Theoretical Model for the Contact Stiffness and Damping of Mechanical Joint Surface

2017 ◽  
Vol 53 (9) ◽  
pp. 073
Author(s):  
Weiping FU
Keyword(s):  
Theoretical Model ◽  
Contact Stiffness ◽  
Joint Surface ◽  
Mechanical Joint ◽  
Stiffness And Damping

scholarly journals Research on the micro and dynamic characteristics of combination surface based on fractal theory

2020 ◽  
Vol 11 (1) ◽  
pp. 1-27
Author(s):  
Chunxia Zhu ◽  
Zhibiao Yan
Keyword(s):  
Theoretical Analysis ◽  
Dynamic Characteristics ◽  
Optimization Design ◽  
Contact Stiffness ◽  
Fractal Theory ◽  
Joint Surface ◽  
Tangential Contact ◽  
Surface Parameters ◽  
Mechanical Joint ◽  
Texture Parameters

Abstract. The dynamic characteristics of the mechanical joint surface are important aspects of the dynamic theoretical analysis and optimization design of the machine tool. In this paper, the typical mechanical joint surface is taken as the research object. Through the combination of theoretical analysis and experimental analysis, the dynamic characteristics of typical joint surface parameters with different surface textures and the influence of texture parameters on the dynamic characteristics of the joint surface are studied. Based on the Hertz elastic contact theory and the contact fractal theory, the normal and tangential contact fractal models of the joint surface are derived, and then a mathematical model of the joint surface normal and tangential contact stiffness considering the domain expansion factor is established. The influence of surface texture parameters on the dynamic characteristics of the surface is further studied according to the model. In addition, the design of the experimental device and experimental scheme design are completed by the contact resonance method and the ERA algorithm, and the joint surface parameter identification experiment with texture is conducted. The normal and tangential frequency response functions of the joint surface, the dynamic characteristic parameters of the joint surface and the influence law of the joint surface parameters on the contact characteristics are obtained through the dynamic test analysis technology.

A detachable design method of large-sized structure for heavy duty machine tool based on joint surface dynamics characteristic analysis

2019 ◽  
Vol 233 (13) ◽  
pp. 4476-4489 ◽  
Author(s):  
Qiang Cheng ◽  
Baobao Qi ◽  
Zhifeng Liu ◽  
Guojun Zhang ◽  
Caixia Zhang ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Machine Tools ◽  
Design Method ◽  
Contact Stiffness ◽  
Joint Surface ◽  
Optimized Design ◽  
Heavy Duty ◽  
Characteristic Analysis ◽  
Structural Part ◽  
Stiffness And Damping

Heavy duty and ultra-heavy duty machine tools are used to manufacture large parts or super large parts in aerospace, ship, transportation, and energy industries. The weight of a structural part of ultra-heavy duty machine tools will reach more than 100 tons, because of which both manufacturing and transportation become very difficult. In this paper, a detachable design method for large-sized structures of heavy duty machine tools is presented. The proposed method aims to make large-sized structure into several detachable sections that can be bolted together in order to be casted and transported and remanufactured more easily. To analyze the influence of the joint surface, a three-dimensional fractal contact model based on the influence of domain expansion factor is used to identify stiffness and damping of the joint surface. On the basis of the analysis of the dependence of contact stiffness and damping of joint surface on dynamic characteristics of structural part, a detachable optimization model of a super span beam is established, and the particle swarm optimization algorithm is adopted to carry out the optimization. After that, the dynamic characteristics of the optimized design is analyzed and verified by finite element analysis. Based on the simulated verification, a detachable beam of heavy duty gantry machine was designed by the proposed method and verified by the field test. The illustration example shows that the large span beam can be detached into three sections that can be bolted together by high strength bolts, and it also has satisfied performance.

scholarly journals A New Method for Modeling Mechanical Joint Surface Contact Stiffness

2020 ◽  
Vol 56 (9) ◽  
pp. 162
Author(s):  
LI Ling ◽  
WANG Jingjing ◽  
PEI Xiyong ◽  
CHU Wei ◽  
CAI Anjiang
Keyword(s):  
Contact Stiffness ◽  
New Method ◽  
Joint Surface ◽  
Mechanical Joint ◽  
Surface Contact

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.

scholarly journals Contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions

Friction ◽  
2021 ◽  
Author(s):  
Zongzheng Wang ◽  
Wei Pu ◽  
Xin Pei ◽  
Wei Cao
Keyword(s):  
Contact Stiffness ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Dry Contact ◽  
Spiral Bevel ◽  
Stiffness And Damping ◽  
Lubrication Conditions ◽  
Film Lubrication

AbstractExisting studies primarily focus on stiffness and damping under full-film lubrication or dry contact conditions. However, most lubricated transmission components operate in the mixed lubrication region, indicating that both the asperity contact and film lubrication exist on the rubbing surfaces. Herein, a novel method is proposed to evaluate the time-varying contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions. This method is sufficiently robust for addressing any mixed lubrication state regardless of the severity of the asperity contact. Based on this method, the transient mixed contact stiffness and damping of spiral bevel gears are investigated systematically. The results show a significant difference between the transient mixed contact stiffness and damping and the results from Hertz (dry) contact. In addition, the roughness significantly changes the contact stiffness and damping, indicating the importance of film lubrication and asperity contact. The transient mixed contact stiffness and damping change significantly along the meshing path from an engaging-in to an engaging-out point, and both of them are affected by the applied torque and rotational speed. In addition, the middle contact path is recommended because of its comprehensive high stiffness and damping, which maintained the stability of spiral bevel gear transmission.

Finite Element Analysis for Machine Joint

2010 ◽  
Vol 26-28 ◽  
pp. 198-203
Author(s):  
Tie Neng Guo ◽  
Ling Li ◽  
Li Gang Cai ◽  
Zhi Feng Liu
Keyword(s):  
Dynamic Characteristic ◽  
Maximum Error ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Element Analysis ◽  
Mechanical Joint ◽  
Result Show ◽  
Joint Element ◽  
Stiffness And Damping ◽  
Five Axis

The stiffness and damping of mechanical joint are modeled by the zero thickness joint interfaces theory. The method is applied to analyze the dynamic characteristic of the gantry frame in a five axis turning-milling compound CNC machine tool. The model test is carried out in the gantry frame, and the maximum error of the first sixth mode is 5.63%. The experimental and analysis result show the zeros thickness joint element can provide an effective method to model the machine joint and predict the dynamic characteristic of the assembled structure.

Lorentz Contact Resonance Imaging for Atomic Force Microscopes: Probing Mechanical and Thermal Properties on the Nanoscale

2013 ◽  
Vol 21 (6) ◽  
pp. 18-24 ◽  
Author(s):  
Eoghan Dillon ◽  
Kevin Kjoller ◽  
Craig Prater
Keyword(s):  
Viscoelastic Properties ◽  
Contact Stiffness ◽  
Mechanical And Thermal Properties ◽  
Resonance Modes ◽  
Atomic Force ◽  
Resonance Frequencies ◽  
Other Information ◽  
Afm Cantilever ◽  
Stiffness And Damping ◽  
Contact Resonance

Atomic force microscopy (AFM) has been widely used in both industry and academia for imaging the surface topography of a material with nanoscale resolution. However, often little other information is obtained. Contact resonance AFM (CR-AFM) is a technique that can provide information about the viscoelastic properties of a material in contact with an AFM probe by measuring the contact stiffness between the probe and sample. In CR-AFM, an AFM cantilever is oscillated, and the amplitude and frequency of the resonance modes of the cantilever are monitored. When a probe or sample is oscillated, the tip sample interaction can be approximated as an ideal spring-dashpot system using the Voigt-Kelvin model shown in Figure 1. Contact resonance frequencies of the AFM cantilever will shift depending on the contact stiffness, k, between the tip and sample. The damping effect on the system comes from dissipative tip sample forces such as viscosity and adhesion. Damping, η, is observed in a CR-AFM system by monitoring the amplitude and Q factor of the resonant modes of the cantilever. This contact stiffness and damping information can then be used to obtain information about the viscoelastic properties of the material when fit to an applicable model.

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.

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