Normal Contact Stiffness on Unit Area of a Mechanical Joint Surface Considering Perfectly Elastic Elliptical Asperities

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
J. P. Shi ◽  
K. Ma ◽  
Z. Q. Liu
Keyword(s):  
Contact Area ◽  
Unit Area ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Unit Length ◽  
Joint Surface ◽  
Normal Contact ◽  
Mechanical Joint ◽  
Normal Contact Stiffness ◽  
The Relationship

Based on the Greenwood and Williamson theory, an assumption about the contact-area size of asperities on rough surfaces is proposed under the premise that the height of these asperities on rough surfaces is a Gaussian distribution. A formula has been derived to measure the number of asperities on 2D surfaces. The contact stiffness on a unit length of a 1D outline and that on a unit area of 2D surfaces are presented based on a formula for determining the number of asperities. The relationship between macro parameters, such as contact stiffness and micro parameters on the joint surface, is established.

Normal Contact Stiffness Fractal Geometric Model Based on the Gamma Distribution of Rough Joint Surface

2013 ◽  
Vol 760-762 ◽  
pp. 2064-2067 ◽  
Author(s):  
Jing Fang Shen ◽  
Ke Xiang Wu ◽  
Fei Yang
Keyword(s):  
Convex Body ◽  
Gamma Distribution ◽  
Contact Stiffness ◽  
Geometric Model ◽  
Fractal Theory ◽  
Fractal Model ◽  
Joint Surface ◽  
Engineering Practice ◽  
Normal Contact ◽  
Normal Contact Stiffness

In this article, according to WenShuHua and Zhangxueniang fractal model, we point out the deficiency. Based on the fractal theory and Zhang, Wens contact stiffness fractal model, this paper puts forward Gamma distribution of rough joint surface normal contact stiffness. This paper considers micro convex body for ellipsoid, contact area for elliptic. This is slightly convex body for sphere hypothesis is more close to the actual situation. At the same time by using statistics theory, considering the contact ellipse long, short axis a and b are greater than zero, the assumption of a and b to two-dimensional Gamma distribution, it is more suitable for engineering practice.

Measurement and Modeling of Normal Contact Stiffness and Contact Damping at the Meso Scale

2005 ◽  
Vol 127 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Xi Shi ◽  
Andreas A. Polycarpou
Keyword(s):  
Wear Debris ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Damping Ratio ◽  
Minute Amount ◽  
Normal Contact ◽  
Flat Surfaces ◽  
Normal Contact Stiffness ◽  
Contact Parameters ◽  
Meso Scale

Modeling of contact interfaces that inherently include roughness such as joints, clamping devices, and robotic contacts, is very important in many engineering applications. Accurate modeling of such devices requires knowledge of contact parameters such as contact stiffness and contact damping, which are not readily available. In this paper, an experimental method based on contact resonance is developed to extract the contact parameters of realistic rough surfaces under lightly loaded conditions. Both Hertzian spherical contacts and flat rough surfaces in contact under normal loads of up to 1000 mN were studied. Due to roughness, measured contact stiffness values are significantly lower than theoretical values predicted from smooth surfaces in contact. Also, the measured values favorably compare with theoretical values based on both Hertzian and rough contact surfaces. Contact damping ratio values were found to decrease with increasing contact load for both Hertzian and flat surfaces. Furthermore, Hertzian contacts have larger damping compared to rough flat surfaces, which also agrees with the literature. The presence of minute amount of lubricant and wear debris at the interface was also investigated. It was found that both lubricant and wear debris decrease the contact stiffness significantly though only the lubricant significantly increases the damping.

scholarly journals Statistical Model of Normal Contact Stiffness of Fixed Joint Surface during Unloading after First Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Donghua Yin ◽  
Xueliang Zhang ◽  
Yonghui Chen ◽  
Guosheng Lan ◽  
Yanhui Wang ◽  
...  
Keyword(s):  
Statistical Model ◽  
Statistical Method ◽  
Contact Stiffness ◽  
Nonlinear Function ◽  
Joint Surface ◽  
Normal Contact ◽  
Surface Separation ◽  
Normal Contact Stiffness ◽  
Loading And Unloading ◽  
Simulation Results

Based on Kogut and Etsion’s model (KE model), a statistical method is used to establish a model of normal contact stiffness of fixed joint surface during unloading after first loading. Simulation results show that, for the elastoplastic contact, normal contact stiffness of joint surface is the nonlinear function of mean surface separation during loading and unloading and decreases as the separation increases. For different plasticity indexes, the normal contact stiffness of joint surface varies differently following the change of mean surface separation during loading and unloading.

Numerical Analysis of Normal Contact Stiffness of Rough Surfaces

2016 ◽  
Vol 846 ◽  
pp. 300-305
Author(s):  
Chong Pu Zhai ◽  
Yi Xiang Gan ◽  
Dorian Hanaor
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Normal Load ◽  
Contact Stiffness ◽  
Surface Characterisation ◽  
Small Surface ◽  
Normal Contact ◽  
Contact Behaviour ◽  
Normal Contact Stiffness ◽  
Stress Dependent

A numerical model was proposed to investigate the contact behaviour of a solid with a rough surface squeezed against a rigid flat plane. We considered simulated hierarchical surface structures as well as scanned surface data obtained by the profilometry of isotropically roughened specimens. The simulated and treated surfaces were characterised using statistical and fractal parameters. The evolution of contact stiffness under increasing normal compression was analysed through the total truncated area at varying heights, in order to relate contact mechanics to different surface parameters employed for surface characterisation. For a relatively small surface interference, the predicted stress-dependent normal contact stiffness of both scanned and simulated surfaces is in good agreement with experimental observation from nanoindentation tests, revealing a power-law function of the normal load, with the exponent of this relationship closely depending on the fractal dimension of rough surfaces. The numerical results show that the amplitude of a fractal rough surface mainly contributes to the magnitude of the contact stiffness at a given normal load.

A Contact Mechanics Model for Rough Surfaces Based on a New Fractal Characterization Method

2018 ◽  
Vol 10 (06) ◽  
pp. 1850069 ◽  
Author(s):  
Jianjun Sun ◽  
Zhengbo Ji ◽  
Yuyan Zhang ◽  
Qiuping Yu ◽  
Chenbo Ma
Keyword(s):  
Contact Mechanics ◽  
Rough Surface ◽  
Contact Pressure ◽  
Contact Area ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Measurement Scale ◽  
Real Contact Area ◽  
Sample Length ◽  
Normal Contact

There are mainly two kinds of contact mechanics models for rough surfaces. One is based on the statistical characteristic parameters and depends on the measurement scale of rough surface topography. The other is based on the fractal parameters, which is independent of the measurement scale. However, most of the contact models for rough surfaces based on fractal theory use the size that is corresponding to the contact area of an asperity or the sample length as the base diameter of an asperity to describe the initial profile of asperities. As a result, the obtained deformation mechanism of asperities is not correct. To solve this problem, a new fractal characterization method for rough surfaces based on the fractal dimension [Formula: see text], fractal roughness [Formula: see text] and the highest asperity height is proposed, and then a fractal contact model independent of the measurement scale is established. The contact mechanism of asperities and variation trends of the real contact area and contact stiffness are discussed. When the contact pressure of the rough surface is less than its yield strength, its normal contact stiffness can be expressed as the first derivative of the contact pressure versus the normal compression, regardless of the deformation forms of asperities.

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