scholarly journals Effect of Rock Abrasiveness on Wear of Shield Tunnelling in Bukit Timah Granite

2020 ◽  
Vol 10 (9) ◽  
pp. 3231
Author(s):  
Tae Young Ko ◽  
Sean Seungwon Lee
Keyword(s):  
Wear Rate ◽  
Transport Systems ◽  
Prevention Measures ◽  
Wear Coefficient ◽  
Wear Rates ◽  
Disc Cutters ◽  
Discharge Velocity ◽  
Boring Machines ◽  
Rock Abrasiveness ◽  
Slurry Shield

The abrasiveness of rocks significantly influences the wear endured by excavation tools in tunnel boring machines (TBMs). In slurry shield TBMs, wear occurs not only in excavation tools but also in discharge pipes and pumps of slurry transport systems. To explore this phenomenon, this study investigated the effect of rock abrasiveness on the wear of both disc cutters and slurry discharge pipes in slurry shield TBMs. The radial wear of disc cutters and the thickness of slurry discharge pipes were measured and monitored at a TBM site in Singapore. The relationship between the weathering grade of Bukit Timah granite and the wear coefficient of disc cutters was analysed, and a correlation between the Cerchar Abrasivity Index values and the wear coefficient of 19 inch disc cutters was suggested. Additionally, the average wear rates of slurry discharge pipes used for Bukit Timah granite were determined based on the pipe thickness measurements. The wear rates of weathering grades G(I) to G(IV) of Bukit Timah granite were observed to be highly similar to each other, whereas the wear rates of G(V) grade and mixed ground were 1.55 times higher than those of the G(I) to G(IV) grades. The correlation between the slurry discharge velocity and the wear rate in slurry discharge pipes was thus derived. The accurate assessment of the effect of rock abrasiveness on both the wear of disc cutters and the wear rate in slurry discharge pipes, investigated in this paper, will highlight the need for efficient maintenance of the excavation tools in TBMs and encourage the development of various equipment wear prevention measures in order to minimize overall construction costs and time.

Determination of Steady-State Adhesive Wear Rate

2005 ◽  
Author(s):  
L. J. Yang
Keyword(s):  
Steady State ◽  
Wear Rate ◽  
Wear Test ◽  
Standard Test ◽  
Test Method ◽  
Testing Time ◽  
Wear Coefficient ◽  
Wear Rates ◽  
Test Methodology

Wear rates obtained from different investigators could vary significantly due to lack of a standard test method. A test methodology is therefore proposed in this paper to enable the steady-state wear rate to be determined more accurately, consistently, and efficiently. The wear test will be divided into four stages: (i) to conduct the transient wear test; (ii) to predict the steady-state wear coefficient with the required sliding distance based on the transient wear data by using Yang’s second wear coefficient equation; (iii) to conduct confirmation runs to obtain the measured steady-state wear coefficient value; and (iv) to convert the steady-state wear coefficient value into a steady-state wear rate. The proposed methodology is supported by wear data obtained previously on aluminium based matrix composite materials. It is capable of giving more accurate steady-state wear coefficient and wear rate values, as well as saving a lot of testing time and labour, by reducing the number of trial runs required to achieve the steady-state wear condition.

Strategies of maintenance and repair of agricultural machinery

2020 ◽  
pp. 38-48
Author(s):  
Aleksey S. Dorokhov ◽  
Aleksandr V. Denisov ◽  
Aleksey A. Solomashkin ◽  
Valeriy S. Gerasimov
Keyword(s):  
Wear Rate ◽  
Technical Condition ◽  
Research Purpose ◽  
Agricultural Machinery ◽  
Maintenance And Repair ◽  
Wear Rates ◽  
Urgent Task ◽  
Machine Parts ◽  
Current Value ◽  
Agricultural Machines

Modern machines are subject to progressive wear that occurs at different rates, which leads to unpredictable failures that reduce the reliability and durability of machines. The strategy of maintenance and repair is aimed at eliminating these problems. (Research purpose) The research purpose is in analyzing the basic principles of the strategy of maintenance and repair of agricultural machinery in order to ensure control of the technical condition of machine parts. (Materials and methods) When resource diagnostics is used, , the allowable value of the parameter is set in advance for a part . This value is the tolerance that corresponds to a certain wear rate of the part. The tolerance is set based on the condition that if the current value of the controlled resource parameter during the next diagnosis is less than the set value, then such a part at the current value of the wear rate can be finalized until the next inter-control check. Taking into account the wear rate of the same type of parts from the group when determining the allowable wear during their resource diagnostics becomes an urgent task. (Results and discussions) As a result of research, the article presents "Methodology for determining the main indicators of reliability of parts of agricultural machines with different wear rates" and "Methodology for determining the tolerance system of parts of agricultural machines with different wear rates". (Conclusions) The article presents the tolerance system that reduces the probability of failure of machine parts in operation. During resource diagnostics, those parts whose resource parameters exceed the tolerance are rejected.

scholarly journals Sliding Wear of Conventional and Suspension Sprayed Nanocomposite WC-Co Coatings: An Invited Review

2021 ◽  
Author(s):  
R. Ahmed ◽  
O. Ali ◽  
C. C. Berndt ◽  
A. Fardan
Keyword(s):  
Wear Rate ◽  
Thermal Spray ◽  
Sliding Wear ◽  
Failure Modes ◽  
Thermal Spray Coatings ◽  
Annual Growth Rate ◽  
Total Energy Consumption ◽  
Wear Performance ◽  
Wear Rates ◽  
Spray Coatings

AbstractThe global thermal spray coatings market was valued at USD 10.1 billion in 2019 and is expected to grow at a compound annual growth rate of 3.9% from 2020 to 2027. Carbide coatings form an essential segment of this market and provide cost-effective and environmental friendly tribological solutions for applications in aerospace, industrial gas turbine, automotive, printing, oil and gas, steel, and pulp and paper industries. Almost 23% of the world’s total energy consumption originates from tribological contacts. Thermal spray WC-Co coatings provide excellent wear resistance for industrial applications in sliding and rolling contacts. Some of these applications in abrasive, sliding and erosive conditions include sink rolls in zinc pots, conveyor screws, pump housings, impeller shafts, aircraft flap tracks, cam followers and expansion joints. These coatings are considered as a replacement of the hazardous chrome plating for tribological applications. The microstructure of thermal spray coatings is however complex, and the wear mechanisms and wear rates vary significantly when compared to cemented WC-Co carbides or vapour deposition WC coatings. This paper provides an expert review of the tribological considerations that dictate the sliding wear performance of thermal spray WC-Co coatings. Structure–property relationships and failure modes are discussed to grasp the design aspects of WC-Co coatings for tribological applications. Recent developments of suspension sprayed nanocomposite coatings are compared with conventional coatings in terms of performance and failure mechanisms. The dependency of coating microstructure, binder material, carbide size, fracture toughness, post-treatment and hardness on sliding wear performance and test methodology is discussed. Semiempirical mathematical models of wear rate related to the influence of tribological test conditions and coating characteristics are analysed for sliding contacts. Finally, advances for numerical modelling of sliding wear rate are discussed.

scholarly journals The Preparation of H13 Steel for TBM Cutter and the Performance Test Close to Working Condition

2018 ◽  
Vol 8 (10) ◽  
pp. 1877 ◽  
Author(s):  
Yong Hu ◽  
Jiyu Tian ◽  
Mingxu Xu ◽  
Hongwei Zhao ◽  
Mingze Wang ◽  
...  
Keyword(s):  
Compression Strength ◽  
Performance Test ◽  
Working Condition ◽  
H13 Steel ◽  
Tunnel Boring Machines ◽  
Tunnel Boring ◽  
Disc Cutters ◽  
Boring Machines ◽  
Full Face ◽  
Tbm Cutter

The material of disc cutters is important to full-face tunnel boring machines (TBM). In recent years, disc cutters were optimized and tested by many scholars all around the world. H13(4Cr5MoSiV1) steel is widely used due to its excellent properties, especially in TBM disc cutters. In this paper, H13 steel with optimized composition was prepared and heat treatment. The high temperature compression of H13 steel was conducted at the temperatures ranging from 100 °C to 700 °C, with strain rate at 0.01 s−1. The stress-strain curves, Rockwell hardness and microstructure of H13 steel after compression were obtained and analyzed. The results showed that the compression strength and hardness decreased as the temperature increased; and the compression strength, hardness and ductility decreased rapidly between 600 °C and 700 °C, HR700 (the hardness of H13 steel at 700 °C) only reached 33.23 HRC. It is not recommended for TBM disc cutters to work in an environment over 600 °C.

Wear and osteolysis outcomes for highly cross-linked polyethylene in primary total hip arthroplasty compared with conventional polyethylene: a 15- to 18-year single-centre follow-up study

2020 ◽  
pp. 112070001989697 ◽  
Author(s):  
Nam Hoon Moon ◽  
Won Chul Shin ◽  
Min Uk Do ◽  
Suk-Woong Kang ◽  
Sang-Min Lee ◽  
...  
Keyword(s):  
Wear Rate ◽  
Survival Rates ◽  
Reoperation Rate ◽  
Volumetric Wear ◽  
Wear Rates ◽  
Total Hip ◽  
Kaplan Meier ◽  
Long Term Result ◽  
Wear Reduction

Background: Although highly positive results for wear reduction of highly cross-linked polyethylene (HXLPE) have been reported around the 10-year follow-up, the long-term result related to reoperation and wear-related survival is still an issue. Therefore, this study aimed to compare the follow-up results of a single manufacture’s polyethylene liner for >15 years in terms of survival and wear rate. Methods: This retrospective cohort study included 134 primary total hip arthroplasties (THAs) who were followed up for at least 15 years. The mean age at the time of surgery was 50.7 years (conventional polyethylene [CPE] group = 22; HXLPE group = 112). Linear and volumetric wear rates of polyethylene were measured, and the reoperation rate and radiographic osteolysis were evaluated and Kaplan-Meier survival analysis was performed in both groups. Implant-related complications were also examined. Results: HXLPE group showed a significantly lower wear rate in both linear and volumetric wear. None of the hip radiographs showed evidence of loosening or osteolysis in the HXLPE group. The survival rates at 15- to 18-year follow-up were 90.9% and 95.5% in the CPE and HXLPE groups when all-cause reoperation was the endpoint, and 90.9% and 100.0% when the wear-related reoperation was the endpoint, respectively. Implant-related complications were not different between the 2 groups. Conclusions: Wear reduction and osteolysis showed a great advantage in HXLPE after a 15-year follow-up. Although the CPE and HXLPE showed excellent survival, wear and osteolysis were more frequent in the CPE; therefore, the high risk of reoperation in the future should be considered.

A Simulation Study on the Effects of Race Surface Waviness on Cage Dynamics in High-Speed Ball Bearings

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Linkai Niu
Keyword(s):  
Wear Rate ◽  
Dynamic Model ◽  
High Speed ◽  
Wave Amplitude ◽  
Ball Bearing ◽  
Ball Bearings ◽  
Cage Effect ◽  
Surface Waviness ◽  
Slip Ratio ◽  
Wear Rates

The effects of the race surface waviness on the cage dynamics, including cage slip ratios, cage instabilities, and time-averaged cage wear rates, in high-speed ball bearings are investigated. A dynamic model of high-speed ball bearings considering the cage effect and the race surface waviness is proposed. Based on the proposed dynamic model, the effects of the maximum wave amplitude (MWA) and the wave order (WO) of race surface waviness on cage slip ratio, cage instability, and time-averaged cage wear rate are investigated. The results show that the race surface waviness has a great effect on the cage dynamics. The waviness would increase the random impacts between balls and cage pockets and thus cause more instable motion of the cage. Although the ball skidding and the cage slip ratio decrease with the increase of MWA, the cage instability and the cage wear rate become severe when MWA increases. In addition, the effect of WO on cage dynamics is nonlinear. The current investigation could provide a theoretical tool for an in-depth understanding of the dynamics in a high-speed ball bearing.

Evaluation of Wear Rate of Nanocrystalline Diamond Films Using Abbott Curve

2017 ◽  
Vol 267 ◽  
pp. 185-189
Author(s):  
Andrei Bogatov ◽  
Vitali Podgursky
Keyword(s):  
Wear Rate ◽  
Cross Sections ◽  
Vapour Deposition ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Chemical Vapour ◽  
Nanocrystalline Diamond ◽  
Wear Rates ◽  
Nanocrystalline Diamond Films ◽  
Worn Surface

The nanocrystalline diamond films were deposited by microwave plasma enhanced chemical vapour deposition (PE-CVD) on Si (100) substrate. Reciprocating sliding tests were conducted using Si3N4 balls as a counter body. A method based on the construction of the Abbott curve representing the areas of pristine and worn surface in the wear scars was applied for estimation of the wear rate. The calculated wear rates were compared with the results obtained by profilometric measurements and direct measurement of the wear scars cross sections by scanning electron microscopy (SEM).

scholarly journals Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 53
Author(s):  
Spencer Fullam ◽  
Jade He ◽  
Caroline S. Scholl ◽  
Thomas M. Schmid ◽  
Markus A. Wimmer
Keyword(s):  
Fatty Acid ◽  
Wear Rate ◽  
Conformational Change ◽  
Total Joint Replacement ◽  
Calf Serum ◽  
Competitive Binding ◽  
Wear Testing ◽  
Molar Ratio ◽  
Wear Rates ◽  
Uhmwpe Wear

Total Joint Replacement (TJR) devices undergo standardized wear testing in mechanical simulators while submerged in a proteinaceous testing solution to mimic the environmental conditions of artificial joints in the human body. Typically, bovine calf serum is used to provide the required protein content. However, due to lot-to-lot variability, an undesirable variance in testing outcome is observed. Based on an earlier finding that yellowish-orange serum color saturation is associated with wear rate, we examined potential sources of this variability, by running a comparative wear test with bilirubin; hemin; and a fatty acid, oleic acid, in the lubricant. All these compounds readily bind to albumin, the most abundant protein in bovine serum. Ultrahigh molecular weight polyethylene (UHMWPE) pins were articulated against CoCrMo discs in a pin-on-disc tribometer, and the UHMWPE wear rates were compared between lubricants. We found that the addition of bilirubin increased wear by 121%, while hemin had a much weaker, insignificant effect. When added at the same molar ratio as bilirubin, the fatty acid tended to reduce wear. Additionally, there was a significant interaction with respect to bilirubin and hemin in that UHMWPE wear rate decreased with increasing fatty acid concentration. We believe the conformational change in albumin by binding bilirubin makes it more likely to form molecular bridges between UHMWPE and the metal counterface, thus increasing adhesive wear. However, fatty acids compete for binding sites on albumin, and can prevent this conformational change. Hence, the protein is stabilized, and the chance for albumin to form bridges is lowered. Ultimately, UHMWPE wear rate is driven by the competitive binding of bilirubin and fatty acid to albumin.

scholarly journals Wear of disc mill hammer in wet grinding processes on groundnut cake for fish feed production

2016 ◽  
Vol 61 (No. 4) ◽  
pp. 162-169 ◽  
Author(s):  
O.B. Oduntan ◽  
B.O. Omitoyin
Keyword(s):  
Wear Rate ◽  
Moisture Content ◽  
Fish Feed ◽  
Screen Size ◽  
Wear Rates ◽  
Groundnut Cake ◽  
Operating Variables ◽  
Feed Production ◽  
Absolute Mass ◽  
Wear Damage

There is need to determine the wear rates of disc mill hammer used for grinding groundnut cake, a major plant protein in fish feed. This surface wear damage characterised by scoring, cutting, deep grooving and gouging on a metal surface leads to high costs of production. The hammer wear rate was carried out using disc mill for different combinations of processing conditions: disc speed of 2,175, 3,900 and 4,350 rpm; screen size of 1.0, 2.0 and 3.0 mm; moisture contents of 12, 14 and 16% w.b. at 300 operating hours. Response Surface Method was used to optimize the operating variables. The wear rate was found to increase as the moisture content of the groundnut cake decreased. Quadratic models developed for the four responses (tip length loss, width loss, thickness loss and absolute mass) studied indicated the optimum conditions at disc speed 3,262.50 rpm, screen size 2.0 mm and moisture content 14% w.b. The study established that experimental data and model predictions agreed well.

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