• Title/Summary/Keyword: Wear Equation

Search Result 106, Processing Time 0.024 seconds

Analysis of Rail Wear Rate according to Wheel/Rail Contact Pressure on Curved Track (곡선부 차륜/레일 접촉압력에 따른 레일마모진전 경향 분석)

  • Sung, Deok-Yong
    • Journal of the Korean Society for Railway
    • /
    • v.20 no.4
    • /
    • pp.512-520
    • /
    • 2017
  • On a typical railway, trains travel using the friction between the wheel and the rail. Contact pressure is generated between the wheel and the rail, and the magnitude of the contact pressure changes depending on the weight, speed, wheel-set hunting, and contact point of the vehicle. In this study, the contact characteristics were analyzed through the finite element analysis for the wheel/rail system on curved track, and fatigue damage and wear rate of wheel/rail according to contact pressure were analyzed through rolling contact fatigue test. Results indicate that, general and heat treated rails showed higher wear rate than wheels, and general and heat treated rail wear rate increased rapidly over a certain number of repetitions. In addition, the general rail wear rate was about 7 ~ 15% higher than that of the heat treated rail, and a regression equation for the rail wear rate with the contact pressure in the contact pressure range of 900 ~ 1,500 MPa was presented.

A Brake Pad Wear Compensation Method and Performance Evaluation for ElectroMechanical Brake (전기기계식 제동장치의 제동패드 마모보상방법 및 성능평가)

  • Baek, Seung-Koo;Oh, Hyuck-Keun;Park, Choon-Soo;Kim, Seog-Won
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.10
    • /
    • pp.581-588
    • /
    • 2020
  • This study examined a brake pad wear compensation method for an Electro-Mechanical Brake (EMB) using the braking test device. A three-phase Interior Permanent Magnet Synchronous Motor (IPMSM) was applied to drive the actuator of an EMB. Current control, speed control, and position control were used to control the clamping force of the EMB. The wear compensation method was performed using a software algorithm that updates the motor model equation by comparing the motor output torque current with a reference current. In addition, a simple first-order motor model equation was applied to estimate the output clamping force. The operation time to the maximum clamping force increased within 0.1 seconds compared to the brake pad in its initial condition. The experiment verified that the reference operating time was within 0.5 seconds, and the maximum value of the clamping force was satisfied under the wear condition. The wear compensation method based on the software algorithm in this paper can be performed in the pre-departure test of rolling stock.

A Study of New Quick Tool-Life Testing Method (II) - The Developement a New Testing Method of Step-Cutting - (새로운 急速 工具壽命 試驗法에 관한 硏究 II)

  • 오양균;정동윤
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.11 no.1
    • /
    • pp.154-159
    • /
    • 1987
  • In the previously reported Part I, the behavior of the flank wear for carbide tool was studied as a preceeding step to present a simple method for Quick Tool-Life Testing, and the following general equation was obtained $W_{f}$ =(a+bt) $V^{m}$ . In this study the following step-cutting formula for the constants a, b and m in the above general model is derived by using step-cutting data [a numerical formula] To check the validity of the above formula, the comparison is made between the tool-life equation inferred in this method and that inferred in the conventional tool-life testing method, when the wear criterion is 0.3mm. The equation obtained in the present method is V(T')$^{0.57}$=1763 whereas the equation obtained in the conventional tool-life testing method is V(T)$^{0.56}$=1605 The results of the above two formula are satisfactory and also verify the validity of the present research.earch.

Battery Charge and Discharge Optimization for Vehicle-to-grid Regulation Service (전력 보조서비스 제공을 위한 전기자동차 충/방전 최적화)

  • Kim, Wook-Won;Shin, Hong-Yul;Kim, Jin-O;Kim, Kyu-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.63 no.8
    • /
    • pp.1033-1038
    • /
    • 2014
  • Electric vehicles should be connected to power system for charge and discharge of battery. Besides vehicle's battery is charged for a power source, it is also reversibly possible to provide power source from battery to power system. Researches on battery usage for regulation resources have been progressed and could cause cost increase excessively because they distribute regulation capacity equally without considering the battery wear cost of SOC, temperature, voltage and so on. This causes increase of grid maintenance cost and aggravate economical efficiency. In this paper it is studied that the cost could be minimized according to the battery condition and characteristic. The equation is developed in this paper to calculate the possible number of charge and discharge cycle, according to SOC level and weighting factors representing the relation between battery life and temperature as well as voltage. Thereafter, the correlation is inferred between the battery condition and wear cost reflecting the battery price, and the expense of compensation is decided according to the condition on battery wear-out of vehicle. In addition, using realtime error between load and load expectation, it is calculated how much regulation capacity should be provided.

Indirect Method for Measurement of Tool Edge Roughness in flat End Mill (평 엔드밀 공구인선부 조도의 간접적인 측정법)

  • Kim, Jeon-Ha;Gang, Myeong-Chang;Kim, Jeong-Seok
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.19 no.10
    • /
    • pp.92-98
    • /
    • 2002
  • End mill is an essential tool to generate complex surface in workpiece and it has been developed with various materials and tool shapes. The most important factor to evaluate the performance of end mill is still the wear characteristics of flank face. In addition to the flank wear, the tool edge roughness generated by the chipping is another important factor in aspects of material property and machinability evaluation and affects the quality of machined surface. Up to now, there is no direct method for measurement of tool edge roughness. In this study, the tool edge roughness of flat end mill is indirectly measured along the axial direction of workpiece. The theoretical equation is derived in consideration of tool geometry. Finally, the optimal conditions to measure the tool edge roughness by the proposed method are presented through the theoretical review and experimental identification.

A Study on Tribological Properties of Magneto-Rheological Fluid (MRF) in Polishing Process (연마공정에서 MR 유체의 트라이볼로지적 성질에 대한 연구)

  • Lee S.O.;Jang K.I.;Min B.K.;Lee S.J.;Seok J.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2006.05a
    • /
    • pp.497-498
    • /
    • 2006
  • Tribological properties of a Magneto-Rheological(MR) fluid in a polishing process are studied. For this polishing process, abrasive wear model is proposed as a function of shear force, normal force and actual mean velocity of MR particles at workpiece surface. Experimental conditions are changed by varying the gap distance between workpiece and tool and the rotational speed of tool. From the experimental results, a modified Stribeck curve is obtained, and the friction coefficient turns out to have linear relationship with a modified Sommerfeld number. The validity of the wear model is supported by additional experiments performed for measuring material removal rates.

  • PDF

Effects of self-ligating brackets and other factors influencing orthodontic treatment outcomes: A prospective cohort study

  • Jung, Min-Ho
    • The korean journal of orthodontics
    • /
    • v.51 no.6
    • /
    • pp.397-406
    • /
    • 2021
  • Objective: The purpose of this study was to evaluate the effects of self-ligating brackets (SBs) and other factors that influence orthodontic treatment outcomes. Methods: This two-armed cohort study included consecutively treated patients in a private practice. The patients were asked to choose between SBs and conventional brackets (CBs); if any patient did not have a preference, he or she was randomly allocated to the CB or SB group. All patients were treated using an identical archwire sequence. Evaluated parameters were as follows: treatment duration, number of bracket failures, poor oral hygiene, poor elastic wear, extraction, use of orthodontic mini-implants (OMI), OMI failure, American Board of Orthodontics (ABO) Discrepancy Index (DI), arch length discrepancy, and ABO Cast-Radiograph Evaluation (CRE) score. Stepwise regression analysis was performed to generate the equation for prediction of the CRE. Results: The final sample comprised 134 patients with an average age of 22.73 years. The average DI, CRE, and treatment duration were 21.81, 14.25, and 28.63 months, respectively. Analysis of covariance showed a significant difference in CRE between the CB and SB groups after adjusting for the effects of confounding variables. Stepwise regression analysis using four variables, namely extraction, SB use, poor elastic wear, and additional appliance use, could explain only 25.2% of the variance in the CRE. Conclusions: Although the CRE was significantly better for CBs than for SBs, the clinical significance of this result seems to be limited. Extraction, SB use, poor elastic wear, and additional appliance use may have significant effects on treatment outcomes.

What Promotes Adolescent Girls' Makeup in South Korea? Fashion Leadership, Social Support from Friends, and Self-Esteem

  • Sunwoo Kim;Sujin Yang
    • Journal of the Korean Society of Clothing and Textiles
    • /
    • v.47 no.2
    • /
    • pp.256-276
    • /
    • 2023
  • In South Korea, it has become popular for adolescent girls to wear makeup. From social perspectives on their makeup use, however, it remains controversial among parents, teachers, and even the girls. This study examined the status of adolescent girls' makeup usage, identified factors that influence their makeup use, and laid the groundwork for establishing a social consensus on makeup use among adolescent girls in South Korean society. Data from South Korean adolescent girls were collected and analyzed using MANOVA for repeated measures, confirmatory factor analysis, and structural equation modeling. Adolescent girls were found to wear less makeup at school than outside of school. Additionally, their makeup use was influenced by both positive (e.g., fashion leaders and social support from friends) and negative factors (e.g., low self-esteem). The findings of this study suggest that instead of strict bans against the use of makeup by girls, educational programs are needed to help adolescent girls grow up with healthy perspectives.

Development of Appeal Sizing System of Males in Their Twenties (20대 남성의 의류 치수 체계 개발)

  • 석혜정;김인숙
    • Journal of the Korean Home Economics Association
    • /
    • v.40 no.7
    • /
    • pp.157-172
    • /
    • 2002
  • The purpose of this study is to characterize body types of males in their twenties, and to provide information on body types of males by classifying them into groups. In addition, this study attempts to provide ways that can help improve the fit and coverage rate of ready-to-wear clothes by developing an apparel sizing system according to body types. 297 male subjects in their twenties participated in this study. 54 anthropometric and 35 photographic measurements were taken from each subject. After combining the body types of the front and the side into a whole body, we selected typical body types out of the combinations. It is shown that 84.64% of males in their twenties belong to the HI type, H/equation omitted/ type, X/equation omitted/ type, Xl type, Yl type, and HS type. To develop a new size system of clothes, the distribution of sizes was determined by using means and standard deviations for basic parts of each body type. Then, the most optimal sizes were selected separately for each body type to maximize the coverage rate.

A study on Contact force of Rubber Seal for wheel bearing (휠베어링 고무 실의 접촉력에 관한 연구)

  • Choi No Jin;Hur Young Min;Lee Kwang O;Kang Sung Soo
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.23 no.1 s.178
    • /
    • pp.145-151
    • /
    • 2006
  • Wheel bearing unit has been exclusively applied to car wheel supporting device. The seal for wheel bearing is required to have both high sealing effects and low reaction forces because wheel bearing are operated on adverse environmental conditions such as mud and splash water. High sealing effects are for the protection of bearing ball wear from dust influx. In order to ensure high sealing effects, it is a easiest way to increase contact force which are affected by geometric characteristics, material properties and interferences between seal and inner bearing but induces higher wear phenomena. Interferences in all variables are most important factor to determine the performance of wheel bearing. In this study, optimization of interference amount was performed with finite element analysis with commercial code ABAQUS. For the sake of finite element analysis, tensile tests of rubber material were conducted and governing equation of nonlinear behavior was achieved. Hock-up bearing was manufactured with optimized interference amount. Results of torque and mud spray tests using this bearing unit are performed. Less torque and moisture influx of bearing with optimized interference amount is evidence to validity of this study.