On the Prediction of Transient Wear

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Vahid Mortazavi ◽  
M. M. Khonsari
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Wear Rate ◽  
Linear Relationship ◽  
Coefficient Of Friction ◽  
Friction Pair ◽  
Wear Loss ◽  
Initial Surface ◽  
Pi Theorem ◽  
Tribological Parameters

During the running-in process, a friction pair experiences drastic evolution in many of its tribological parameters, such as surface roughness, wear rate, and coefficient of friction until steady-state is attained. In this paper, we present a model for predicting the behavior of the running-in process. Specifically, we determine a general relationship between the wear loss and surface roughness during the running-in stage and test the validity of its prediction of wear rate by comparing to available experimental results. We show, by using a dimensional analysis and applying the Buckingham Pi theorem, that there exists a linear relationship between the transient dimensionless wear, the dimensionless initial surface roughness, and dimensionless running-in time.

scholarly journals Experimental Investigation on the Wear and Damage Characteristics of Machined Wheel/Rail Materials under Dry Rolling-Sliding Condition

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 472
Author(s):  
Peijie Liu ◽  
Yanming Quan ◽  
Junjie Wan ◽  
Lang Yu
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Surface Defects ◽  
Wear Behavior ◽  
Friction Pair ◽  
Surface Hardness ◽  
Wear Testing ◽  
Wear Loss ◽  
Machining Parameters ◽  
Deformation Layer

To guarantee the smooth operation of trains, rail grinding and wheel turning are necessary practices to remove surface defects. Surface integrity of machined wheel/rail materials is significant to affect their tribological performance. In this paper, firstly, the wheel specimens were turned by a CNC lathe and the rail specimens were ground by a cylindrical grinding machine with various machining parameters. Then, the wear and damage behavior of the machined wheel/rail discs was systematically investigated via a twin-disc wear testing apparatus under dry rolling-sliding condition. The experimental results show that the surface hardness of rail discs after machining is slightly higher than that of wheel discs, while the surface roughness and plastic deformation layer of wheel discs are much larger than those of rail discs. The surface hardness increase degree of rail discs and their thickness of plastic deformation layer are greater than those of wheel discs after the rolling-sliding test. The wear loss of wheel discs is much larger than that of rail discs. Surface roughness, hardness and plastic deformation layer of wheel/rail discs after machining exert a comprehensive effect on the wear behavior, and friction pair with appropriate original surface hardness and roughness generates the smallest amount of wear loss.

The Influence of Initial Commutator Surface Roughness on Wear of the Starter Motor Commutation System

2014 ◽  
Vol 966-967 ◽  
pp. 96-102
Author(s):  
Tanja Spremberg ◽  
Ingo Engler ◽  
Berend Denkena
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Mechanical Load ◽  
Life Time ◽  
The Other ◽  
Initial Surface ◽  
Test Rig ◽  
Starter Motor ◽  
Tribological System ◽  
Load Tests

One way to improve the run-in period of the commutation system of an electrical motor is the modification of the commutator ́s roughness. The reduction of the run-in period affects the wear during the motor life time. Therefore, within this paper the influence of the initial commutator roughness on the run-in period and the electromechanical wear is investigated. The research is done with a special starter components test rig. During the tests the wear is analyzed while the applied electromechanical and mechanical load is varied in order to enforce different wear behaviors. It is expected that with an optimal initial surface roughness the amount of wear is reduced until the steady state has been reached. However, the results revealed that there is no significant influence of the initial surface roughness on the examined electromechanical tribological system. It was found, that the mechanical wear of the commutator and the brushes is similar to the electromechanical wear during the run-in period. The run-in period of the mechanical load tests is shorter compared to the other experiments.

scholarly journals Experimental Investigation on the Wear and Damage Behaviors of Machined Wheel-Rail Materials under Dry Sliding Conditions

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 540
Author(s):  
Peijie Liu ◽  
Yanming Quan ◽  
Junjie Wan ◽  
Lang Yu
Keyword(s):  
Surface Roughness ◽  
Surface Defects ◽  
Numerical Control ◽  
Wear Loss ◽  
Wear Property ◽  
Initial Surface ◽  
Surface Microhardness ◽  
Machined Surface ◽  
Dry Conditions ◽  
Grinding Machine

Rail grinding and wheel turning can effectively remove surface defects and unevenness, which is a crucial process for the safe and smooth operation of trains. Machined surface integrity of wheel/rail materials significantly influences their tribological property. In this study, firstly, the rail blocks were ground via a cylindrical grinding machine, and the wheel rings were turned by a computer numerical control (CNC) lathe with varied parameters. Then, the sliding wear and damage characteristics of the machined wheel/rail samples under dry conditions were studied by virtue of a block-on-ring tribometer. The results show that the surface microhardness of the ground rail blocks is larger than that of wheel rings, while the surface roughness and the thickness of the subsurface plastic deformation layer (SPDL) of rail blocks are much smaller than those of wheel rings. After sliding, the surface microhardness of wheel/rail samples increases remarkably. The thickness of the SPDL, the wear loss, and the increase degree of surface microhardness of rail blocks are larger than those of wheel rings. Surface microhardness, roughness and the SPDL of the machined wheel/rail samples impose a combined influence on the anti-wear property, and the tribological pair with proper initial surface roughness and microhardness engenders the smallest amount of total wear loss.

scholarly journals Effect of Steel Surface Roughness and Expanded Graphite Condition on Sliding Layer Formation

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2960
Author(s):  
Aleksandra Rewolińska ◽  
Karolina Perz ◽  
Grzegorz Kinal
Keyword(s):  
Surface Roughness ◽  
Steel Surface ◽  
Friction Pair ◽  
Expanded Graphite ◽  
Initial Surface ◽  
Layer Formation ◽  
Material Transfer ◽  
Surface Geometry ◽  
First Case ◽  
Ring Pin

The aim of the research was to evaluate the influence of the initial roughness of a steel pin cooperating with a graphite ring—dry and wet—on the mechanism of sliding layer formation. A ring–pin friction pair was used for the study, where the rings were made of expanded graphite, while the pins were made of acid-resistant steel. In the first case, the steel pin interacted with a dry graphite ring, and in the second case, the graphite rings were moist. To determine the effect of initial surface roughness, the pins were divided into three roughness groups. To determine changes in surface geometry due to material transfer, the Ra and Rz parameters were measured. This project investigated how the initial roughness value of the steel surface pin cooperating with expanded graphite influences the formation of the sliding layer. Increasing the initial roughness of the steel surface interacting with the graphite contributes to faster layer formation and reduced roughness. The state of the expanded graphite—dry and wet—influences the formation of the sliding layer of graphite—a wet graphite component causes a faster smoothing of the steel surface. The running time of the wear apparatus has an effect on the resulting layer. The highest roughness group is the most favorable from the viewpoint of sliding layer formation.

Wear Testing of Principal Friction Pairs in Axial Piston Pump Based on Taguchi Design Method

2015 ◽  
Vol 779 ◽  
pp. 26-34 ◽  
Author(s):  
Cun Ran Zhao ◽  
Ji Hai Jiang ◽  
Chong Ke
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Design Method ◽  
Friction Pair ◽  
Piston Pump ◽  
Wear Testing ◽  
Wear Loss ◽  
Axial Piston Pump ◽  
Axial Piston ◽  
Selection Of

While axial piston pump is the core component of hydraulic system, its service life and reliability depend much on the selection of materials, friction pairs and process parameters. To identify these factors, wear condition of friction pair is conducted by using MWF-10 wear rig. Based on ANOVA of Taguchi Method,the influences of surface roughness and hardness on wear loss and friction coefficient are compared. In addition, the results show that the optimal friction pair and surface roughness of hard specimens have influence mostly on the wear loss and the friction coefficient.

Wear Characteristics of Al7075/Al2O3/SiC Hybrid Metal Matrix Nano Composites

2021 ◽  
Vol 1034 ◽  
pp. 43-49
Author(s):  
N. Sreedhar
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Metal Matrix ◽  
Weight Fraction ◽  
Wear Loss ◽  
Matrix Metal ◽  
Wear Characteristics ◽  
The Matrix ◽  
Sliding Distance

In the present investigation Aluminum matrix composites (AMMCs), Al7075 Alloy as matrix metal and Al2O3/SiC particles (2-8%) with an average particulate size of 20, 50 nm as strengthened material have been processed by the stir casting method. For the counter surface wear testing, a computerized pin on a wear tester was used as EN31 (58-60 HRC) steel disc and composite pin. The wear rate for the matrix metal and composites in terms of weight loss per unit sliding distance, friction coefficient, and volume loss were achieved. The composite results show better resistance to wear than matrix metal. SEM was used to investigate the microstructural characterization of worn surfaces. Sample weight loss was calculated and the change in cumulative wear loss at a sliding distance was uniform both for metal matrix as well as for composites. The wear speed for composites was also noted to be small compared to the metal matrix. In addition, experiments have shown that, with the increasing weight fraction of Al2O3/SiC and the coefficient of friction increases with increasing sliding velocity and weight fraction of Al2O3/SiC, the wear rate reduces. The wear characteristics (wear rate, coefficient of friction and wear loss) were better than those of other composites and the matrix metal with 6wt% Al2O3/SiC composites.

A Comparative Study of Microstructure, Coefficient of Friction and Wear Rate of Alloy Ni-Cr-B-Si-C-W

2021 ◽  
Vol 406 ◽  
pp. 229-239
Author(s):  
Mohamed Nabil Bachirbey ◽  
Mohammed Seyf Eddine Bougoffa ◽  
Chahrazed Benouali ◽  
Tahar Sayah
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Sliding Friction ◽  
Wear Behavior ◽  
Normal Load ◽  
New Approach ◽  
The Coefficient Of Friction ◽  
Loss Of Mass ◽  
Tribological Parameters

The present work aims at the study of the dry disc pion contact and the complex phenomenon of the wear as well as the sliding friction of our sample elaborated by a hot isotactic compression and the pion. This study consists in determining the coefficient of friction and the influence of the tribological parameters on this phenomenon as well as determining the loss of mass and the wear rate of study sample. In order to enhance the assurance of the validity of the results of tribological study of Ni-Cr-B-Si-C-W alloy in laboratories and compare that to the tribological conditions in reality and industries. This work presents the results of the new approach to compares the wear behavior of the sample between a theoretical study (tribometer)and another in service (a test bench) that reproduces approximately the same conditions as the tribometer (normal load, sliding speed and distance traveled) by measuring the loss of mass and wear rate.

scholarly journals Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Applied Load ◽  
Practical Significance ◽  
Tribological Characteristics ◽  
M 10 ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

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