scholarly journals A Novel Micro-Contact Stiffness Model for the Grinding Surfaces of Steel Materials Based on Cosine Curve-Shaped Asperities

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3561
Author(s):  
Qi An ◽  
Shuangfu Suo ◽  
Fuyan Lin ◽  
Jianwen Shi
Keyword(s):  
Rough Surface ◽  
Contact Pressure ◽  
Present Model ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Experimental Results ◽  
Cosine Curve ◽  
Steel Material ◽  
Comparison Results ◽  
Stiffness Model

Contact stiffness is an important parameter for describing the contact behavior of rough surfaces. In this study, to more accurately describe the contact stiffness between grinding surfaces of steel materials, a novel microcontact stiffness model is proposed. In this model, the novel cosine curve-shaped asperity and the conventional Gauss distribution are used to develop a simulated rough surface. Based on this simulated rough surface, the analytical expression of the microcontact stiffness model is obtained using contact mechanics theory and statistical theory. Finally, an experimental study of the contact stiffness of rough surfaces was conducted on different steel materials of various levels of roughness. The comparison results reveal that the prediction results of the present model show the same trend as that of the experimental results; the contact stiffness increases with increasing contact pressure. Under the same contact pressure, the present model is closer to the experimental results than the already existing elastic–plastic contact (CEB) and finite-element microcontact stiffness (KE) models, whose hypothesis of a single asperity is hemispherical. In addition, under the same contact pressure, the contact stiffness of the same steel material decreases with increasing roughness, whereas the contact stiffness values of different steel materials under the same roughness show only small differences. The correctness and accuracy of the present model can be demonstrated by analyzing the measured asperity geometry of steel materials and experimental results.

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.

Stiffness model of fixed joint considering self-affinity and elastoplasticity of asperities

2019 ◽  
Vol 72 (1) ◽  
pp. 128-135 ◽  
Author(s):  
Hongxu Chen ◽  
Qin Yin ◽  
Guanhua Dong ◽  
Luofeng Xie ◽  
Guofu Yin
Keyword(s):  
Elastic Deformation ◽  
Contact Stiffness ◽  
Roughness Parameter ◽  
Experimental Results ◽  
Content Type ◽  
Elastoplastic Contact ◽  
Proposed Model ◽  
Stiffness Model ◽  
Fractal Roughness ◽  
Deformation Ratio

Purpose The purpose of this paper is to establish a stiffness model of fixed joint considering self-affinity and elastoplasticity of asperities. Design/methodology/approach The proposed model considers that asperities of different scales are interrelated rather than independent. For elastoplastic contact, a spring-damper model and an elastic deformation ratio function were proposed to calculate the contact stiffness of asperities. Findings A revised fractal asperity model was proposed to calculate the contact stiffness of fixed joint, the impacts of the fractal dimension, the fractal roughness parameter and the Meyer index on the contact stiffness were discussed, and the present experimental results and the Jiang’s experimental results showed that the stiffness can be well predicted by proposed model. Originality/value The contradiction between the Majumdar and Bhushan model and the Morag and Etsion model can be well explained by considering the interaction among asperities of different scales. For elastoplastic contact, elastic deformation ratio should be considered, and the stiffness of asperities increases first and then decreases with the increasing of interference.

scholarly journals Comparison of experimental and theoretical results of airflow around two rough surfaces at different speeds

2021 ◽  
Vol 2127 (1) ◽  
pp. 012020
Author(s):  
Win Thu ◽  
D V Ilin ◽  
N M Skornyakova
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Experimental Results ◽  
System Of Equations ◽  
Theoretical Results

Abstract The aim of the work is to determine the effect of a rough surface on the airflow flowing around it, depending on the degree of roughness of this surface. Experimental visualization of the flow of air around samples with various rough surfaces is carried out. The experimental results are compared with the theoretical results obtained as a result of modeling this process based on the RANS system of equations.

A statistical model of elastic-plastic contact between rough surfaces

2019 ◽  
Vol 43 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Guang Zhao ◽  
Sheng-xiang Li ◽  
Zhi-liang Xiong ◽  
Wen-dong Gao ◽  
Qing-kai Han
Keyword(s):  
Plastic Deformation ◽  
Interface Design ◽  
Present Model ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Contact Point ◽  
Contact Model ◽  
Elastic Plastic ◽  
Classical Models ◽  
Asperity Deformation

In a mechanical interface, the contact surface topography has an important influence on the contact stiffness. In the contact processes of asperities, elastic-plastic change can lead to discontinuity and lack of smoothness at a critical contact point. The result is a large difference between the elastic-plastic deformation and the actual asperity deformation. Based on Hertz contact theory, the heights of asperities on a rough surface obey a Gaussian distribution. To take into consideration the continuity of elastic-plastic asperity deformation, we divide the elastic-plastic deformation into three stages: pre-elastic-plastic, mid-elastic-plastic, and post-elastic-plastic deformation. This establishes an elastic-plastic contact model of asperity at a continuous critical point. The contact model of a single asperity fits well with the Kogut–Etsion model and the Zhao–Maietta–Chang model, and the variation trend is consistent. At a lower plastic index, the present model coincides with classical models of contact area and contact load. At a higher plastic index, the simulation results of the present model differ from the Greenwood–Williamson model and the Chang–Etsion–Bogy model but are similar to results from the Kogut–Etsion and Zhao–Maietta–Chang models. This study provides a more accurate microscopic contact model for rough surfaces and a theoretical framework for interface design and analysis.

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 Stiffness Model of Machined Plane Joint Based on Fractal Theory

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Shuyun Jiang ◽  
Yunjian Zheng ◽  
Hua Zhu
Keyword(s):  
Contact Stiffness ◽  
Fractal Theory ◽  
Fractal Model ◽  
Experimental Results ◽  
Size Dependent ◽  
Contact Loads ◽  
Proposed Model ◽  
Stiffness Model ◽  
Surface Profiles ◽  
Plane Joint

A general contact stiffness model is proposed in this paper to study the contacts between rough surfaces of machined plane joints. The proposed model uses fractal geometry for surface topography description, elastic-plastic deformation of contacting asperities, and size-dependent contact stiffness of microcontacts, where the contact stiffness is derived from Hertz contact theory. Three cast iron specimens are produced from different machining methods (milling, grinding, and scraping), and their rough surface profiles are extracted. The structure function method was used to calculate each profile’s fractal dimension and scale coefficient. Both theoretical analysis and experimental results of contact stiffness are obtained for these specimens under different contact loads. The comparison between the theoretical contact stiffness and the experimental results at the interface indicates that the present fractal model for the contact stiffness is appropriate and the theoretical contact stiffness is consistent with the experimental data.

Analysis of Normal Elastic Contact Stiffness of Rough Surfaces Based on Ubiquitiform Theory

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Shaofei Shang ◽  
Xiaoshan Cao ◽  
Zhiqiang Liu ◽  
Junping Shi
Keyword(s):  
Lower Bound ◽  
Rough Surface ◽  
Scale Invariance ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Elastic Contact ◽  
Normal Contact ◽  
Normal Stiffness ◽  
Normal Contact Stiffness ◽  
The Impact

Abstract In this study, the normal stiffness of elastic contact between rough surfaces with asperities following Gaussian distribution is investigated using ubiquitiform theory, developed from fractal theory. In the generalized ubiquitiformal Sierpinski carpet model, the rough surface including contact asperity is controlled for, given the lower bound to scale invariance of rough surfaces. Considering the stiffness of a single asperity deduced from the Hertz contact model, we deduce the theoretical relation between the normal stiffness and the elastic contact of rough surfaces based on ubiquitiform theory. The results show that the normal contact stiffness of a rough surface increases as the normal load rises. If the ubiquitiformal complexity of a rough surface increases or the lower bound to scale invariance of a rough surface decreases, the normal contact stiffness of the rough surface should increase. The larger the ubiquitiformal complexity of a rough surface is, the more obvious the impact of the lower bound to scale invariance on the normal contact stiffness of the rough surface becomes. The results based on the ubiquitiformal model and the experimental results are in closer agreement. Therefore, the introduction of scale invariance is crucial to the surface contact problem.

scholarly journals Insights into the Multilevel Structural Characterization and Adsorption Mechanism of Sinogastromyzon szechuanensis Sucker on the Rough Surface

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 952
Author(s):  
Qian Cong ◽  
Jin Xu ◽  
Jiaxiang Fan ◽  
Tingkun Chen ◽  
Shaofeng Ru
Keyword(s):  
Surface Roughness ◽  
Spectral Function ◽  
Rough Surface ◽  
Structural Characterization ◽  
Adsorption Mechanism ◽  
Rough Surfaces ◽  
Experimental Results ◽  
Adsorption Performance ◽  
Multilevel Structure ◽  
New Type

The present study investigates the adsorption performance and adsorption mechanism of Sinogastromyzon szechuanensis on different rough surfaces. The different positions of the sucker surface of Sinogastromyzon szechuanensis were observed by adopting the stereomicroscope and SEM. The observed results showed that the sucker of Sinogastromyzonszechuanensis had a multilevel structure of villi and groove. The anterior and posterior of Sinogastromyzonszechuanensis had different microscopic morphologies. The surface roughness of the adsorption substrate ranged from 7 μm to 188 μm. Adsorption strength of Sinogastromyzonszechuanensis and the conventional sucker on different rough surfaces were measured by a purposely designed device. The results showed that the back of Sinogastromyzonszechuanensis mainly provided the adsorption strength. The adsorption strength of the conventional sucker gradually decreased with surface roughness increasing, but the adsorption strength of Sinogastromyzon szechuanensis had not changed significantly. Based on the experimental results, the adsorption mechanism of Sinogastromyzonszechuanensis on the surface with different roughness was analyzed by the spectral function. The Sinogastromyzonszechuanensis sucker with a multilevel structure worked well on the rough surface, which led to Sinogastromyzonszechuanensis with a good sealing on the rough surface. The present work could help to develop a new type of sucker with effective adsorption performance on a rough surface to meet the needs of the engineering field.

A realistic model for transverse shear stiffness prediction of composite corrugated-core sandwich structure with bonding effect

2021 ◽  
pp. 109963622199386
Author(s):  
Tianshu Wang ◽  
Licheng Guo
Keyword(s):  
Present Model ◽  
Shear Stiffness ◽  
Realistic Model ◽  
Torsional Stiffness ◽  
Fem Model ◽  
The Core ◽  
Bonding Effect ◽  
Stiffness Model ◽  
Bonding Area ◽  
The Relationship

In this paper, a shear stiffness model for corrugated-core sandwich structures is proposed. The bonding area is discussed independently. The core is thought to be hinged on the skins with torsional stiffness. The analytical model was verified by FEM solution. Compared with the previous studies, the new model can predict the valley point of the shear stiffness at which the relationship between the shear stiffness and the angle of the core changes from negative correlation to positive correlation. The valley point increases when the core becomes stronger. For the structure with a angle of the core smaller than counterpart for the valley point, the existing analytical formulations may significantly underestimate the shear stiffness of the structure with strong skins. The results obtained by some previous models may be only 10 persent of that of the present model, which is supported by the FEM model.

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