SLIP COEFFICIENT OF BOLTED SLIP-CRITICAL CONNECTIONS

The design philosophy of slip-critical connections is to utilize the friction force developed through the clamping force exerted by the pretension of the high-strength bolt. Therefore, the slip-critical connections can have resistance in the direction of the bolt shear. This resistance is affected by the bolt clamping force and slip coefficient on the faying surfaces. This research aims to increase the resistance of the slip-critical connections. Increasing the resistance of the slip-critical connections can be achieved by increasing either the clamping force or the slip coefficient. Thermal spray coating technology was used to increase the slip coefficient. Tests were conducted to investigate the effects of coated material (aluminum or aluminum-magnesium) and coating thickness. Compared to the blast-cleaned faying surface, thermal sprayed coating faying surface results in a greater slip coefficient.

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Exploration of novel faying surface treatment for high-strength frictional bolted joints to enhance its after-slip performance

10.2749/ghent.2021.1684 ◽

2021 ◽

Author(s):

Hitoshi Moriyama ◽

Ryo Sakura ◽

Takashi Yamaguchi ◽

Takai Toshikazu ◽

Yuta Yamamoto

Keyword(s):

Surface Treatment ◽

Load Transfer ◽

High Strength ◽

Bolted Joints ◽

Deformation Capacity ◽

Slip Coefficient ◽

Faying Surface ◽

Treatment Concepts ◽

Local Slip

<p>Welded joints is adopted rather than bolted joints for megastructure’s connections because the former can carry large force. However, the former has several problems, such as quality control of welding in situ, which the latter can solve. By contrast, as the load transfer ratio of each bolt becomes uneven proportionally to the number of bolts, local slip around extreme bolts occurs before the whole slip. Extreme bolts to which a large shear force is applied will break before other bolts. For utilizing the strength of all bolts, the problem is solved by improving shear deformation capacity in faying surface with novel surface treatment. Here, the treatment concepts were explored, and the coating’s effectiveness was evaluated through friction tests. The deformation capacity can be twice or more than that of conventional treatment, and the slip coefficient doesn’t depend on contact pressure. These features have the advantage to give stable slip behaviour.</p>

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THE EFFECT OF COATING THICKNESS ON FATIGUE PROPERTIES OF STEEL THERMALLY SPRAYED WITH Ni-BASED SELF-FLUXING ALLOY

International Journal of Modern Physics B ◽

10.1142/s0217979206040052 ◽

2006 ◽

Vol 20 (25n27) ◽

pp. 3599-3604 ◽

Cited By ~ 6

Author(s):

HIROYUKI AKEBONO ◽

JUN KOMOTORI ◽

HIDETO SUZUKI

Keyword(s):

Fatigue Strength ◽

Thermal Spray ◽

Coating Thickness ◽

Volume Fraction ◽

Steel Substrate ◽

Fatigue Cracks ◽

Spray Coating ◽

Maximum Size ◽

Thermal Spray Coating ◽

Fatigue Properties

The Thermal spraying is one of the most popular surface coating techniques. To achieve the most efficient use of this technique in practice, it is very important to clarify the fatigue properties of steel coated with a thermal spray coating. In this study, to clarify the effects of coating thickness on the fatigue properties of the steel substrate, three types of sprayed specimens with different coating thickness (0.2, 0.5 and 1.0mm) were prepared and fatigue tests were carried out. Coating thickness strongly affected the fatigue properties; the thinner the coating thickness, the higher the fatigue strength. Fatigue crack propagation behaviors were observed. Accordingly the fatigue cracks propagated through many defects on the coated surface. The sizes and number of the coating defects were determined by coating thickness; the thicker the coating thickness, the larger the defect and number. Therefore, the sprayed specimens with thinner coatings indicated higher fatigue strength. Furthermore, estimations of the fatigue strength were performed by using Murakami's equation. The fatigue strengths of thermal spray coated specimens were estimated by three parameters; (i) maximum size of coating defects estimated by statistics of extreme value, (ii) hardness of the matrix and (iii) volume fraction of coating defects.

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The Effect of WC-17Co Thermal Spray Coating By HVOF and Hard Chromium Electroplating on the Fatigue Life and Abrasive Wear Resistance of AISI 4340 High Strength Steel

Corrosion Reviews ◽

10.1515/corrrev.2003.21.1.75 ◽

2003 ◽

Vol 21 (1) ◽

pp. 75-96 ◽

Cited By ~ 10

Author(s):

Renato C. Souza,

Keyword(s):

Wear Resistance ◽

Fatigue Life ◽

Abrasive Wear ◽

Thermal Spray ◽

High Strength Steel ◽

Spray Coating ◽

High Strength ◽

Thermal Spray Coating ◽

Abrasive Wear Resistance ◽

Chromium Electroplating

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Influence of Laser-Assisted Fusing on Microstructural Evolution and Tribological Properties of NiWCrSiB Coating

Metals ◽

10.3390/met10040548 ◽

2020 ◽

Vol 10 (4) ◽

pp. 548 ◽

Cited By ~ 1

Author(s):

Changkyoo Park ◽

Eun-Joon Chun

Keyword(s):

Spray Coating ◽

Thermal Spray Coating ◽

Temperature Control System ◽

Secondary Phases ◽

Hardening Behavior ◽

Transmission Electron ◽

Transmission Electron Microscope Analysis ◽

Electron Microscope Analysis ◽

Sprayed Coating ◽

M23c6 Carbides

The present study examines the applicability of a diode laser-assisted fusing treatment and a temperature-control system to the NiWCrSiB thermal spray coating to develop the enhanced wear resistance of continuous-casting molds. As a result of the use of the lasers, the variations in the microstructure and the hardening behavior during the fusing treatment could be controlled. Fine secondary phases (approximately 0.05–10 μm in size) homogeneously present in the coating after the laser-assisted fusing were observed to be Cr-, Mo- and W-based carbides and borides. Transmission electron microscope analysis was used to characterize these fine secondary phases as M7C3 and M23C6 carbides and M5B3 boride. Because of these fine secondary phases, the hardness increased from 730 (as-sprayed status) to 1230 HV (after fusing at a temperature of 1473 K). Finally, given the formation of fine secondary phases and the occurrence of surface hardening, the laser-assisted fusing treatment was deemed to enhance the tribological performance of the thermal-sprayed coating, in that it exhibited a lower coefficient of friction and lower wear rate than the as-sprayed coating.

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The Comparison Study on Abrasive and Erosive Resistance Properties of Thermal Spray Coatings

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.901.49 ◽

2020 ◽

Vol 901 ◽

pp. 49-54

Author(s):

Jirasak Tharajak ◽

Noppakun Sanpo

Keyword(s):

Thermal Spray ◽

Thermal Spraying ◽

Spray Coating ◽

Solid Material ◽

Thermal Spray Coating ◽

Comparison Study ◽

Spray Coatings ◽

Wide Range ◽

Resistance To Wear ◽

Sprayed Coating

Thermal spraying is a technology which improves and restores the surface of a solid material. The process can be used to apply coatings to a wide range of materials and components, in order to provide resistance to wear, erosion, cavitation, corrosion, abrasion or heat. In this paper, the study of abrasive and erosive properties of Cr3C2/20%NiCr and FeCrB + Al thermal sprayed coating samples were focused. It was revealed that both received thermal spray coating samples show outstanding abrasive and erosive resistance properties.

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Elasticity Characteristics of Plasma Spray Coatings

Thermal Spray 1996: Proceedings from the National Thermal Spray Conference ◽

10.31399/asm.cp.itsc1996p0813 ◽

1996 ◽

Author(s):

L. Dekhtyar ◽

A. Kleyman ◽

S. Berman ◽

V. Andreychuk

Keyword(s):

Residual Stresses ◽

Thermal Spray ◽

Coating Thickness ◽

Quantitative Methods ◽

Spray Coating ◽

Thermal Spray Coating ◽

Spray Parameters ◽

Spray Coatings ◽

Real Value ◽

Elastic Characteristics

Abstract Future development of thermal spray processes and new composite materials raises an important problem concerning the transition from qualitative to quantitative methods of coatings evaluation. It is well known that thermal spray coating deposition in most cases is accompanied by the formation of temporal and residual stresses through the coating thickness. For proper evaluation of formed stressed state it is extremely important to know the real value of elastic characteristics in different layers of the coating. This problem has become more complicated taking into consideration the variety of materials, different spray parameters, number of coating layers and extreme service conditions. These values can be obtained only from experimentation. Elastic characteristics (EC) could be used in many calculations, such as durability, stiffness, fatigue, vibration and others. This paper describes new methods of experimental determination of elastic characteristics presumed as variable throughout the coating thickness. Influence of coating composition, particle size of initial powders, spray parameters, post-treatment and other factors on elastic modulusses were studied. Obtained experimental data for different materials supplement existing data and can be used for evaluation of residual stresses and other purposes.

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