scholarly journals Experimental studying the effect of water temperature on friction properties of marine propeller sliding bearing

2021 ◽  
Author(s):  
Hiep Xuan Trinh ◽  
Ngoc Bich Nguyen ◽  
Sinh Truong Nguyen
Keyword(s):  
Transition Temperature ◽  
Friction Coefficient ◽  
Water Temperature ◽  
Stress Change ◽  
Marine Propeller ◽  
Sliding Velocity ◽  
Transition Range ◽  
Sliding Bearing ◽  
Temperature Range ◽  
Polymer Bearing

This paper presents the effect of water’s temperature on the friction properties of materials used in marine propeller sliding bearing. Copper-Rubber and Copper-Capron, two common pairs of material in the shaft water-lubricated polymer bearing were chosen to conduct experiments with the pin-on-disc model. Various conditions including water temperature, stress, and sliding velocity were examined, their results showed that in the range 30 °C to 100 °C of water temperature, the frictional coefficient of both friction pairs were unchanged under the small stress and low sliding velocity (0.3 MPa and 0.9 m/s). While in the case of stress and sliding velocity were both high (0.6 MPa and 1.5 m/s), it increased significantly in a certain transition temperature range. This temperature range of the pair Copper-Rubber and Copper-Capron is 50 °C to 60 °C and 80 °C to 90 °C, respectively. The experiment’s results also pointed out that in these transition temperature ranges, the friction coefficient of two pairs was slightly influenced by the change in sliding velocity, whereas the stress change has an important impact on its values. Nonetheless, when the water temperature was below the transition range, the effect of the stress change on the friction coefficient was not significant. Thus, high water temperature is the main reason for the friction coefficient’s increase rather than the increase of the stress. This work is expected to broaden the understanding of the friction behavior of the water-lubricated polymer bearing.

Reconstitution of lipoproteins. I. Lipid–protein interaction of high density apoproteins, purified apoA-I and apoA-II with dimyristoyl-lecithin and dimyristoyl-lecithin:cholesterol vesicles studied by isomeric spin-labelled lecithins

1980 ◽  
Vol 58 (7) ◽  
pp. 581-591 ◽  
Author(s):  
D. J. Vaughan ◽  
W. C. Breckenridge ◽  
N. Z. Stanacev
Keyword(s):  
Transition Temperature ◽  
Stearic Acid ◽  
High Density Lipoprotein ◽  
Lipid Bilayer ◽  
Weight Ratio ◽  
Density Lipoprotein ◽  
High Density ◽  
Resonance Spectroscopy ◽  
Transition Range ◽  
Temperature Range

Reconstitution of high density lipoprotein-like particles from lecithin, cholesterol, and high density lipoprotein apoproteins was studied. Sonicated mixtures of sn-3-dimyristoyl-lecithin and cholesterol (molar ratio 10:1) were incubated with total human plasma high density apoproteins and purified apoprotein A-I and apoprotein A-II in the presence of isomeric (5′-, 12′-, and 16′-(N-oxyl-4″,4″-dimethyloxazolidine)stearoyl) spin-labelled lecithin probes. The supernatant obtained after centrifugation of the incubation mixture at 12 000× g for 5 min contained reconstituted lipoproteins with an average protein:lipid weight ratio of 0.52–0.53. To determine the position of apoprotein A-I and apoprotein A-II with respect to the lipid bilayer, the thermotropic behaviour of reconstituted lipoproteins was monitored by electron spin resonance spectroscopy using isomeric spin-labelled lecithin probes. Comparison of experimental spectral parameters (transition temperature, temperature range, and cooperative unit) obtained from reconstituted lipoproteins with liposomes of dimyristoyllecithin and dimyristoyllecithin:cholesterol (10:1) showed a relative increase of transition temperature and broadening of the transition range with 5- and 12-(N-oxyl-4′,4′-dimethyloxazolidine)stearic acid containing lecithin probes when reconstituted lipoproteins contained either apoprotein A-I or apoprotein A-II. With 16-(N-oxyl-4′,4′-dimethyloxazolidine)stearic acid containing lecithin probe, the transition temperatures and the temperature range relative to those values measured with 5′- and 12′-(N-oxyl-4″,4″-dimethyloxazolidine) lecithin probes were higher and narrower, respectively, with a tendency towards values obtained for liposomes not containing apoproteins. The cooperative unit in dimyristoyl-lecithin:apoprotein recombinants monitored with 5′- and 12′-(N-oxyl-4″,4″-dimethyloxazolidine) lecithin probes was smaller than or approximately equal to those measured with 16′-(N-oxyl-4″,4″-dimethyloxazolidine) lecithin probes when these systems contained either apoprotein A-I or apoprotein A-II. These and other results indicate that apoproteins A-I and A-II in lipoprotein recombinants of the composition used in our study, are partially embedded within the hydrocarbon portion of the lipid bilayer of reconstituted lipoproteins but do not span the entire lipid bilayer. Relevance of these results to the mechanism of lecithin:cholesterol acyltransferase activation is discussed.

Features of radiothermoluminescence of polypropylene and ethylene propylenediene elastomer SKEPT-4044 compositions with nanoscale metal-containing fillers

2020 ◽  
pp. 66-73
Author(s):  
A.M. Magerramov ◽  
◽  
N.I. Kurbanova ◽  
M.N. Bayramov ◽  
N.A. Alimirzoyeva ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Molecular Mobility ◽  
Fe3o4 Nanoparticles ◽  
Low Temperatures ◽  
Frost Resistance ◽  
Relaxation Processes ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Β Relaxation

Using radiothermoluminescence (RTL), the molecular mobility features in the temperature range of 77-300 K were studied for the polypropylene (PP)/ethylene propylene diene elastomer SKEPT-4044 with NiO, Cu2O and Fe3O4 nanoparticles (NPs) based on ABS-acrylonitrile butadiene or SCS-divinyl styrene matrices. It has been shown that the introduction of nanofillers in PP significantly affects the nature and temperature of γ- and β-relaxation processes, while the region of manifestation of the β-process noticeably shifts to the region of low temperatures. Composites with Cu2O NPs have a higher β-transition temperature Tβ than composites with other NPs. It was found that PP/SKEPT-4044 composites with Cu2O NPs with a dispersion of 11-15 nm and acrylonitrile butadiene thermoplastics have optimal frost resistance compared to other compositions.

Viscous Friction Effect During the Process of Tightening and Loosening of Bolted Joints

2021 ◽  
Author(s):  
Qingyuan Lin ◽  
Yong Zhao ◽  
Qingchao Sun ◽  
Kunyong Chen
Keyword(s):  
Friction Coefficient ◽  
Viscous Friction ◽  
Normal Pressure ◽  
Friction Model ◽  
Bolted Joints ◽  
Critical Parameters ◽  
Bolted Joint ◽  
Sliding Velocity ◽  
Friction Effect ◽  
Bearing Friction

Abstract Bolted connection is one of the most widely used mechanical connections because of its easiness of installation and disassembly. Research of bolted joints mainly focuses on two aspects: high precision tightening and improvement of anti-loosening performance. The under-head bearing friction coefficient and the thread friction coefficient are the two most important parameters that affect the tightening result of the bolted joint. They are also the most critical parameters that affect the anti-loosening performance of the bolted joint. Coulomb friction model is a commonly used model to describe under-head bearing friction and thread friction, which considers the friction coefficient as a constant independent of normal pressure and relative sliding velocity. In this paper, the viscous effect of the under-head bearing friction and thread friction is observed by measuring the friction coefficient of bolted joints. The value of the friction coefficient increases with the increase of the relative sliding velocity and the decrease of the normal pressure. It is found that the Coulomb viscous friction model can better describe the friction coefficient of bolted joints. Taking into account the dense friction effect, the loosening prediction model of bolted joints is modified. The experimental results show that the Coulomb viscous friction model can better describe the under-head bearing friction coefficient and thread friction coefficient. The model considering the dense effect can more accurately predict the loosening characteristics of bolted joints.

scholarly journals Preliminary results of intraspecific sterlet hybrid (Siberian sterlet × sterlet) rearing under intensive conditions

2012 ◽  
pp. 17-19
Author(s):  
Tibor Feledi ◽  
Svetlana Lengyel ◽  
András Rónyai
Keyword(s):  
Water Temperature ◽  
Growth Potential ◽  
Optimal Range ◽  
Applied Water ◽  
Early Maturation ◽  
Preliminary Results ◽  
Temperature Range ◽  
Survival And Growth ◽  
Size Heterogeneity ◽  
Intraspecific Hybrid

Due to early maturation and a small size, sterlet (Acipenserrut-henus) is a very advantageous fish for intensive sturgeon farming with regard to caviar production. According to our previous observations, the growth potential of Siberian sterlet (A.ruthenusmarsiglii) is higher than that of the European one. In our experiment, sterlet and an intraspecific hybrid (Siberian sterlet × sterlet) were tested under intensive tank conditions. During the 8 weeks of the experiment, survival, growth and size heterogeneity were investigated. According to the results, there were no significant differences in survival and growth but the size heterogeneity was higher in the hybrid. It is supposed that, in our trial, the applied water  temperature range (24.0–25.5 °C) was optimal for sterlet, but was probably above the optimal range for the hybrid.

scholarly journals Friction surface modifiers of carbon-containing material for high-temperature operation

2021 ◽  
Vol 2124 (1) ◽  
pp. 012013
Author(s):  
M N Roshchin
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Friction Coefficient ◽  
Friction Surface ◽  
Atmospheric Conditions ◽  
Temperature Range ◽  
Tribological Tests ◽  
Surface Modifiers ◽  
Antifriction Properties ◽  
High Temperature Operation

Abstract The results of high-temperature tribological tests of carbon-containing material in friction on heat-resistant stainless steel 40X13 in the temperature range from 20 to 700 °C under atmospheric conditions are presented. Friction surface modifiers “Argolon-2D” material improve antifriction properties and decrease friction coefficient value. Friction coefficient when using Ni-Se-PTFE modifier at load of 0.67 MPa and speed of 0.16 m/s is less by 5% than at speed of 0.05 m/s, and at speed of 0.25 m/s friction coefficient is less by 13% than at speed of 0.05 m/s. At 500 °C and a load of 0.67 MPa the friction coefficient when using Ni-Se-PTFE modifier is 30% higher than when using InSb-PTFE modifier, and the friction coefficient when using CuO-PTFE modifier is 1.2 times higher than when using InSb-PTFE modifier.

scholarly journals Morphology and ecology of Thalassiosira Cleve (Bacillariophyta) species rarely recorded in Brazilian coastal waters

2009 ◽  
Vol 69 (4) ◽  
pp. 1059-1071 ◽  
Author(s):  
M. Garcia ◽  
C. Odebrecht
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Water Temperature ◽  
Wide Temperature Range ◽  
Coastal Waters ◽  
Light Microscope ◽  
Temperature Range ◽  
The World ◽  
First Time ◽  
Scanning Electron

The detailed description of rarely recorded Thalassiosira species in Brazil is presented with light microscope (LM) and scanning electron microscope (SEM) illustrations. A total of 78 phytoplankton net samples (20 µm) collected between the years 2000 and 2006 in coastal waters of southern Brazilian, Cassino Beach and the estuary of Lagoa dos Patos, were studied in cleaned material using the Axiovert Zeiss LM and Jeol 6060 SEM. Water temperature and salinity of samples and six species are presented: Thalassiosira endoseriata, T. hendeyi, T. lundiana, T. minuscula, T. oceanica and T. wongii. Two species, Thalassiosira hendeyi and T. endoseriata were the most common being observed in all seasons at Cassino Beach in a wide temperature range (10-26 ºC), while only sporadically in the estuary of Lagoa dos Patos. Thalassiosira endoseriata, T. lundiana, T. oceanica and T. wongii are for the first time reported in Brazilian coastal waters. The latter two species, rarely recorded in the world, are fully illustrated based on Brazilian material.

Desirability of Tribo-Performance of Natural Based Thermoset and Thermoplastic Composites: A Concise Review

2021 ◽  
Author(s):  
Aravind Dhandapani ◽  
Senthilkumar Krishnasamy ◽  
Thitinun Ungtrakul ◽  
Senthil Muthu Kumar Thiagamani ◽  
Rajini Nagarajan ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Relative Motion ◽  
Operating Temperature ◽  
Natural Fibers ◽  
Specific Wear Rate ◽  
Thermoplastic Composites ◽  
Sliding Velocity ◽  
Concise Review ◽  
Sliding Distance

Tribology, which may be defined as an interdisciplinary subject, deals with relative motion between two or more bodies, i.e., surfaces that are interacting relatively. Thus, tribology is a science covering three vital classes, namely, 1) wear, 2) friction, and 3) lubrication. The focus of this article is to bring out the elements that are influencing the wear-resisting behavior of thermosetting and thermoplastic composites with natural-based constituents. It was also identified from the literature sources that 1) the treatments on the natural fibers acting as reinforcement and 2) the addition of fillers in resin acting as matrix could improve the wear-resisting behavior of the composites. Additionally, other conditions such as 1) sliding speed, 2) sliding velocity, 3) sliding distance, and 4) operating temperature could also influence the friction coefficient and specific wear rate of the natural-based composites.

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