Study on Identification of Contact Stiffness Considering Surface Roughness

2014 ◽  
Vol 1017 ◽  
pp. 441-446 ◽  
Author(s):  
Kyoko Nakamura ◽  
Haruhisa Sakamoto
Keyword(s):  
Surface Roughness ◽  
Contact Area ◽  
Quantitative Measurement ◽  
Experimental Approach ◽  
Contact Stiffness ◽  
Real Contact Area ◽  
Special Device ◽  
Real Contact ◽  
Dominant Configuration ◽  
Simplified Calculation

In previous study, the quantitative measurement method of contact stiffness of the joint considering real contact area is developed by experimental approach. However, the measurement of contact stiffness needs special device and skillful measuring technique. Therefore, in this paper, simplified calculation method with material properties and profile data of surface roughness obtained by profilometer is considered. As a result, real contact area, contact stiffness and contact spring stiffness calculated from specific wavelength of rough surface are near agreement with experimental value. Hence, it is revealed that there is dominant configuration in surface roughness.

A Microcontact Approach for Ultrasonic Wire Bonding in Microelectronics

2000 ◽  
Vol 123 (4) ◽  
pp. 725-731 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Jeng-Haur Horng
Keyword(s):  
Surface Roughness ◽  
Bond Strength ◽  
Contact Area ◽  
Bonding Strength ◽  
Initial Period ◽  
Wire Bonding ◽  
Real Contact Area ◽  
Welding Time ◽  
Real Contact ◽  
Ultrasonic Wire Bonding

Wire bonding is a popular joining technique in microelectronic interconnect. In this study, the effects of applied load, surface roughness, welding power and welding time on bonding strength were investigated using an ultrasonic bonding machine and a pull tester. In order to relate bonding strength to contact phenomena, the asperity model was used to compute real contact area and flash temperature between the wire and the pad. The experimental results show that a decrease in load or ultrasonic power produces a larger weldable range in which the combination of operation parameters allow the wire and pad to be welded. Regardless of roughness and applied loads, the bond strength increases to a maximum with increases in the welding time, and then decreases to fracture between wire and pad. The theoretical results and experimental observations indicate that bond strength curves can be divided into three periods. The contact temperature plays an important role in bonding strength in the initial period, and surface roughness is the dominant factor in the final period. The maximum bonding strength point occurs in the initial period for different loads and surface roughness values. Our results show that bond strength of ultrasonic wire bonding can be explained based on the input energy per real contact area.

Contact stiffness of mating surfaces of parts under dynamic loading

2020 ◽  
pp. 57-60
Author(s):  
M.M. Matlin ◽  
V.A. Kazankin ◽  
E.N. Kazankina ◽  
A.I. Mozgunova
Keyword(s):  
Dynamic Loading ◽  
Contact Area ◽  
Contact Stiffness ◽  
Dynamic Contact ◽  
Real Contact Area ◽  
Contact Loading ◽  
The Real ◽  
Real Contact ◽  
Nominal Pressure ◽  
Plastic Hardness

The dependences of the relative real contact area of the flat contacting surfaces of steel parts on the nominal pressure under dynamic contact loading are studied. It is determined, that the real contact area under dynamic loading is less than under static one. Keywords dynamic plastic hardness, contact approach, real contact area, contact stiffness. [email protected]

Influence of Surface Roughness on Contact Heat Transfer

2010 ◽  
Author(s):  
V. A. Ustinov ◽  
R. Kneer ◽  
F. Al-Sibai ◽  
S. G. Schulz ◽  
E. El-Magd
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Contact Area ◽  
Real Contact Area ◽  
Contact Heat ◽  
Real Contact ◽  
Contact Heat Transfer ◽  
Contact Pressures

Almost all technical devices in use today are assemblies of individual pieces. For all force-based assembly methods, such as bolting or press-fitting, the thermal behavior is influenced by the contact resistance at the joint surface. For metal pieces in contact with each other, the authors have developed a measurement method and analysis tools enabling the determination of the contact heat transfer coefficient. Previously published results [1, 2, 3] have shown the dependence of the contact heat transfer coefficient on surface structure, contact pressure and material properties. The present work provides experimental and analytical data for the contact heat transfer coefficient and also proposes a model for calculating the real contact area of two surfaces which are placed under different contact pressures. Experiments were conducted for two material combinations with three different surface structures, while varying the contact pressures from 7 MPa to 230 MPa. When selecting average surface roughness (Rz) as a characterizing parameter for surface structure, the results did not show a consistent trend. Thus, in this paper Rz was replaced by the real contact area between the two surfaces of interest. This area was determined by applying a refined method based on surface roughness measurements. The experimental data show a better consistency, when plotting the contact heat transfer coefficient relative to real contact area (Fk) rather than the previously used Rz–values.

Micropitting Generation Mechanism for Gears

2008 ◽  
Vol 2 (5) ◽  
pp. 341-347
Author(s):  
Nobuyoshi Yoshida ◽  
◽  
Tokihiko Taki
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Contact Stress ◽  
Contact Area ◽  
Maximum Stress ◽  
Real Contact Area ◽  
Durability Test ◽  
Metallic Contact ◽  
Real Contact ◽  
Surface Durability

To determine the mechanism behind micropitting, we measured micropit shape occurring in surface durability test, based on the real contact area size formed by asperity interaction in surface roughness. Individual micropitting within surface roughness asperity does not exceed asperity size. Micropitting occurs due to contact stress increased by a high friction coefficient due to metallic contact. Stress analysis showed that maximum stress causes micropitting.

scholarly journals Investigation of running-in process based on surface roughness parameters, real contact area ratio and tribological properties

2021 ◽  
Vol 49 (4) ◽  
pp. 988-996
Author(s):  
Jeng-Haur Horng ◽  
Dipto Biswas ◽  
A Adhitya ◽  
Qumrul Ahsan
Keyword(s):  
Surface Roughness ◽  
Contact Area ◽  
Roughness Parameter ◽  
Area Ratio ◽  
Real Contact Area ◽  
Stable Relationship ◽  
Real Contact ◽  
Shape Adjustment ◽  
Rigid Smooth ◽  
Contact Area Ratio

The running-in process is the initial process for the new moving parts wearing against each other to establish the shape adjustment that will regulate them into a stable relationship for the rest of their working life. The objective of this research is to investigate and evaluate the running-in process by using disk-on-block line contact device. Due to its empirical nature and well-ploughed analysis, an asperity micro-contact model is considered. The experiment is performed by varying the surface roughness of the block with rigid smooth sphere surface under specific condition. The effects of surface roughness, load, speed, and lubrication on the running-in behaviour is studied. The running-in process encourage plastic deformation of asperities and created microstructural changes on contact surfaces. The theoretical and experiment result shows that the plasticity index ps, surface roughness parameter b, real contact area ratio * A0 and specific film thickness l is influenced by the running-in process.

FEA-Based Numerical Simulation and Theoretical Modeling for Predicting Thermal Contact Conductance

2018 ◽  
pp. 118-139
Author(s):  
Sachin Rana
Keyword(s):  
Surface Roughness ◽  
Contact Area ◽  
Loading Condition ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Real Contact Area ◽  
Fem Model ◽  
Contact Conductance ◽  
Real Contact ◽  
Fine Mesh

The chapter states the problem of thermal contact conductance between surfaces. Rough surface generation and thermal contact conductance has been simulated using Finite Element Method (FEM) based Ansys. The resulting geometry is meshed by different meshing method to convert the solid model into FEM model. The main aim of meshing is to create fine and coarse mesh at the contact to reduce the computational time. To create a fine mesh at contact free meshing with refinement and mapped mesh has been used. The analysis has been performed on the FEM model with varying loading condition of different surface roughness and different materials to get the real contact area and thus thermal contact conductance. The variation of thermal contact conductance and real contact area with pressure of different surface roughness and with surface roughness of different loading condition of the specimen made of aluminum and mild steel has been plotted and compared.

Surface fractal topography-based contact stiffness determination of spindle–toolholder joint

2015 ◽  
Vol 230 (4) ◽  
pp. 602-610 ◽  
Author(s):  
Yongsheng Zhao ◽  
Xiaolei Song ◽  
Ligang Cai ◽  
Zhifeng Liu ◽  
Qiang Cheng
Keyword(s):  
Contact Force ◽  
Contact Area ◽  
High Speed ◽  
Contact Stiffness ◽  
Fractal Theory ◽  
Contact Model ◽  
Real Contact Area ◽  
Real Contact ◽  
Fractal Parameters ◽  
Relationship Of

Accurate modeling of contact stiffness is crucial in predicting the dynamic behavior and chatter vibration of spindle–toolholder system for high-speed machining centers. This paper presents a fractal theory-based contact model of spindle–toolholder joint to obtain the contact stiffness and its real contact area. Topography of the contact surfaces of spindle–toolholder joint is fractal featured and determined by fractal parameters. Asperities in micro-scale are considered as elastic or plastic deformation. Then, the contact stiffness, the real contact area, the elastic contact force, and the plastic contact force of the whole contact surface are calculated by integrating the micro asperities. The relationship of the contact stiffness and the drawbar force follows a power law, in which the power index is determined by the fractal parameters. Experiments are conducted to verify the efficiency of the proposed model. The results from the fractal contact model of spindle–toolholder joint have good agreement with those of experiments.

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

2012 ◽  
Vol 40 (2) ◽  
pp. 124-150
Author(s):  
Klaus Wiese ◽  
Thiemo M. Kessel ◽  
Reinhard Mundl ◽  
Burkhard Wies
Keyword(s):  
Coefficient Of Friction ◽  
Liquid Layer ◽  
Contact Area ◽  
Leading Edge ◽  
Viscous Friction ◽  
Analytical Approximation ◽  
Real Contact Area ◽  
Length Scales ◽  
Real Contact ◽  
Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

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