of the coefficient of friction between the two surfaces was not reduced.

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