Curve Radius

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 24666 Experts worldwide ranked by ideXlab platform

Qi Yue Liu - One of the best experts on this subject based on the ideXlab platform.

  • An Experimental Investigation on Railway Adhesion Properties under Water Medium and Dry Condition Respectively
    Advanced Materials Research, 2011
    Co-Authors: Peng Shen, Cai-yun Wang, Zhong Wen, Qi Yue Liu
    Abstract:

    The effect of wheel speed, axle load and track Curve Radius on wheel/rail adhesion properties under dry and water medium condition was investigated in this paper using JD-1 wheel/rail simulation facilities with Hertz simulation method, and then testing method of “four horizontals and three factors” was adopted to analyze the influence degree of speed, axle load and track Curve Radius on wheel/rail adhesion. Results from the experiment are that: The adhesion coefficient reached maximum at creep ratio of 1.5% under dry condition, and 1% under wet condition respectively; the adhesion coefficient under water medium condition occupy about a proportion of 32%-50% of that under dry condition. adhesion coefficient would reduce with speed increasing, axle load increasing and track Curve Radius decreasing under dry condition, and reduce with speed increasing, axle load decreasing and track Curve Radius decreasing under water medium condition; As far as influence degree of three testing factors which have effect on adhesion coefficient is concerned, axle load is the first one, then speed, finally track Curve Radius under dry condition, and speed is the first one, then axle load, finally track Curve Radius under water medium condition.

  • Numerical and Experiment Analysis of Rail Wear
    Advanced Materials Research, 2011
    Co-Authors: Cai-yun Wang, Peng Shen, Wen Zhong, Qi Yue Liu
    Abstract:

    The rolling contact wear is a severe problem and meets with much widespread interest in the world. This paper describes an numerical method and simulation experiment investigation on the rail wear affected by the Curve Radius and axle load etc. The creep force ,stick/slip areas of contact particles, and friction work of wheel/rail in static condition are analyzed by kalker’s program CONTACT. The effect of Curve Radius and axle load on rolling wear behaviour of rail is investigated by simulation experiment. The results of numerical and experiment indicates that with the decreasing of Curve Radius and the increasing of axle load, the wear value of rail increase nonlinearly, especially in the condition of the Curve Radius is less than 1200m,the wear value of rail increase rapidly. And with the decrease of Curve Radius, the maximum slippage decrease gradually, and the stick areas decrease while the slip areas increase. The growth speed of friction work of wheel/rail in the condition of smaller Curve Radius and heavier axle load is faster than in the condition of larger Curve Radius (straigth line) and lighter axle load.

  • Study on Using Numerical Method to Predict Wear Volume of Rail
    Advanced Materials Research, 2011
    Co-Authors: Cai-yun Wang, Peng Shen, Qi Yue Liu
    Abstract:

    This paper describes an numerical method and simulation experiment investigation on the rail wear affected by the Curve Radius and axle load etc. the effects of Curve Radius and axle load on The effects of axle load and Curve Radius on total slippage of contact particles and friction work of wheel/rail are investigated with numerical methods are analyzed by kalker’s program CONTACT. The effect of Curve Radius and axle load on rolling wear behaviour of rail is investigated by simulation experiment. It is indicated that axle load and Curve Radius are important factors to effect rolling contact wear of wheel-rail, and there is a linear relationship between wear volume of rail and friction work of wheel/rail; The preliminary empirical formula between wear volume of rail sample and friction work is given by analysis the experimental and calculation results, the formula offers a certain reference value for researching wear of wheel-rail and predicting wear volume of rail.

  • Study on Fatigue Crack Behavior of Rail in Different Curve Radius
    Advanced Tribology, 2009
    Co-Authors: Wen Zhong, Wenjian Wang, Qi Yue Liu
    Abstract:

    Among the rail defects, the transverse fatigue crack, which has been the most dangerous damage, is developed near the rail running face and grows perpendicular to the rail surface. Finally, the transverse fatigue crack would result in the failure of railway rail. In this paper, the rolling tests were performed using a JD-1 wheel/rail simulation facility without any lubricant. The tester is composed of a small wheel served as rail and a larger wheel served as wheel. The fatigue behavior of rail rollers with different materials and Curve Radius were investigated in detail by examining wear volume and wear scar using optical microscopy (OM) and scanning electronic microscopy (SEM). The results indicate that with Curve Radius decreasing, the wear volume of rail roller increases rapidly and the fatigue damage becomes severe. Furthermore, the cracking propagation angle increases obviously with Curve Radius decreasing and fatigue wear is dominating during the wear process. There appears distinct plastic deformation on the section of rail roller under small Curve Radius condition. For the same Curve Radius, the wear volume of PD3 rail is more than that of PG4 rail and the plastic deformation is more obvious. Moreover, the cracking propagation angle of PD3 rail material is smaller than that of PG4 rail. In conclusion, PG4 rail material is not suitable for the high-speed railway.

Huajiang Ouyang - One of the best experts on this subject based on the ideXlab platform.

H E Chenggan - One of the best experts on this subject based on the ideXlab platform.

  • effect of Curve Radius of rail on rolling contact fatigue properties of wheel steel
    Tribology, 2014
    Co-Authors: H E Chenggan
    Abstract:

    Rolling contact fatigue(RCF) and wear are inevitable problems for the infrastructure of modern railway. The effect of Curve Radius on the rolling contact fatigue properties of wheel steels under dry conditions was investigated on JD-1 wheel/rail simulation facility with Hertz contact theory and different attack angles. The rolling contact fatigue mechanism analysis of wheel with different Curve Radius was investigated in detail by observing fatigue cracks of the junction of cross section and wear surface of wheel specimens using optical microscopy and scanning electronic microscopy. The results indicate that there was an increase in the surface hardness of all specimens after testing due to work hardening. With a decrease in Curve Radius the wear volume of wheel steels increased,and the plastic flow layer became thicker and uneven, and the fatigue crack propagation of wheel steel sample intensified. Cracks continued to propagate into the bulk under alternating stress,thus creating severe fatigue damage.

Liu Qiyue - One of the best experts on this subject based on the ideXlab platform.

  • effect of Curve Radius on rolling contact fatigue properties of rails
    Journal of Southwest Jiaotong University, 2009
    Co-Authors: Liu Qiyue
    Abstract:

    The effect of Curve Radius on the rolling contact fatigue properties of PD3 and U71Mn rails was investigated on JD-1 wheel/rail simulation facility with different attack angles.The results indicate that with a decrease in Curve Radius the wear volume of rail roller increases,and the plastic flow layer becomes thicker and uneven.PD3 rail has higher wear resistance,but lower fatigue resistance,than U71Mn rail does.U71Mn rail shows an excellent anti-fatigue property.

Mee Kum Kim - One of the best experts on this subject based on the ideXlab platform.

  • Effect of base Curve Radius of therapeutic lenses on epithelial healing after laser-assisted subepithelial keratectomy
    Korean journal of ophthalmology : KJO, 2007
    Co-Authors: Je Hyun Seo, Won Ryang Wee, Jin Hak Lee, Mee Kum Kim
    Abstract:

    Laser epithelial keratomileusis (LASEK) is a surgery that corrects refractive errors to a desired level by creating a corneal epithelial flap, irradiating the exposed Bowman's layer with excimer laser, and then re-placing the flap,1,2 with the use of therapeutic contact lenses after surgery. With regards to recovery after LASEK, the scar healing process and epithelium recovery may differ depending on whether the epithelial flap survives or not. In the cases wherein the epithelial flap adheres and survives, the shedding of the epithelium's monolayer structure occurs gradually for 3-4 days after LASEK surgery, and the epithelial cells are shed to the underside of therapeutic lenses gradually.3 Generally, therapeutic contact lenses perform the role of accelerating scar healing and protecting the corneal surface mechanically as well as reducing the discomfort caused by the abnormality on the corneal surface and maintaining appropriate humidity on the corneal surface.4,5 In addition, therapeutic contact lenses have to be selected based on their appropriateness for therapy, taking into consideration the oxygen permeability, water content, raw materials, diameter, thickness, the base Curve, the peripheral Curve, the rim, and other factors.4-7 After LASEK surgery, for the corneal epithelium to recover, selection of appropriate therapeutic lenses is required. Among other factors, it is required to select the appropriate base Curve Radius since the keratometry value changes after LASEK surgery. Therefore, in our study, the effect of the base Curve Radius (BCR) on the corneal healing period after LASEK surgery was examined.

  • Clinical Performance and Fitting Characteristics With a MultiCurve Lens for Keratoconus
    Eye & contact lens, 2004
    Co-Authors: Jae Lim Lee, Mee Kum Kim
    Abstract:

    PURPOSE To evaluate the clinical outcome and fitting characteristics with a multiCurve lens for keratoconus in a Korean population. METHODS Sixty eyes with keratoconus were fit with a multiCurve lens based on topographic index and fluorescein pattern on slitlamp biomicroscopy. Three-point touch was applied in 59 eyes, and apical clearance was adopted in an eye with a persistent epithelial defect. The mean follow-up was 11.4 months. Visual acuity, comfort, glare, daily contact lens-wearing time, and the changes in topographic indices after fitting were evaluated. The relationship between base Curve Radius (BCR) and topographic indices were analyzed along with the relationship between BCR and peripheral Curve Radius. RESULTS A total of 71.6% of the eyes achieved a visual acuity of 20/30 or better. Flatter BCR was related to better visual acuity. Ninety-four percent of the patients tolerated the fitting, and 85% of them reported complete comfort. The mean daily wearing time was 11.9 hours. Four eyes reported glare. The change of Sim K during follow-up was not statistically significant. Prefitting Sim Kmax and average Sim K were significantly related to the BCR. Mean differences between the BCR and first peripheral Curve Radius were 1.06 +/- 0.21 mm with a BCR less than 6.00 mm and 0.81 +/- 0.2 mm with a BCR greater than 6.00 mm. These differences were statistically significant. CONCLUSIONS Customization with the multiCurve lens enabled patients with keratoconus to wear the contact lens comfortably and seemed not to aggravate the progression of keratoconus. Sim Kmax and the relationship between BCR and first peripheral Curve Radius seem to be useful information to optimize performance of the multiCurve lens.

Related terms

Curve Radius - 15 days free trial to Access Experts & Abstracts