scholarly journals Analysis of Rail Wear Rate according to Wheel/Rail Contact Pressure on Curved Track

2017 ◽  
Vol 20 (4) ◽  
pp. 512-520 ◽  
Author(s):  
Deok-Yong Sung
Keyword(s):  
Wear Rate ◽  
Contact Pressure ◽  
Rail Wear ◽  
Curved Track

Development and Validation of a Finite Element Model of Wear in Uhmwpe Liner Using Experimental Data From Hip Simulator Studies

2021 ◽  
Author(s):  
Nihal Kottan ◽  
Gowtham N H ◽  
Bikramjit Basu
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Wear Rate ◽  
Contact Pressure ◽  
Correction Factor ◽  
Linear Wear ◽  
Maximum Relative Error ◽  
Fe Model ◽  
3D Point Clouds ◽  
Dynamic Wear

Abstract The wear of acetabular liner is one of the key factors determining the longevity and osseointegration of Total Hip Replacement (THR) implants. The long-term experimental measurements of wear in THR components are time and cost-intensive. A finite element (FE) model of a 32 mm Ceramic on Polymer system consisting of ZTA (Zirconia-toughened Alumina) femoral head and UHMWPE (Ultrahigh molecular weight polyethylene) liner was developed to predict the dynamic wear response of the liner. Archard-Lancaster equation, consisting of surface contact pressure, wear rate, and sliding distance, was employed to predict the wear in the liner. The contact pressure and wear at the articulating surface were found to decrease over time. A new computational method involving 3D point clouds from the FE analyzed results were used to construct wear maps. The model was able to predict the linear wear with relative errors ranging from 9% to 36% over 2 million cycles when compared to the published results. The increasing error percentage occurring primarily from the use of a constant wear rate was reduced to a maximum of 17% by introducing a correction factor. Volumetric wear rate was predicted with a maximum relative error of 7% with the implementation of the correction factor. When the model was implemented to study liners of diameters ranging from 28 mm to 36 mm, the linear wear was seen to decrease with an increase in femoral head diameter, which is in agreement with the clinical data.

scholarly journals Study on Rail Profile Optimization Based on the Nonlinear Relationship between Profile and Wear Rate

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Jianxi Wang ◽  
Zhiqiang Ren ◽  
Jinjie Chen ◽  
Long Chen
Keyword(s):  
Support Vector Machine ◽  
Wear Rate ◽  
Optimization Model ◽  
Dynamic Performance ◽  
Support Vector ◽  
Nonlinear Relationship ◽  
Support Vector Machine Regression ◽  
Vertical Coordinate ◽  
Rail Wear ◽  
Profile Optimization

This paper proposes a rail profile optimization method that takes account of wear rate within design cycle so as to minimize rail wear at the curve in heavy haul railway and extend the service life of rail. Taking rail wear rate as the object function, the vertical coordinate of rail profile at range optimization as independent variable, and the geometric characteristics and grinding depth of rail profile as constraint conditions, the support vector machine regression theory was used to fit the nonlinear relationship between rail profile and its wear rate. Then, the profile optimization model was built. Based on the optimization principle of genetic algorithm, the profile optimization model was solved to achieve the optimal rail profile. A multibody dynamics model was used to check the dynamic performance of carriage running on optimal rail profile. The result showed that the average relative error of support vector machine regression model remained less than 10% after a number of training processes. The dynamic performance of carriage running on optimized rail profile met the requirements on safety index and stability. The wear rate of optimized profile was lower than that of standard profile by 5.8%; the allowable carrying gross weight increased by 12.7%.

Experimental Validation of Fretting Fatigue Strength and Fretting Wear Rate at Contact Surface of Turbine-Blade-Shroud Cover

2012 ◽  
Author(s):  
Kunio Asai ◽  
Takeshi Kudo ◽  
Hideo Yoda
Keyword(s):  
Fatigue Strength ◽  
Wear Rate ◽  
Contact Pressure ◽  
Contact Force ◽  
Contact Surface ◽  
Fretting Fatigue ◽  
Fretting Wear ◽  
Dissipated Energy ◽  
Normal Contact ◽  
Vibratory Load

In continuously coupled blade structures, fretting fatigue and wear have to be considered as supposed failure modes at the contact surface of the shroud cover, which is subject to steady contact pressure from centrifugal force and the vibratory load of the blade. We did unique fretting tests that modeled the structure of the shroud cover, where the vibratory load is only carried by the contact friction force, i.e., a type of friction. What was investigated in this study are fretting fatigue strength, wear rate, and friction characteristics, such as friction coefficient and slip-range of 12%-Cr steel blade material. The friction-type tests showed that fretting fatigue strength decreases with the contact pressure and a critical normal contact force exists under which fretting fatigue failure does not occur at any vibratory load. This differs from knowledge obtained through pad-type load carry tests that fretting fatigue strength decreases with the increase of contact pressure and that it almost saturates under a certain contact pressure. Our detailed observation in the friction-type tests clarified that this mechanism was the low contact pressure narrowing the contact area and a resulting high stress concentration at a local area. The fretting wear rate was explained by the dissipated energy rate per cycle obtained from the measured hysteresis loop between the relative slip range and the tangential contact force. This fretting wear rate per cycle is almost the same as the general adhesion wear rate when energy dissipation per cycle is high, and the former is smaller than the latter as the dissipated energy decreases. Finally, to prevent fretting fatigue and wear, we propose an evaluation design chart of the contact surface of the shroud cover based on our friction-type fretting tests.

Numerical analysis of the effect of track parameters on the wear of turnout rails in high-speed railways

2016 ◽  
Vol 232 (3) ◽  
pp. 709-721 ◽  
Author(s):  
Jingmang Xu ◽  
Ping Wang ◽  
Jian Wang ◽  
Boyang An ◽  
Rong Chen
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
High Speed ◽  
Numerical Procedure ◽  
Dynamic Interaction ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Wear Model ◽  
Rail Wear ◽  
Railway Turnout

In this study, a numerical procedure is developed to predict the wear of turnout rails, and the effect of track parameters is investigated. The procedure includes simulation of the dynamic interaction between the train and the turnout, the rolling contact analysis, and the wear model. The dynamic interaction is simulated with the validated commercial software Simpack that uses a space-dependent model of a railway turnout. To reproduce the actual operating conditions of a railway turnout, stochastic variations in the input parameters are considered in the simulation of the dynamic interaction. The rolling contact is analyzed with the semi-Hertzian method and improved FASTSIM algorithm, which enable the contact model to deal with situations of multipoint contact and nonelliptic contact. Based on the Archard’s wear law, the wear model requires the calculation of normal/tangential stresses and a relative slide on the contact patches. The numerical procedure is performed for the selected sections of the vehicle, which runs through the railway turnout in the diverging route. By using the numerical procedure, the effect of track parameters (track gage, rail inclination, and friction coefficient) on the wear of turnout rails is analyzed. The results show that the wear of the front wheelset is more serious than the wear of the rear wheelset for a single vehicle. The degree of wear of switch rails is more severe than that of the stock rails and the difference is more obvious for the front wheelset of the switch rails. The wear of switch rails is mainly concentrated on the rail gage corner, while the wear of stock rails is mainly concentrated on the rail crown. For the analysed CN60-1100-1:18 turnout and the high-speed vehicle CRH2 in China, the rail wear rate could be slowed down by increasing the track gage and decreasing the rail inclination. Alternatively, the rail wear rate could be slowed by decreasing the friction coefficient; however, the variation of wear depth is quite small for friction coefficients that are larger than 0.3.

A Novel Model of Steady-State Sliding Wear with Electrical Current

2011 ◽  
Vol 306-307 ◽  
pp. 782-786
Author(s):  
Zhen Hai Yang ◽  
Yong Zhen Zhang ◽  
Fu Xiao Chen ◽  
Bao Shangguan
Keyword(s):  
Steady State ◽  
Wear Rate ◽  
Contact Pressure ◽  
Sliding Wear ◽  
Electrical Current ◽  
Sliding Velocity ◽  
Novel Model

A novel model of steady-state sliding wear with electrical current was created, which gives an accurate relational expression of three factors (electrical current, sliding velocity and contact pressure) and wear rate of the pin material. The experiments were carried out on the couple of QCr0.5 against copper-based powder metallurgical materials. The results show that the model is accurate and it is able to clearly show the influence of electrical current, sliding velocity and contact pressure on wear rate of pin.

The Effect of the Slip Ratio in Sagittal Plane on the Wear of UHMWPE Bearings in TKR

2012 ◽  
Vol 271-272 ◽  
pp. 1695-1699
Author(s):  
Hu Kun ◽  
Jin Yao
Keyword(s):  
Wear Rate ◽  
Contact Pressure ◽  
Sagittal Plane ◽  
Articular Surface ◽  
Wear Depth ◽  
Slip Ratio ◽  
Total Knee Replacements ◽  
Knee Replacements ◽  
Total Knee ◽  
Sliding Distance

Reducing the sliding distance by decreasing slip ratio which occur during knee articulation helps to reduce the wear rate of the ultra-high molecular polyethylene (UHMWPE) bearings in total knee replacements (TKR). However, in the limited space in knee, a smaller sagittal radius of femoral articular surface which leads to greater contact pressure that may aggravate wear is needed to make a smaller slip ratio possible. This paper described a model for evaluating the effect of slip ratio in sagittal plane on the wear depth of UHMWPE bearings. The results showed that decreasing the sagittal radius of femoral articular surface properly was an effective approach to reduce the wear of UHMWPE bearings.

Effect of Microstructure on Sliding Wear of Ca α-SiAlON Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 1253-1258 ◽  
Author(s):  
Zong Han Xie ◽  
Mark Hoffman ◽  
Robert J. Moon ◽  
P. R. Munroe ◽  
Yi Bing Cheng
Keyword(s):  
Wear Rate ◽  
Contact Pressure ◽  
Material Removal ◽  
Room Temperature ◽  
Oxidation Products ◽  
Wear Behaviour ◽  
Transgranular Fracture ◽  
Severe Wear ◽  
Pull Out ◽  
Mild Wear

The wear behaviour of Ca a-sialon ceramics of two distinct microstructures, fine equiaxed grains (EQ) and large elongated grains (EL), with the same chemical composition was investigated as a function of apparent contact pressure and sliding speed, using ball-on-disc type tribometers at room temperature and at 600°C. For room temperature tests, the EL microstructure exhibited a lower wear rate than EQ in the severe wear regime due to a greater resistance to large crack-induced material removal. As the apparent contact pressure decreased, mild wear appeared for both microstructures. The mechanism that dominated the material removal in EQ was grain pullout. In contrast, the controlling mechanism for EL was transgranular fracture. Therefore, EL had a lower wear rate than EQ in the mild wear regime. For wear tests at 600°C, crack-induced severe wear occurs in both EQ and EL samples for all contact pressures. EL had a slightly lower wear rate than EQ. Wear particles were generated on the wear track, but no tribofilm was observed and no oxidation products were detected. Wear models revealed that the grain aspect ratio plays a more important role than grain diameter in influencing the crack propagation during severe wear and grain pull-out during mild wear.

scholarly journals Parametric optimization of deep cryogenic treatment for the wear response of implant material UNS R56700: Taguchi’s approach

2019 ◽  
Vol 234 (1) ◽  
pp. 61-73
Author(s):  
Paramjit Singh ◽  
Harish Pungotra ◽  
Nirmal S Kalsi
Keyword(s):  
Wear Rate ◽  
Contact Pressure ◽  
Cryogenic Treatment ◽  
Control Variables ◽  
Deep Cryogenic Treatment ◽  
Tempering Temperature ◽  
Sliding Speed ◽  
X Ray ◽  
Morphological Alterations ◽  
Pin On Disk

Using the Taguchi’s robust design of experiments methodology, this article presents the systematic identification and optimization of most influential parameters of deep cryogenic treatment process to minimize the specific wear rate of UNS R56700 (Ti6Al7Nb). In addition to the different soaking durations (0–96 h) at 77 K and different tempering temperatures (room temperature, 403–523 K), three commonly used variables of pin-on-disk test, namely, sliding speed (1.047–2.723 ms−1), contact pressure (0.641–1.282 MPa), and sliding time (600–2280 s) were chosen to conduct the tests. During dry sliding conditions, pin-on-disk tribo-tests were performed to slide Ti6Al7Nb on the surface of UNS 52986 (En31) material as per standardized ASTM G99 guidelines. Experimentally measured wear rate values were converted to signal–noise ratio to statistically analyze the influence of five control variables using pooled analysis of variance and F-test. Statistically found influential control variables are confirmed experimentally. The results show that sliding speed, contact pressure and soaking duration are the most significant factors influencing the wear rate. In contrast, the parameters, that is, tempering temperature and sliding time, exhibit a lower level of influence. Microstructural characterizations done using optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques suggested that deep cryogenic treatment favors the refinement of grain size of present phases with reduction in β-stabilization (β-phase) in Ti6Al7Nb. The possible reasons for the improvement in wear rate of Ti6Al7Nb underlying the morphological alterations have been explained.

Ultra Mild Wear in Lubricated Tribology of an Aluminium Alloy

2007 ◽  
Vol 129 (4) ◽  
pp. 942-951 ◽  
Author(s):  
Sarmistha Das ◽  
K. Varalakshmi ◽  
V. Jayaram ◽  
S. K. Biswas
Keyword(s):  
Wear Rate ◽  
Contact Pressure ◽  
Surface Region ◽  
Measuring Instrument ◽  
Near Surface ◽  
State Of Stress ◽  
Mild Wear ◽  
Contact Mechanical ◽  
Contact Pressures ◽  
Silicon Particles

Flat faces of steel pins were slid on an eutectic aluminium silicon alloy under lubricated condition in the 1–100MPa mean contact pressure range and 0.2m∕s sliding speed. Two transition in wear rate were observed, at 10MPa and 70MPa. The wear rate in the 1–10MPa regime was found to be very small and within the measuring instrument resolution and also insensitive to contact pressure. The regime is designated ultramild wear. Lack of plastic flow, minimal fragmentation of silicon particles, and the presence of undistorted voids on the fractured and unfractured silicon particles in the subsurface suggest that the state of stress in the near surface region is elastic. Contact mechanical calculations demonstrate that at contact pressures <13.7MPa, the system is likely to shakedown to an elastic state.

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