scholarly journals INFLUENCE OF BORINATION, BORON CEMENTATION OF STEEL 45 AND VISCOSITY OF A LUBRICANT ON THE PARAMETERS OF ADHESION BOND IN THE STEEL 45 - 40X SYSTEM

2021 ◽  
Vol 18 (2) ◽  
pp. 67-75
Author(s):  
V.I. Kubich ◽  
◽  
◽  
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Dynamic Viscosity ◽  
Physical Modeling ◽  
Piezoelectric Coefficient ◽  
Adhesive Bond ◽  
Adhesion Bond ◽  
Twofold Increase ◽  
Additional Equipment ◽  
Relative Similarity

In the work, the regularities of changes in the shear strength of the adhesive bond τ and the piezoelectric coefficient β in the metal systems "steel 45 - 40X", "steel 45+В-40Х", "steel 45+ВС-40Х" were obtained during physical modeling of the materials I-20A, Wolf 10W-40, TAD-17i, Litol-24 with distinctive dynamic viscosities using the additional equipment of the SMTs-2 friction machine. It has been established that a twofold increase in the shear rate causes a decrease in the piezoelectric coefficient in the "steel 45+VS - 40X" system by a factor of 1.2-1.6 for Wolf 10W-40, TAD-17i, Litol-24 lubricants and its relative similarity independent of dynamic viscosity. At the same time, a twofold increase in the shear rate in the "steel 45+B-40X" system also causes a decrease in the piezoelectric coefficient by a factor of 1.16-1.38 for all tested lubricants and its alignments, as in the "steel 45+VS" system, does not observed. It was found that the clearly expressed regularity of the effect of the equivalent dynamic viscosity on the strength of the adhesive bond at p = 0 MPa is not revealed, and the nature of the manifestation is predetermined by a possible change in the mechanism of intermolecular interaction, which depends on the structure of the molecules of lubricants. It was determined that the piezoelectric coefficient naturally decreases with an increase in dynamic viscosity in the entire considered range of normal pressures.

Influence of Fillers on the Viscosity Properties of One-Pack Polyurethane Sealants

2021 ◽  
Vol 410 ◽  
pp. 605-610
Author(s):  
Kseniya A. Timakova ◽  
Yuriy T. Panov ◽  
Evgeniy A. Timakov
Keyword(s):  
Shear Rate ◽  
Dynamic Viscosity ◽  
Sharp Increase ◽  
Sharp Decrease ◽  
Shear Forces ◽  
Complex Orientation ◽  
Developed Surface ◽  
Mineral Fillers ◽  
Constant Shear Rate ◽  
Shape Of Particles

The paper investigates the effect of fillers on the viscosity properties of one-pack polyurethane sealants. It is noted that with the introduction of such mineral fillers as Mikarb, Midol, MTD2 chalk and aluminum hydroxide, the dynamic viscosity of the composition increases uniformly, while when filled with chemically precipitated Calofort SV chalk and MT-GShM talc, an abnormally sharp increase in viscosity is observed. Such an increase in viscosity for Calofort SV is explained by a highly developed surface, in contrast to other fillers. Talc is characterized by a plate-like shape of particles, which leads to a complex orientation of talc particles in the composition and shear difficulties.It was found that a sealant filled with chemically precipitated chalk has more than 100 pts. wt.(parts by weight), per 100 pts. wt. of the prepolymer under the influence of shear forces (at a constant shear rate) during the first 10 minutes of exposure, a sharp decrease in viscosity is observed, which is characteristic of thixotropic compositions, reaching a constant value after 5-10 minutes. After 10 minutes, the thixotropy of the sealant is restored. Talc does not impart thixotropic properties to the sealant composition.

scholarly journals Shear rate effect on the residual strength characteristics of saturated loess

2019 ◽  
Author(s):  
Baoqin Lian ◽  
Jianbing Peng ◽  
Qiangbing Huang
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Normal Stress ◽  
Rate Effect ◽  
Shear Tests ◽  
Residual Shear Strength ◽  
Shear Rates ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
The Difference

Abstract. Residual shear strength of soils is an important soil parameter for assessing the stability of landslides. To investigate the effect of the shear rate on the residual shear strength of loessic soils, a series of ring shear tests were carried out on loess from three landslides at two shear rates (0.1 mm/min and 1 mm/min). Naturally drained ring shear tests results showed that the shear displacement to achieve the residual stage for specimens with higher shear rate was greater than that of the lower rate; both the peak and residual friction coefficient became smaller with increase of shear rate for each sample; at two shear rates, the residual friction coefficients for all specimens under the lower normal stress were greater than that under the higher normal stress. The tests results revealed that the difference in the residual friction angle фr at the two shear rates, фr (1)–фr (0.1), under each normal stress level were either positive or negative values. However, the difference фr(1)–фr (0.1) under all normal stresses was negative, which indicates that the residual shear parameters reduced with the increasing of the shear rate in loess area. Such negative shear rate effect on loess could be attributed to a greater ability of clay particles in specimen to restore broken bonds at low shear rates.

Viscosity in Exploitation Time Analysis of the Lubricating Oil Used in the Combustion Engine of the Personal Car

2015 ◽  
Vol 220-221 ◽  
pp. 271-276 ◽  
Author(s):  
Grzegorz Sikora ◽  
Andrzej Miszczak
Keyword(s):  
Shear Rate ◽  
Dynamic Viscosity ◽  
Combustion Engine ◽  
High Shear Rate ◽  
Engine Oil ◽  
Lubricating Oil ◽  
High Shear ◽  
Oil Viscosity ◽  
Peltier Element ◽  
Engine Model

The aim of this study is to develop a mathematical model of the lubricating oil viscosity changes during the exploitation time of the engine.The aim was achieved by measurements of dynamic viscosity of engine oil used in a passenger car Volkswagen Touran equipped with a turbocharged diesel engine with a capacity of 2.0 liters. The recommended interval for oil change in this engine model is 30000 km. Oil used in this study was Shell Helix AV-L (viscosity grade SAE 5W30, designation VW: 50700).Viscosity tests were made on a Haake MARS III using two measuring systems. The first consisted of a plate-cone system with Peltier element for temperature stabilization. The second one is the high shear rate chamber with temperature control thermostat co-operating with ultra-A40 AC200 which can operate at temperatures ranging from-40 °C to +200 °C. The high shear rate chamber, consisting of a measuring cylinder and the rotor, the shear rate can achieve up to 200000 s–1.Dynamic viscosity measurements were performed at temperatures ranging from 20 °C to 90 °C.The results of the research are shown in the graphs and in tabular form. Obtained graphs made it possible to determine characteristics of the oil ageing for each mileages, temperatures and shear rates.

scholarly journals Rheological characteristics of aluminium oxide (AL2O3) based nanolubricant

2020 ◽  
Vol 39 (2) ◽  
pp. 424-432
Author(s):  
M. Ogbonnaya ◽  
O.O. Ajayi ◽  
M.A. Waheed
Keyword(s):  
Shear Rate ◽  
Exponential Function ◽  
Dynamic Viscosity ◽  
Mass Concentration ◽  
Aluminium Oxide ◽  
Al2o3 Nanoparticles ◽  
Step Method ◽  
Rheological Measurement ◽  
Linear Fit ◽  
The Relationship

This paper presents the rheological measurement of aluminium oxide (Al2O3) nanolubricant. The nanolubricant was prepared using the two-step method from dry Al2O3 nanoparticles and Capella D lubricant as base fluid. The dynamic viscosity of the Al2O3 nanolubricant at constant shear rate was measured at atmospheric pressure in the temperature range of 278 K to 323 K for pure based lubricant along with nanolubricant mass concentration of 1%, 2% and 4% with nanoparticle size of 10 nm, 20-30 nm and 80 nm. The measured data was analysed using the linear fit and exponential function fit. The result showed that at constant particle size and concentration, the dynamic viscosity reduces with increase in temperature while at constant temperature, the viscosity increased with nanoparticle concentration. The exponential function fit regression best describe the relationship between the viscosity and temperature when compared with the linear fit regression while the polynomial function fit best describe the relationship between the viscosity and mass concentration. Keywords: Dynamic viscosity, nanolubricant, shear rate, regression, concentration, temperature

scholarly journals Material Preparation and Geotechnical Properties of Transparent Cemented Soil for Physical Modeling

2021 ◽  
Vol 8 ◽  
Author(s):  
Xianlun Leng ◽  
Chuan Wang ◽  
Rong Pang ◽  
Qian Sheng ◽  
Jian Chen
Keyword(s):  
Shear Strength ◽  
Physical Modeling ◽  
Triaxial Compression ◽  
Soft Rock ◽  
Geotechnical Properties ◽  
Laboratory Model ◽  
Natural Soil ◽  
Empirical Formulas ◽  
Cemented Soil ◽  
Similar Materials

The preparation of transparent materials suitable for simulating different rock and soil masses is the foundation for image-based physical modeling tests in studying deformation and failure mechanisms in geotechnical media. A transparent cemented soil (TCS) with similar geotechnical properties of natural soil and soft rock was prepared using fused quartz as the skeleton, hydrophobic fumed silica powder as the cement and mixed mineral oil of 15# white oil and n-dodecane as the pore fluid. Eleven groups of TCS samples with different shear strengths were synthesized by adjusting the content or mass ratio of the cement and particle size or gradation of the skeleton. Contrasting tests of unconsolidated-undrained triaxial compression were carried out and the mechanical characteristics of TCS were analyzed, showing that the stress-strain relationship, shear strength and failure mode of TCS are similar to those of natural soil. The mechanical parameters of TCS undergo complex variation with the factors, and the mesoscopic mechanism of the changes therein was revealed with the help of optical microscope photos. The similarity ratio of TCS to soft rock was derived according to geometries and stress conditions of laboratory model tests, demonstrating the feasibility of using TCS as similar materials to soft rock. Moreover, empirical formulas for the change of shear strength parameters with the factors were fitted to facilitate the preparation of TCS with target shear strength in the future. The findings can provide a basis for preparing transparent similar materials to natural soil and soft rock in physical modeling tests.

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