Estimation for normal contact stiffness of joint surfaces by considering the variation of critical deformation

2020 ◽  
Vol 40 (3) ◽  
pp. 399-406
Author(s):  
Qingchao Sun ◽  
Xin Liu ◽  
Xiaokai Mu ◽  
Yichao Gao

Purpose This paper aims to study the relationship between normal contact stiffness and contact load. It purpose a new calculation model of the normal contact stiffness of joint surfaces by considering the elastic–plastic critical deformation change of asperities contact. Design/methodology/approach The paper described the surface topography of joint surfaces based on fractal geometry, and fractal parameters and of fractal function derived from measurement data. According to the plastic–elastic contact theory, the contact deformation characteristic of asperities was analyzed; the critical deformation estimation model was presented, which expressed critical deformation as the function of fractal parameters and contact deformation; the contact stiffness calculation model of single asperity was brought forward by considering critical deformation change. Findings The paper combined the surface topography description function, analyzed the asperity contact states by considering the critical deformation change, and calculated normal contact stiffness based on fractal theory and contact deformation analysis. The comparison between theoretical contact stiffness and experimental data indicated that the theoretical normal contact stiffness agreed with the experimental data, and the estimation model for normal contact stiffness was appropriate. Research limitations/implications Owing to the possibility of plastic deformation during the loading process, the experimental curve between the contact stiffness and the contact load is nonlinear, resulting in an error between the experimental results and the theoretical calculation results. Originality/value The paper established the relationship between critical deformation and fractal surface topography by constructing asperity distribution function. The paper proposed a new normal contact stiffness calculation model of joint surfaces by considering the variation of critical deformation in contact process.

Author(s):  
Yongquan Zhang ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
He Ling ◽  
Wei Fan ◽  
...  

Considering the rough surface as a fractal model makes the research of contact parameters more practical. In the fractal model of the machined surface, the parameters describing the surface topography are independent of the measurement resolution. Based on the elastic, elasto-plastic and plastic deformations of a single pair of contact asperities, a normal contact stiffness model using the fractal model for surface topography description is proposed in this paper. The specimens machined by milling and grinding methods are used to verify the proposed contact stiffness model based on the fractal theory. The experimental and theoretical results indicate that the proposed contact stiffness model is appropriate for the machined joint surfaces.


2020 ◽  
Author(s):  
Chao-Chao Yin ◽  
Hai-Hong Huang ◽  
Dan Zhou ◽  
Zhi-Feng Liu

Abstract Effects of surface texturing on the normal contact stiffness of joint surfaces had been investigated by experiments in many previous researches; however, there are relatively few theoretical models in this regard. The rough surface with surface texturing can be divided into two parts: the textured zone and the remaining zone, and their theoretical models are established respectively in this research. For the textured zone, the texture is modeled theoretically based on the three-dimensional topographic data obtained via a 3D-CCMP1 type laser profilometer from TRIMOS. For the remaining zone, the model of normal contact stiffness is established based on the fractal theory for the surface topography description and elastic-plastic deformation of surface asperities, and the structure function method is used to calculate the fractal dimension of rough surface profiles. In the experiment, the normal contact stiffness of specimens is obtained under different normal loads, and the test results are compared with the theoretical predictions. The result shows that the predictions of proposed theoretical model are in good agreement with the experimental data. For the joint surfaces with Sa>2.69 μm, the normal contact stiffness can be effectively increased through proper surface texturing.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nanshan Wang ◽  
Heng Liu ◽  
Yi Liu

Purpose The purpose of this study is to develop a normal contact stiffness (NCS) model among three disks of the assembled rotor system, which systematically considers the friction coefficient, the asperities interaction and the elastoplastic contact regime. Design/methodology/approach Based on the revised fractal theory, considering the friction effect, the elastoplastic contact regime and the asperities interaction in a simple way, the total NCS among three disks of the rod-fastening rotor bearing system is established. Effects of fractal dimension and roughness, friction coefficient, asperities interaction and material properties on the normal stiffness are investigated by simulations and the relevant comparisons are given for examining the reasonability of the proposed model. Findings NCS will decrease when asperities interaction and friction are included. As the load increases, the influences of asperities interaction and friction on stiffness become serious. NCS will be enhanced when the elastoplastic regime is considered. Originality/value A comprehensive NCS model is developed. It provides a theoretical basis for the modeling of the NCS for multi-interfaces.


2021 ◽  
Author(s):  
Chaochao Yin ◽  
Haihong Huang ◽  
Dan Zhou ◽  
Zhifeng Liu

Abstract Effects of surface texturing on the normal contact stiffness of joint surfaces had been investigated by experiments in many previous researches; however, there are relatively few theoretical models in this regard. The rough surface with surface texturing can be divided into two parts: the textured zone and the remaining zone, and their theoretical models are established respectively in this research considering surface morphology and material properties. For the textured zone, micro textures are modeled theoretically based on the three-dimensional topographic data obtained via a VK-X250 type laser profilometer from KEYENCE. For the remaining zone, the model of normal contact stiffness is established based on the fractal theory for the surface topography description and elastoplastic deformation of surface asperities, and the structure function method is used to calculate the fractal dimension of rough surface profiles. In the experiment, the normal contact stiffness of specimens is obtained under different normal loads, and the test results are compared with the theoretical predictions. The result shows that the predictions of proposed theoretical model are in good agreement with the experimental data. For the joint surfaces with Sa > 2.69 μm, the normal contact stiffness can be effectively increased through proper surface texturing.


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