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.

Partial Film Lubrication Characteristics of Inlet Zone in Cold Strip Rolling

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Kuo Fu ◽  
Yong Zang ◽  
Zhiying Gao
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Contact Area ◽  
Friction Stress ◽  
Area Ratio ◽  
Work Zone ◽  
Zone Length ◽  
Inlet Zone ◽  
Pressure Stress ◽  
Contact Area Ratio

According to the average flow Reynolds equation and rolling theory, a partial film lubrication model of inlet zone has been developed. The model mainly simulates and reflects the influence of surface topography on the inlet film thickness and inlet zone length. Based on the surface topography analysis, a method to judge the friction condition was proposed. All the calculation was conducted by a numerical method. The result shows that the transverse stripe increases the inlet film thickness and the inlet zone length, while the longitudinal stripe decreases them. The surface roughness will enhance this effect. The surface roughness and the stripe direction also have a significant influence on the contact area ratio and the distribution of stress and film thickness in work zone. Transverse stripe increases the lubricant film thickness and separates the roll and the sheet with a larger distance in work zone. It also decreases the contact area ratio, the pressure stress and friction stress of the work zone. Whereas longitudinal stripe decreases the film thickness and increases the contact area ratio, pressure stress and friction stress. The surface roughness increases the contact area ratio, pressure stress and friction stress.

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.

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.

FEM Analysis of Hydrostatic Pressure Generated Within Lubricant Entrapped Into Pocket on Workpiece Surface in Upsetting Process

1999 ◽  
Vol 122 (4) ◽  
pp. 822-827 ◽  
Author(s):  
Akira Azushima
Keyword(s):  
Hydrostatic Pressure ◽  
Contact Area ◽  
Plastic Material ◽  
Quantitative Relationship ◽  
Normal Pressure ◽  
Area Ratio ◽  
Real Contact Area ◽  
Bulk Deformation ◽  
Rigid Plastic ◽  
Contact Area Ratio

In order to investigate into the quantitative relationship between the hydrostatic pressure generated within the surface pocket of the workpiece and the normal pressure acting on the real contact area at the interface of metal forming such as drawing, rolling, forging and so on, the hydrostatic pressure is calculated accompanied with reduction in height in upsetting of cylinders having a central conical impression or a central conical dent filled with lubricant on the top surface, using the rigid-plastic finite element method. The formulated is based on the plasticity theory. The material is assumed to be rigid perfectly plastic material. It is assumed that the hydrostatic pressure is generated accompanied with a volume change in the surface pocket for compressible lubricants. The results obtained from the calculation are as follows: (1) The hydrostatic pressure generated within the lubricant in a central conical impression in cylindrical upsetting approaches the yield stress at a reduction in height of about 4 percent; (2) The hydrostatic pressure generated within the lubricant in a central conical dent in cylindrical upsetting having an annular asperity increases linearly and abruptly with increasing height reduction when the contact area ratio is small and the bulk deformation is elastic, and it increases gradually and the maximum value approaches the normal pressure acting on the contact area when the contact area ratio becomes large and the bulk deformation is plastic. [S0742-4787(00)00503-8]

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.

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.

The Surface Parameters Analysis of Magnesium Alloys Sheet during Warm Isothermal Forming

2015 ◽  
Vol 642 ◽  
pp. 217-221
Author(s):  
Tung Sheng Yang ◽  
Z.X. Yang ◽  
Sheng Yi Chang
Keyword(s):  
Finite Element Analysis ◽  
Surface Roughness ◽  
Finite Element ◽  
Magnesium Alloys ◽  
Contact Area ◽  
Normal Pressure ◽  
Area Ratio ◽  
Element Analysis ◽  
Surface Parameters ◽  
Contact Area Ratio

This study uses the finite element method (FEM) to predict the workpiece surface parameters, including contact area ratio and surface roughness, of asperity flattening in indentation and sliding contact for magnesium alloys sheet during warm isothermal forming. Contact area ratio and surface roughness are investigated for different process and material parameters, such as sliding distance, temperature, normal pressure and bulk strain rate by finite element analysis. The predicted results of the surface parameters from the finite element analysis are in good agreement with the results obtained from experiments.

Effect of Surface Roughness and Lubricant on Scuffing Initiation

2012 ◽  
Author(s):  
Jiman Han ◽  
Qian Zou
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Contact Area ◽  
Thickness Distribution ◽  
Research Work ◽  
Elastohydrodynamic Lubrication ◽  
Area Ratio ◽  
Contact Area Ratio ◽  
Effect Of Surface

Scuffing failure generally occurs at oil film breakdown and large amount of metal-to-metal interaction between the contacting surfaces, where the role of surface roughness and lubricant becomes prominent. In order to evaluate the effect of surface roughness and lubricant on scuffing, scuffing simulation was carried out using contact mechanics and plasto-elastohydrodynamic lubrication model (MixedPEHL) by taking into account the plastic deformation in the contact area. The evolution of pressure, film thickness, contact area ratio, and subsurface effective plastic strain (EPS) was performed with three types of surface roughness and two different lubricants. Comparisons of pressure distribution, film thickness distribution, film thickness to surface roughness ratio (λ ratio), and contact area ratio were described to investigate the effect of surface roughness and lubricants on scuffing behavior. A better understanding on the effect of surface roughness and lubricant on scuffing processes was obtained through the research work.

Influence of Vibration Time and Frequency on Surface Finishing Using Vibration-Assisted Micro-Forging

2013 ◽  
Vol 773-774 ◽  
pp. 687-693
Author(s):  
Yang Bai ◽  
Ming Yang
Keyword(s):  
Contact Area ◽  
Surface Deformation ◽  
Real Contact Area ◽  
Surface Finishing ◽  
Metal Foil ◽  
Foil Surface ◽  
Real Contact ◽  
Vibration Time ◽  
Nominal Contact Area ◽  
Contact Area Ratio

Vibration-assisted micro-forging was proposed for metal foil surface finishing. The mechanism was investigated by analysis of strain, surface roughness, microhardness, real / nominal contact area ratio and forming work at different vibration time and frequencies. Results show that vibration time and frequency influence the surface deformation by means of real contact area and forming work accordingly.

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