• Tribology and Lubricants
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• v.39 no.6
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• pp.235-243
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• 2023

This paper presents the fabrication process of water-lubricated plastic bearings. Plastic bearings require good mechanical properties and tribological properties as well as elasticity and shock resistance, especially when lubricated in dirty water conditions. In this study, sleeve-type plastic bearings are produced by winding a prepreg sheet, which primary contains nitrile rubber (NBR)-modified epoxy, self-lubricating fillers, and various types of lattice-structured reinforcing fibers such as carbon, Aramid, and polyethylene terephthalate. A thermosetting epoxy is chemically modified with NBR to impart elasticity and low-friction characteristics in water conditions. Experimental investigations are conducted to examine the mechanical and tribological characteristics of the developed bearing materials, and the results are compared with the characteristics of a commercial plastic bearing (Thordon SXL), well known as a water-lubricated bearing. A Thordon bearing (mainly composed of polyurethane) exhibits an extremely low load-bearing capacity and is thus only suitable for medium loading (1~10MPa). The tribological characteristics of the test materials are evaluated through Falex block-on-ring (LFW-1) friction and wear tests. The results indicate that friction exhibited by the carbon-fiber-reinforced NBR-10wt.%-modified epoxy composite material, incorporated with the addition of 20wt.% UHMWPE and 6wt.% paraffin wax, is lower than that of the Thorden bearings, whereas its wear resistance surpass that of Thorden ones. Because of these features, the load carrying capacity of the fabricated composite (>10MPa) is higher than that of the Thorden bearings. These results confirm the applicability of water-lubricated plastic bearing materials developed in this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.69-78
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• 2008

In this study, in order to verify the reinforcement effects of the cracked concrete tubes and culverts, static load test was conducted. After the load carrying capacity of the original concrete tubes (nominal diameter 0.8 m, 1.0 m, 1.5 m) and box culverts (inner width 2.0 m. 2.5 m) was reduced by the cracking test, the cracked concrete specimens were strengthened by installing profile with steel stiffener and high strength mortar. And then, the maximum load tests were conducted the renewal concrete tubes and box culverts. According to the method application, the load carrying capacity increased 1.66~3.50 times than it of the original tubes before applying the method. In case of the original box culverts, the load carrying capacity increased 1.66~3.10 times than the case before installing profile and high strength mortar. Also non-linear analysis was carried out by using the commercial FEM program of ABAQUS 6.6. Solid (C3D8R) elements and concrete damage plasticity option was applied to the analysis. For reflecting confined reinforcing bars in the analysis, the composite material properties were used.