scholarly journals Full-Scale Dynamometer Test of Composite Railway Brake Shoes – Study on the Effect of the Reinforcing Fibre Type

2018 ◽  
Vol 12 (3) ◽  
pp. 204-208 ◽  
Author(s):  
Piotr Wasilewski
Keyword(s):  
Thermal Conductivity ◽  
Glass Fibre ◽  
Steel Fibre ◽  
Friction Material ◽  
Full Scale ◽  
Test Results ◽  
Friction Materials ◽  
Average Temperature ◽  
The Difference ◽  
Dynamometer Test

Abstract When designing or developing friction materials, it is crucial to predict how the modification of the formulation will affect their properties. Fibres are introduced in the composition of the phenolic-based brake friction materials to improve their mechanical strength. Apart from reinforcing the composite, fibres can also affect its tribological and thermophysical properties. In this study two composite friction materials are compared. The difference between the materials was the type of reinforcing fibre used in the formulation – in one case it was glass fibre, in the other steel fibre. Thermal diffusivity of both materials was measured and thermal conductivity was calculated. Frictional characteristics determined by means of full-scale dynamometer tests are analysed and discussed. Substitution of glass fibre with steel fibre led to increase in the friction coefficient. Maximum average temperature below wheel surface, observed during the test of the material containing steel fibre, was lower as compared to the test results of the material with glass fibre in its formulation, despite higher heat flux in the course of brake applications. Thermal conductivity of the friction material was enhanced by including steel fibre in the formulation.

scholarly journals COMPARATIVE STUDY ON THE EFFECT OF FIBRE SUBSTITUTION ON THE PROPERTIES OF COMPOSITE RAILWAY BRAKE SHOE

2017 ◽  
Author(s):  
P. Wasilewski ◽  
M. Kuciej
Keyword(s):  
Comparative Study ◽  
Design Process ◽  
Glass Fibre ◽  
Laboratory Tests ◽  
Friction Material ◽  
Test Results ◽  
Steel Wool ◽  
Noticeable Effect ◽  
Brake Shoe ◽  
Friction Materials

During the design process, railway friction materials are subject to extensive testing which allows for a thorough assessment of their compliance with versatile requirements and expected characteristics. These tests include, among other, laboratory tests of mechanical, physicochemical, thermophysical and tribological properties. For a designer it is crucial to understand how formulation modification influences characteristics of the friction material. One of the key ingredients in the formulation of friction materials is reinforcing fibre. In this study, two composite, organic railway brake shoes with equal amount of two different reinforcing fibres, namely steel wool and glass fibre, were tested according to the procedures of a railway friction materials manufacturer. Test results were analysed and compared. The substitution of reinforcing fibre had a noticeable effect on each of the properties of the composites considered in this study.

scholarly journals Effect of Carbonaceous Components on Tribological Properties of Copper-Free NAO Friction Material

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1163 ◽  
Author(s):  
Hsun-Yu Lin ◽  
Huy-Zu Cheng ◽  
Kuo-Jung Lee ◽  
Chih-Feng Wang ◽  
Yi-Chen Liu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Fiber ◽  
Carbon Black ◽  
Expanded Graphite ◽  
Aquatic Organisms ◽  
Friction Material ◽  
Wear Loss ◽  
Natural Graphite ◽  
Friction Materials ◽  
Artificial Graphite

Copper helps to accelerate heat transfer during the braking process, allowing the brake materials to produce a stable coefficient of friction (COF), which in turn reduces wear loss and braking noise. However, its properties are also quite harmful to aquatic organisms. Finding a suitable replacement that fits all functions of copper for brake materials is not an easy feat. In this paper, six different carbonaceous components (coke, carbon black, carbon fiber, artificial graphite, natural graphite and expanded graphite) were substituted for copper in non-asbestos organic (NAO) friction materials. The hardness, thermal conductivity and tribological behaviors of these copper-free NAO friction materials were examined. Experimental results indicate that carbonaceous components improve lubrication and assist the friction composites with generating friction layers on the worn surface. Specimens containing coke, carbon black or carbon fiber exhibit broken friction layers, whereas specimens containing artificial graphite, natural graphite or expanded graphite exhibit quite adherent and smooth friction layers. Among all the copper-free carbon containing specimens, the specimen containing expanded graphite appears to be the best choice. It has the highest thermal conductivity, a relatively low wear loss and a relatively high and stable COF.

Test and Calculation Model of Thermal Conductivity of Concrete

2022 ◽  
Vol 905 ◽  
pp. 314-319
Author(s):  
Lin Liu ◽  
Jing Chang Wang
Keyword(s):  
Thermal Conductivity ◽  
Water Content ◽  
Engineering Calculation ◽  
Calculation Model ◽  
Test Results ◽  
Hydration Degree ◽  
Plate Method ◽  
Influence Of Water ◽  
The Difference ◽  
Calculated Model

In order to study the influence of water content and hydration degree on the thermal conductivity of concrete, based on the steady-state plate method, the influence of water content, temperature, hydration degree and other factors on the thermal conductivity of early concrete was studied, and the calculation model of thermal conductivity of early concrete was established according to the test results and influence rules. The results show that there is a linear relationship between the thermal conductivity and water content at 28d, the higher the hydration degree is, the lower the thermal conductivity of concrete is; the difference between the measured value and the calculated model value is small, and the calculation formula can meet the requirements of engineering calculation.

Determining Side-by-Side Current Loads Using CFD and Model Tests

2016 ◽  
Author(s):  
Arjen Koop
Keyword(s):  
Reynolds Number ◽  
Model Test ◽  
Full Scale ◽  
Test Results ◽  
Model Scale ◽  
Moment Coefficient ◽  
The Difference ◽  
The Moment ◽  
Good Agreement ◽  
Shielding Effects

When two vessels are positioned close to each other in a current, significant shielding or interaction effects can be observed. In this paper the current loads are determined for a LNG carrier alone, a Shuttle tanker alone and both vessels in side-by-side configuration. The current loads are determined by means of tow tests in a water basin at scale 1:60 and by CFD calculations at model-scale and full-scale Reynolds number. The objective of the measurements was to obtain reference data including shielding effects. CFD calculations at model-scale Reynolds number are carried out and compared with the model test results to determine the capability of CFD to predict the side-by-side current load coefficients. Furthermore, CFD calculations at full-scale Reynolds number are performed to determine the scale effects on current loads. We estimate that the experimental uncertainty ranges between 3% and 5% for the force coefficients CY and CMZ and between 3% and 10% for CX. Based on a grid sensitivity study the numerical sensitivity is estimated to be below 5%. Considering the uncertainties mentioned above, we assume that a good agreement between experiments and CFD calculations is obtained when the difference is within 10%. The best agreement between the model test results and the CFD results for model-scale Reynolds number is obtained for the CY coefficient with differences around 5%. For the CX coefficient the difference can be larger as this coefficient is mainly dominated by the friction component. In the model tests this force is small and therefore difficult to measure. In the CFD calculations the turbulence model used may not be suitable to capture transition from laminar to turbulent flow. A good agreement (around 5% difference) is obtained for the moment coefficient for headings without shielding effects. With shielding effects larger differences can be obtained as for these headings a slight deviation in the wake behind the upstream vessel may result in a large difference for the moment coefficient. Comparing the CFD results at full-scale Reynolds number with the CFD results at model-scale Reynolds number significant differences are found for friction dominated forces. For the CX coefficient a reduction up to 50% can be observed at full-scale Reynolds number. The differences for pressure dominated forces are smaller. For the CY coefficient 5–10% lower values are obtained at full-scale Reynolds number. The moment coefficient CMZ is also dominated by the pressure force, but up to 30% lower values are found at full-scale Reynolds number. The shielding effects appear to be slightly smaller at full-scale Reynolds number as the wake from the upstream vessel is slightly smaller in size resulting in larger forces on the downstream vessel.

KARAKTERISASI KEAUSAN KOMPOSIT CANGKANG KEMIRI DAN TEMPURUNG KELAPA SEBAGAI BAHAN PEMBUATAN KAMPAS REM (BRAKE PAD)

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
Juan Randy Simamora ◽  
Chandra Kurniawan
Keyword(s):  
Data Analysis ◽  
Wear Test ◽  
Friction Material ◽  
Test Results ◽  
Brake Pad ◽  
Friction Materials ◽  
Brake Pads ◽  
Reinforcing Fibers ◽  
Coconut Shells ◽  
Shell Powder

The research has been conducted on the use of candlenut shells and coconut shells as composite materials in the manufacture of brake pads. The design of friction composite formulations is carried out based on four classes of friction material namely fillers, binders, reinforcing fibers and property modifiers with a fixed percentage based on weight. Comparison of the composition of Candlenut shell powder and coconut shell for each sample S-01 (35: 25) wt .-%, S-02 (30: 20) wt .-%, and S-03 (25: 15) wt. -%. From the results of data analysis, the values of water absorption for each sample were S-01 (0.00706%), S-02 (0.000496%), S-03 (0.00584%). The lowest wear test was found in the S-03 sample of 3.67 x 10-5 g / mm2.s. The SEM-EDS test results show the distribution of particles in different friction materials for each sample and show that carbon is present in approximately equal amounts in all formulations. The predominance of the presence of metals in brake linings includes: iron (Fe), magnesium (Mg), carbon (C), and aluminum (Al), silicon (Si), potassium (K)

Full-scale dynamometer tests of composite railway brake shoes: Effect of the resin-rubber ratio on friction performance and wear

2021 ◽  
pp. 1-16
Author(s):  
Pablo Monreal ◽  
Neil Harrison ◽  
Eduardo Perez-Costarrosa ◽  
Miguel Zugasti ◽  
Alberto Madariaga ◽  
...  
Keyword(s):  
Failure Modes ◽  
Physical And Mechanical Properties ◽  
Friction Material ◽  
Full Scale ◽  
Friction Materials ◽  
Wear Rates ◽  
Thermal Cracks ◽  
Friction Performance ◽  
Brake Block

Abstract Designing a friction material for a brake system entails considering the effects of each constituent and the interactions that they may present between them. In the present work, a characterization of the influence of the resin-rubber ratio in a brake block material is carried out. Railway brake shoes were produced and tested in a full-scale railway dynamometer in demanding conditions. The brake blocks had also their physical and mechanical properties tested. The progressive addition of resin was proven to heavily affect the friction level in dry and wet conditions. Interestingly, the use of 5% of resin showed significantly higher friction in wet conditions. This composition also presented more severe metal pick-up. The nature of the binder also affected wear rates (which were lower for lower resin contents), and the wear mechanism. The sample using only rubber presented thermal cracks and heavier delamination as specific failure modes. Differences on the microstructure of the friction materials were observed depending on the binder. A 5% of resin appears as a very interesting choice to avoid friction loss in wet environments without incurring in high wear rates, as long as metal pick-up is by different means diminished. Otherwise, a 100% of rubber as a binder grants the instantaneous friction stability that is often threaten by thermal fade.

A Modification of the Payne-Jones Method of Identifying Abnormal Differences in WISC-R Performance and Verbal IQ's

1996 ◽  
Vol 12 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Louis M. Hsu
Keyword(s):  
Full Scale ◽  
True Score ◽  
Verbal Iq ◽  
Score Difference ◽  
The Difference ◽  
And Performance

The difference (D) between a person's Verbal IQ (VIQ) and Performance IQ (PIQ) has for some time been considered clinically meaningful ( Kaufman, 1976 , 1979 ; Matarazzo, 1990 , 1991 ; Matarazzo & Herman, 1985 ; Sattler, 1982 ; Wechsler, 1984 ). Particularly useful is information about the degree to which a difference (D) between scores is “abnormal” (i.e., deviant in a standardization group) as opposed to simply “reliable” (i.e., indicative of a true score difference) ( Mittenberg, Thompson, & Schwartz, 1991 ; Silverstein, 1981 ; Payne & Jones, 1957 ). Payne and Jones (1957) proposed a formula to identify “abnormal” differences, which has been used extensively in the literature, and which has generally yielded good approximations to empirically determined “abnormal” differences ( Silverstein, 1985 ; Matarazzo & Herman, 1985 ). However applications of this formula have not taken into account the dependence (demonstrated by Kaufman, 1976 , 1979 , and Matarazzo & Herman, 1985 ) of Ds on Full Scale IQs (FSIQs). This has led to overestimation of “abnormality” of Ds of high FSIQ children, and underestimation of “abnormality” of Ds of low FSIQ children. This article presents a formula for identification of abnormal WISC-R Ds, which overcomes these problems, by explicitly taking into account the dependence of Ds on FSIQs.

Adding an expansive agent to increase the toughness of steel fibre reinforced concrete

2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan
Keyword(s):  
Reinforced Concrete ◽  
Steel Fibre ◽  
The Other ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Compressive Properties ◽  
Shrinkage Cracking ◽  
Steel Fibre Reinforced Concrete ◽  
Expansive Agent ◽  
Concrete Matrix

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.

Experimental study of the strength and durability of metal-composite high-pressure tanks

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 49-56 ◽  
Author(s):  
A. M. Lepikhin ◽  
V. V. Moskvichev ◽  
A. E. Burov ◽  
E. V. Aniskovich ◽  
A. P. Cherniaev ◽  
...  
Keyword(s):  
High Pressure ◽  
Strain State ◽  
Full Scale ◽  
Fracture Mechanisms ◽  
Metal Composite ◽  
Test Results ◽  
Stress Strain ◽  
Pneumatic Pressure ◽  
Stress Strain State ◽  
Composite Tank

The results of unique experimental studies of the strength and service life of a metal-composite high-pressure tank are presented. The goal of the study is to analyze the fracture mechanisms and evaluate the strength characteristics of the structure. The methodology included tests of full-scale samples of the tank for durability under short-term static, long-term static and cyclic loading with internal pneumatic pressure. Generalized test results and data of visual measurements, instrumental and acoustic-emission control of deformation processes, accumulation of damages and destruction of full-scale tank samples are presented. Analysis of the strength and stiffness of the structure exposed to internal pneumatic pressure is presented. The types of limiting states of the tanks have been established experimentally. Change in the stress-strain state of the tank under cyclic and prolonged static loading is considered. Specific features of the mechanisms of destruction of a metal-composite tank are determined taking into account the role of strain of the metal liner. The calculated and experimental estimates of the energy potential of destruction and the size of the area affected upon destruction of the tank are presented. Analysis of test results showed that the tank has high strength and resource characteristics that meet the requirements of the design documentation. The results of the experiments are in good agreement with the results of numerical calculations and analysis of the stress-strain state and mechanisms of destruction of the metal-composite tank.

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