Influence of corrosion on prestress strands

1999 ◽  
Vol 26 (6) ◽  
pp. 782-788 ◽  
Author(s):  
SMR Lopes ◽  
L MLP Simões
Keyword(s):  
Mechanical Properties ◽  
Coefficient Of Friction ◽  
Prestressed Concrete ◽  
Surface Condition ◽  
Fatigue Properties ◽  
Structural Members ◽  
The Coefficient Of Friction ◽  
Bond Characteristics ◽  
Beams And Girders ◽  
Prestressed Beams

Corrosion on prestress strands affects their mechanical properties as well as the coefficient of friction in the surface strand/duct. In previous research on prestress beams, the authors have observed different coefficients of friction depending on the surface condition of the strands and wires used in investigation. Some of the strands used for the experiments were stored for some months in the laboratory and gained some rust on the surface. This was enough to influence the coefficient of friction in a noticeable manner. To study the influence of corrosion on the mechanical properties of prestress strands several samples were stored under different environmental conditions to produce various levels of corrosion. These samples were tested afterwards to determine the influence of corrosion on fatigue properties and the coefficient of friction. Apart from the coefficient of friction, light rust decreases none of the other studied mechanical properties of the strands and may even increase the bond characteristics. The presence of rust does not necessarily mean that the strands should be rejected. The work described in this paper was conducted to investigate the level of rust that could be considered acceptable and how corrosion influences some mechanical properties of prestressing strands.Key words: reinforced concrete, prestressed concrete, prestressed beams and girders, structural design, structural members, corrosion, fatigue, losses.

scholarly journals МОДЕЛЮВАННЯ ПРОЦЕСУ ТЕРТЯ В ТЕКСТИЛЬНИХ МАТЕРІАЛАХ

2020 ◽  
Vol 144 (2) ◽  
pp. 45-53
Author(s):  
Н. П. Супрун ◽  
М. Л. Рябчиков ◽  
І. О. Іванов
Keyword(s):  
Mechanical Properties ◽  
Coefficient Of Friction ◽  
Textile Material ◽  
Structural Elements ◽  
Friction Process ◽  
Textile Materials ◽  
Factors Influencing ◽  
The Coefficient Of Friction ◽  
Properties Of Materials ◽  
Main Factors

Create a model for determining the coefficient of friction of textile materials to identify the main factors influencing the process of friction, taking into account the structural and mechanical properties of materials. Modeling of friction process in textile materials as a combination of adhesive and elastic phenomena. Roughness of solid bodies and the main parameters of roughness, such as the height of micro-irregularities, their pitch, sharpening, etc. described in many standards and scientific papers. However, the modeling of the friction process in such systems is very complicated due to the irregularity of distribution of microroughness. The analysis of literature data showed that the surface roughness of textile materials is an important and effective factor in predicting the tactile properties of products for various purposes. Estimation of surface roughness is usually carried out using subjective and objective methods, and the latter can be contact and non-contact. The paper develops a model for determining the coefficient of friction of textile materials to identify the main factors influencing the friction process, taking into account the structural and mechanical properties of materials. Friction force is presented as a combination of two main factors. The first is the elastic resistance to deformation, the second is the adhesive resistance to compression of the structural elements of the material. The main parameters influencing the coefficient of friction of textile fabrics - modulus of elasticity of structural elements, their geometrical parameters - surface density of textile material, linear density of structural elements are established. The obtained results allow to qualitatively predict the friction forces of a textile material with known parameters of its structural elements, as well as to normalize these parameters to create materials with specified friction indices. The obtained results make it possible to select the threads that form the textile material, according to the values of the modulus of elasticity, thickness, location density to ensure the minimum friction force.

Morphological Characteristics and Physical & Mechanical Properties of seeds of small-seeded crops

2020 ◽  
pp. 27-35
Author(s):  
Elchyn Aliiev ◽  
◽  
Christina Lupko ◽  
Keyword(s):  
Mechanical Properties ◽  
Coefficient Of Friction ◽  
Morphological Characteristics ◽  
Physical And Mechanical Properties ◽  
Specific Weight ◽  
Test Material ◽  
Effective Diameter ◽  
Morphological Parameters ◽  
Separation Processes ◽  
The Coefficient Of Friction

To create a database and systematize the seeds of samples of small-seeded crops, it is necessary to determine the patterns of influence of morphological parameters on their physical and mechanical properties. The development of the latest technologies and technical devices for cleaning and separation is possible due to the understanding of the characteristic morphological parameters for each of the small-seeded crops. The aim of the research is to determine the physical and mechanical properties of the seed material of small-seeded crops (mustard, flax, ryegrass, rapeseed), necessary to increase the efficiency of their cleaning and separation processes. To achieve this goal, a plan of experimental research was developed, which provided for the determination of physical and mechanical parameters of seeds of small-seeded crops, namely: indicators that characterize the flowability of seeds (angle of natural bias); frictional properties of seeds (static coefficient of friction); porosity (density) and density; size and mass characteristics of seeds (length, width, thickness, effective diameter, weight of 1000 seeds). It is established that the physical and mechanical properties of seeds of small-seeded crops are greatly influenced by its humidity. With increasing humidity, the performance of the test material increases. This is due to the fact that with increasing humidity, the shape of the seed almost turns into a spherical, which, in turn, leads to an increase in the curvature of the surface and reduce the points of contact between the seeds. As a result, the angle of natural inclination increases. The coefficient of friction of seeds of small-seeded crops depends on the roughness of the friction surface and decreases with increasing humidity. This is due to the fact that with increasing humidity decreases the forces of molecular attraction of the seed coat to the surface of the material. Seed density increases with increasing humidity. From this we can conclude that the absorption of moisture by the investigated material increases the total weight of the seed, and as a result - increases its specific weight.

Simulating the Mechanical Properties of a Yarn Based on the Properties and Arrangement of its Fibers Part II: Results of Simulations

1997 ◽  
Vol 67 (5) ◽  
pp. 342-347 ◽  
Author(s):  
Lieva Van Langenhove
Keyword(s):  
Mechanical Properties ◽  
Theoretical Model ◽  
Coefficient Of Friction ◽  
Stress Strain ◽  
Fiber Property ◽  
The Coefficient Of Friction ◽  
Predicted Values

Part I established a theoretical model that was able to predict the stress-strain and torque-strain curves of a yarn. This second part evaluates the model. The influence of fiber and yarn parameters on the predicted values is also discussed. The most critical fiber property is the coefficient of friction.

Effect of Copper on the Friction Properties of Gray Cast Iron

2014 ◽  
Vol 698 ◽  
pp. 364-368 ◽  
Author(s):  
Natalia Stepanova ◽  
Elena Lozhkina ◽  
Alexey Razumakov
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Coefficient Of Friction ◽  
Copper Content ◽  
Gray Cast Iron ◽  
Gray Cast ◽  
The Coefficient Of Friction ◽  
Effect Of Copper ◽  
20 Nm

The structure and mechanical properties of gray cast iron with a copper content of from 0.08 to 14.7 wt. % is investigated. Inclusions of ε-copper ranging from 20 nm to 240 microns are formed in the structure with an content of Cu and 0,9 % Al 14,7 % Cu. Increasing a copper content in iron results in increasing the microhardness of pearlite and reducing the coefficient of friction

scholarly journals Optimization of Mechanical Properties of Cr3C2-Ni20Cr/Graphite Cold Sprayed Coatings

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3458
Author(s):  
Wojciech Żórawski ◽  
Anna Góral ◽  
Medard Makrenek ◽  
Dominika Soboń ◽  
Anna Trelka ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Coefficient Of Friction ◽  
Solid Lubricant ◽  
Gas Composition ◽  
Graphite Content ◽  
Process Gas ◽  
The Coefficient Of Friction ◽  
Parameter Values ◽  
Sprayed Coatings ◽  
Friction Analysis

This study analyzed the mechanical properties of cold-sprayed Cr3C2-25(Ni20Cr) blended with Ni-graphite as a solid lubricant deposited on 7075 aluminum alloy substrate. To optimize the coating properties, different sets of parameters (graphite content in feedstock, process gas composition, spraying distance, and traverse gun speed) were tested in the frame of the Taguchi experiment. The cold-sprayed coatings were evaluated for their chromium carbide and graphite content, hardness, and coefficient of friction. Analysis of the microstructure of the deposited coatings revealed that graphite as a soft and brittle component fills all voids in the coating and its quantity depends on its content in the feedstock. The experimental results show that the composition of the process gas has the greatest impact on the Cr3C2 content in the coating and the proportion of graphite in the sprayed blend directly affects its hardness. In the case of the coefficient of friction, the most significant parameters were the graphite content in the sprayed blend, the spraying distance, and process gas composition. The conducted verification experiment with the optimum parameter values allowed a coating with the highest hardness and the lowest coefficient of friction to be obtained.

Mechanical Properties of Aluminium Matrix Composites Reinforced with Glassy Carbon Particles

2011 ◽  
Vol 176 ◽  
pp. 39-48 ◽  
Author(s):  
Jerzy Myalski ◽  
Józef Śleziona
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Coefficient Of Friction ◽  
Glassy Carbon ◽  
Friction And Wear ◽  
Matrix Composites ◽  
Carbon Particles ◽  
Small Influence ◽  
The Coefficient Of Friction ◽  
Reinforcement Value

The mechanical properties of composite materials with glassy carbon (GC) have been presented. The effect of size and reinforcement value on tensile strength, impact and tribological characteristics (coefficient of friction and wear) were estimated. It has been found that the reinforcement value decide on mechanical properties. Enlargement of particles value leads to decreasing of tensile strength and impact strength. It has been shown that particle size has small influence on studied properties. Destruction energy for the composites with particles exceeding 100 µm is similar. The measurement of coefficient of friction proved, that increase of reinforcement value leads to decreasing of coefficient of friction from 0.4 for 5% value to about 0.12 for 20% of particle value. The coefficient of friction is comparable for the composites containing particles of 200 µm size and is less dependent on reinforcement value. However size of the particles decide on the character of coefficient of friction changes.

scholarly journals Influence of Heat Treatment and the Coefficient of Friction on the Volume of Metal Removed During Grinding Steel 35

2015 ◽  
Vol 2 ◽  
pp. 72
Author(s):  
Igor Nikiforov ◽  
Pavel Maltsev
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Physical And Mechanical Properties ◽  
Abrasive Grain ◽  
Coefficient Of Sliding Friction ◽  
The Coefficient Of Friction ◽  
Relative Change

The role of external friction and chip contraction during microcutting by abrasive grain is showed. The method for determining the relative change in the coefficient of friction during grinding is proposed. The hypothesis about the influence of physical and mechanical properties and microstructure of steel 35 on the volume removes metal through the change in the coefficient of sliding friction of the chip by face of the abrasive grain is experimentally proved.

scholarly journals Study of tribological properties of epoxy and resins composites under technically dry friction conditions

2018 ◽  
Vol 19 (12) ◽  
pp. 658-661
Author(s):  
Sylwester Stawarz ◽  
Magdalena Stawarz ◽  
Robert Gumiński ◽  
Wojciech Kucharczyk
Keyword(s):  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Dry Friction ◽  
Friction And Wear ◽  
Surface Condition ◽  
Selective Transfer ◽  
X Ray ◽  
Tribological Tests ◽  
Transfer Phenomenon ◽  
The Coefficient Of Friction

The article discusses the results of tribological tests of epoxy and resol composites. There was examined the surface condition of samples of composites operating in sliding nodes. It has been found that it is possible to use cheaper resole resins for sliding composites (instead of Epidian 5). Tests that have been carried out showed that increasing the PTFE content in the composite resulted in lowering both the coefficient of friction and wear. X-ray analysis results con-firmed the occurrence of the selective transfer phenomenon

scholarly journals The Effect of Annealing Temperatures on Selected Properties of WC/C Coatings, Deposited Using Hexacarbonyl Wolfram in an N2-SiH4 Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4658
Author(s):  
Peter Horňák ◽  
Daniel Kottfer ◽  
Karol Kyzioł ◽  
Marianna Trebuňová ◽  
Mária Kaňuchová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Chemical Vapor Deposition ◽  
Chemical Composition ◽  
Coefficient Of Friction ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Protective Atmosphere ◽  
Annealing Temperatures ◽  
The Coefficient Of Friction

In this paper, we present the results of an experimental study on WC/C coatings, deposited by using plasma-enhanced chemical vapor deposition in an N2-SiH4 atmosphere, annealed at temperatures of 200, 500 and 800 °C, in which the hexacarbonyl of W was used as a precursor. During the experiments, the topography, chemical composition, morphology, as well as selected mechanical properties, such as hardness, Young’s modulus, and coefficient of friction of the WC/C coatings were analyzed. Annealing without the protective atmosphere in the mentioned temperatures caused a decrease in hardness (up to 15 ± 2.7 GPa). In addition, the coefficient of friction value increased only to 0.37 ± 0.03.

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