scholarly journals Linear relationship of normal and tangential contact stiffness with load

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200329
Author(s):  
K. S. Parel ◽  
R. J. Paynter ◽  
D. Nowell
Keyword(s):  
Surface Roughness ◽  
Linear Relationship ◽  
Normal Load ◽  
Contact Stiffness ◽  
Roughness Parameter ◽  
Image Correlation ◽  
Tangential Load ◽  
Normal Contact ◽  
Tangential Contact ◽  
Normal Contact Stiffness

Measurements with digital image correlation of normal and tangential contact stiffness for ground Ti-6Al-4V interfaces suggest a linear relationship between normal contact stiffness and normal load and a linear relationship between tangential contact stiffness and tangential load. The normal contact stiffness is observed approximately to be inversely proportional to an equivalent surface roughness parameter, defined for two surfaces in contact. The ratio of the tangential contact stiffness to the normal contact stiffness at the start of tangential loading is seen to be given approximately by the Mindlin ratio. A simple empirical model is proposed to estimate both the normal and tangential contact stiffness at different loads for a ground Ti-6Al-4V interface, on the basis of the equivalent surface roughness and the coefficient of friction.

Analysis and Research on Fractal Model of Normal Contact Stiffness of Joint Interfaces

2011 ◽  
Vol 328-330 ◽  
pp. 336-345
Author(s):  
Guo Sheng Lan ◽  
Xue Liang Zhang ◽  
Hong Qin Ding ◽  
Shu Hua Wen ◽  
Zhong Yang Zhang
Keyword(s):  
Numerical Simulation ◽  
Fractal Dimension ◽  
Normal Load ◽  
Contact Stiffness ◽  
Fractal Model ◽  
Normal Contact ◽  
Fractal Models ◽  
Normal Contact Stiffness

Through the analysis and research on three fractal models of normal contact stiffness of joint interfaces, the differences between them can be found. Furthermore, numerical simulation was carried out to obtain the complicated nonlinear relations between normal contact stiffness and the normal load. The results show that the normal contact stiffness increases with the normal load, decreases with G but complicatedly varies with D. According to different fractal dimension, we can chose an appropriate one among the three fractal models of normal contact stiffness of joint interfaces when describing normal contact stiffness of joint interfaces.

scholarly journals Strength of the shaft/hub joint using a finite element model

2019 ◽  
pp. 9-18
Author(s):  
Manuel Salgado-Cruz ◽  
Claudia Cortés-García ◽  
Dariusz Slawomir Szwedowicz-Wasik ◽  
Eladio Martínez-Rayón
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Contact Stiffness ◽  
Load Capacity ◽  
Element Model ◽  
Numerical Results ◽  
Normal Contact ◽  
Interference Fit ◽  
Axial Load Capacity ◽  
Normal Contact Stiffness

This article describes the effect of the roughness size on the axial slip strength between the parts of shaft/hub joints with interference fit. The surface roughness was obtained from a turning process with different finishes (fine, medium and rough). A finite element modeling was developed, which uses a normal contact stiffness equivalent to the size of the surface roughness between the joint pieces to represent the real contact. In order to validate the numerical model, theoretical results of contactpressure and extraction force of the shaft/hub joint with smooth elements were compared with the corresponding numerical results obtained. The numerical results from studies that considered the size of the surface roughness showed that the axial load capacity of the joint decreased with larger roughness.

scholarly journals Stiffness of Carpentry Connections – Numerical Modelling vs. Experimental Test

2015 ◽  
Vol 11 (2) ◽  
pp. 121-135
Author(s):  
Miloš Kekeliak ◽  
Jozef Gocál ◽  
Josef Vičan
Keyword(s):  
Surface Roughness ◽  
Numerical Model ◽  
Numerical Modelling ◽  
Contact Stiffness ◽  
Experimental Tests ◽  
Normal Contact ◽  
Study Results ◽  
Normal Contact Stiffness ◽  
Contact Surfaces ◽  
Mortise And Tenon

Abstract In this paper, numerical modelling of the traditional carpentry connection with mortise and tenon is presented. Numerical modelling is focused on its stiffness and the results are compared to results of experimental tests carried out by (Feio, 2005) [6]. To consider soft behaviour of wood in carpentry connections, which are related to its surface roughness and geometrical accuracy of the contact surfaces, the characteristics of the normal contact stiffness, determined experimentally, are introduced in the numerical model. Parametric study by means of numerical modelling with regard to the sensitivity of connection stiffness to contact stiffness is presented. Based on the study results, in conclusion there are presented relevant differences between the results of numerical modelling and experimental tests (Feio, 2005) [6].

Measurement of Tangential Contact Stiffness in Frictional Contacts: The Effect of Normal Pressure

2011 ◽  
Vol 70 ◽  
pp. 321-326 ◽  
Author(s):  
Mehmet E. Kartal ◽  
Daniel M. Mulvihill ◽  
David Nowell ◽  
Dawid A. Hills
Keyword(s):  
Structural Integrity ◽  
Contact Stiffness ◽  
Testing Machine ◽  
Normal Pressure ◽  
Tangential Direction ◽  
Image Correlation ◽  
Tensile Testing Machine ◽  
Normal Contact ◽  
Tangential Contact ◽  
Frictional Contacts

The tangential contact stiffness of frictional interfaces affects both the vibration response and structural integrity of structures comprising frictional joints. Vibration and structural response of monolithic structures can be predicted very accurately; however, when assemblies of components involve frictional interfaces, additional damping and compliance are present due to these interfaces. These features make it more challenging to predict the vibration characteristics of assemblies with the same degree of accuracy as can be achieved for single components. If these interface properties can be determined, it should then be possible to significantly enhance current models of the vibration of engineering assemblies. Measurements of both force and displacement in the tangential direction are obtained from a series of in-line fretting tests involving flat pads with rounded corners clamped against the flat surface of a specimen which is oscillated by a hydraulic tensile testing machine. In order to measure the local displacement field very close to the contact interface, the digital image correlation (DIC) method is employed. The effect of normal contact pressure on tangential contact stiffness is investigated. Multiple experiments with the same parameters show good repeatability given the number of variables involved.

Measurement of Contact Stiffness for Stiffness Estimation of Machine Tool Supports

2012 ◽  
Vol 523-524 ◽  
pp. 457-462 ◽  
Author(s):  
Daisuke Kono ◽  
Takahiro Inagaki ◽  
Atsushi Matsubara ◽  
Iwao Yamaji
Keyword(s):  
Machine Tool ◽  
Measurement Method ◽  
Contact Stiffness ◽  
Tool Support ◽  
Normal Contact ◽  
Tangential Contact ◽  
Longitudinal Elastic Modulus ◽  
Normal Contact Stiffness ◽  
Elastic Shear ◽  
Unit Normal

The contact stiffness is measured at interfaces of several materials that are often used for the machine tool support. Models of machine tool supports and contact stiffness are described. Then, a measurement method of the contact stiffness is proposed according to the model and demonstrated. The unit normal contact stiffness is 1-2×106 N/mm/mm2 for general steel and cast iron. The unit normal contact stiffness is pSuperscript textositively correlated with the longitudinal elastic modulus. The unit tangential contact stiffness is 1/10-1/5 of the unit normal contact stiffness and not correlated with the elastic shear modulus. The surface roughness of the specimen should be small to reduce the dispersion of the measured unit contact stiffness.

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.

scholarly journals Dynamic Contact Analysis of the Piston and Slipper Pair in Axial Piston Pump

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1217
Author(s):  
Hui Shen ◽  
Zhuxin Zhou ◽  
Dong Guan ◽  
Zhongtao Liu ◽  
Li Jing ◽  
...  
Keyword(s):  
Contact Stiffness ◽  
Normal Displacement ◽  
Radial Clearance ◽  
Contact Radius ◽  
Axial Piston Pump ◽  
Normal Contact ◽  
Tangential Contact ◽  
Normal Contact Stiffness ◽  
Axial Piston ◽  
Maximum Contact

The dynamic analysis model of axial piston pump was established; both the kinematics and dynamics simulation analysis were conducted by virtual prototyping approach. The displacement, velocity, acceleration and stress curves of the piston under different working conditions were investigated. In addition, a ball-in-socket contact model was established, and the effects of hydraulic pressure, piston radius and radial clearance on normal displacement, contact radius, maximum contact pressure, normal contact stiffness and tangential contact stiffness were analyzed comprehensively. The results indicate that the normal displacement, maximum contact pressure, contact radius, normal contact stiffness and tangential contact stiffness can be improved by enlarging the piston radius and decreasing the radial clearance.

Modeling Tangential Contact of Rough Surfaces With Elastic- and Plastic-Deformed Asperities

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Dong Wang ◽  
Chao Xu ◽  
Qiang Wan
Keyword(s):  
Rough Surface ◽  
Normal Load ◽  
Experimental Results ◽  
Partial Slip ◽  
Tangential Load ◽  
Stick Slip ◽  
Normal Contact ◽  
Tangential Contact ◽  
Bilinear Relation ◽  
Proposed Model

A new tangential contact model between a rough surface and a smooth rigid flat is proposed in this paper. The model considers the contribution of both elastically deformed asperities and plastically deformed asperities to the total tangential load of rough surface. The method combining the Mindlin partial slip solution with the Hertz solution is used to model the contact formulation of elastically deformed asperities, and for the plastically deformed asperities, the solution combining the fully plastic theory of normal contact with the bilinear relation between the tangential load and deformation developed by Fujimoto is implemented. The total tangential contact load is obtained by Greenwood and Williamson statistical analysis procedure. The proposed model is first compared to the model considering only elastically deformed asperities, and the effect of mean separation and plasticity index on the relationship between the tangential load and deformation is also investigated. It is shown that the present model can be used to describe the stick–slip behavior of the rough surface, and it is a more realistic-based model for the tangential rough contact. A comparison with published experimental results is also made. The proposed model agrees very well with the experimental results when the normal load is small, and shows an error when the normal load is large.

One Method for Estimating Normal Contact Stiffness with Ra and Adhesion Rate

2013 ◽  
Vol 734-737 ◽  
pp. 2443-2450
Author(s):  
Peng Wang ◽  
Tian Yun Li ◽  
Xiang Zhu ◽  
Guo Xiong Pan
Keyword(s):  
Surface Roughness ◽  
Vibration Isolation ◽  
Contact Stiffness ◽  
Low Noise ◽  
Normal Contact ◽  
Surface Machining ◽  
Fractal Parameters ◽  
Normal Contact Stiffness ◽  
Adhesion Rate ◽  
The Cost

Based on the fractal contact theory, the model about the relation between normal contact stiffness and material properties as well as fractal parameters is established. Then by making use of the relation between fractal parameters and surface roughness, a new method for estimating the normal contact stiffness is put forward. The numerical results indicate that the contact stiffness increases as surface roughness decreases or adhesion rate increases. When the adhesion rate is constant, contact stiffness changes a little whileRa≥6.3μm, but the change is relatively bigger whenRa≤6.3μm. Considering both the cost of surface machining and the influence of contact stiffness on the whole system, the surface roughness is suggested to beRa=6.3μm. The results provide theoretical supports for vibration isolation analysis with gaskets and the process of low-noise construction.

A multi-scale stiffness fractal model of joint interfaces

2021 ◽  
pp. 81-95
Author(s):  
Jingfang Shen ◽  
◽  
Sijie Cheng ◽  
Siyan Wang ◽  
Wenwei Liu ◽  
...  
Keyword(s):  
Contact Mechanics ◽  
Normal Load ◽  
Contact Stiffness ◽  
Roughness Parameter ◽  
Numerical Control ◽  
Joint Interface ◽  
Normal Contact ◽  
Multi Scale ◽  
Stiffness Model ◽  
Fractal Roughness

Stiffness characterization of mechanical interfaces is quite crucial for the analysis of several tribological behaviors. The stiffness of different machine tools varies greatly, particularly for computer numerical control machine. Therefore, this research aims at providing an assessment of influence factors for stiffness of joint interfaces theoretically. Based on fractal roughness parameters independent of scale and contact mechanics theory, the contact area of joint interface is studied, and the multi-scale normal contact stiffness model and multi-scale tangential contact stiffness model are proposed. Meanwhile, the problem of the deformation of any contact asperity is considered as three separate regimes. The laws of area-displacement and force-displacement under elastic-plastic regime are established. The transition which is in the deformation mechanism of asperity from elastic to plastic is consistent with classical contact mechanics. The analysis of numerical calculation results indicates the approximate linear relation among dimensionless normal load and key parameters. Moreover, these key parameters have been divided into two main categories for the multiscale model of joint interfaces, one is fractal parameters such as fractal dimension D and fractal roughness parameter G, and the other is interfacial parameters. In addition, tangential load and friction factor are two important factors to the tangential stiffness.

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