Investigation of the Rheokinetic Properties and Penetration Depth of Aluminosilicate Adhesive in Pine Wood

2021 ◽  
Vol 321 ◽  
pp. 97-103
Author(s):  
Sergii G. Guziy ◽  
Olena Guzii ◽  
Vasyl Lashchivskiy
Keyword(s):  
Phase Particle ◽  
Adhesive Layer ◽  
Shear Stresses ◽  
Wood Substrate ◽  
Depth Of Penetration ◽  
Dispersion Phase ◽  
Shear Rates ◽  
Relative Shear ◽  
Speed Range ◽  
Binder Composition

Practical work and is devoted to the study of the rheological and deformative properties of Geofip aluminosilicate glue, obtained on the basis of an alkaline aluminosilicate binder composition Na2O Al2O3×6SiO2×20H2O, modified with 5% Cr2O3, when gluing wooden trusses in the field. The rheological and deformative properties of an aluminosilicate adhesive based on an alkaline aluminosilicate binder composition of Na2O×Al2O3×6SiO2×20H2O modified with 5% Cr2O3 have been investigated. It is noted that the dynamic viscosity of the adhesive slurry in the speed range from 0.1 to 0.8 RPM varies from 147600 to 144600 cP, and the average plastic viscosity in the same speed range is 87.39 cP. It was found that at shear rates from 0.021 to 0.168 1/s, an increase in shear force from 31 to 242.9 dyne/cm2 is observed due to the stabilization and uniformity of the dispersion phase particle distribution in the dispersion medium of the adhesive. It is shown that the aluminosilicate adhesive at a surface tension value of 88.1 mN/m is characterized by coefficients of wetting (s = 0.648) and fluidity (f = -62.02 mN/m), which ensures the uniformity of its application to the pine substrate. The average thickness of the adhesive layer was 1.25 mm, and the average depth of penetration of the aluminosilicate adhesive into the wood substrate, respectively, 0.12 mm. The destruction of the adhesive seam occurred at shear stresses of 515 MPa. The relative shear deformations were 162.5×10-5 mm.

scholarly journals Effects of posture on shear rates in human brachial and superficial femoral arteries

2008 ◽  
Vol 294 (4) ◽  
pp. H1833-H1839 ◽  
Author(s):  
S. C. Newcomer ◽  
C. L. Sauder ◽  
N. T. Kuipers ◽  
M. H. Laughlin ◽  
C. A. Ray
Keyword(s):  
Shear Rate ◽  
Femoral Artery ◽  
Brachial Artery ◽  
Superficial Femoral Artery ◽  
Upright Posture ◽  
Brachial Artery Diameter ◽  
Shear Rates ◽  
Femoral Arteries ◽  
Lower Shear ◽  
Relative Shear

Shear rate is significantly lower in the superficial femoral compared with the brachial artery in the supine posture. The relative shear rates in these arteries of subjects in the upright posture (seated and/or standing) are unknown. The purpose of this investigation was to test the hypothesis that upright posture (seated and/or standing) would produce greater shear rates in the superficial femoral compared with the brachial artery. To test this hypothesis, Doppler ultrasound was used to measure mean blood velocity (MBV) and diameter in the brachial and superficial femoral arteries of 21 healthy subjects after being in the supine, seated, and standing postures for 10 min. MBV was significantly higher in the brachial compared with the superficial femoral artery during upright postures. Superficial femoral artery diameter was significantly larger than brachial artery diameter. However, posture had no significant effect on either brachial or superficial femoral artery diameter. The calculated shear rate was significantly greater in the brachial (73 ± 5, 91 ± 11, and 97 ± 13 s−1) compared with the superficial femoral (53 ± 4, 39 ± 77, and 44 ± 5 s−1) artery in the supine, seated, and standing postures, respectively. Contrary to our hypothesis, our current findings indicate that mean shear rate is lower in the superficial femoral compared with the brachial artery in the supine, seated, and standing postures. These findings of lower shear rates in the superficial femoral artery may be one mechanism for the higher propensity for atherosclerosis in the arteries of the leg than of the arm.

Effects of Flow Properties of Lithium Soap Greases on Bearing Torque

2019 ◽  
Vol 823 ◽  
pp. 123-127
Author(s):  
Norifumi Miyanaga ◽  
Mitsumi Nihei ◽  
Jun Tomioka
Keyword(s):  
Apparent Viscosity ◽  
Small Amplitude ◽  
Shear Stresses ◽  
Flow Properties ◽  
Small Amplitude Oscillatory Shear ◽  
Small Ball ◽  
Shear Rates ◽  
Lithium Soap ◽  
Viscoelastic Behaviors ◽  
Plate Type

This study describes the influence of flow properties of lithium soap greases on torque of small ball bearings. Three types of greases with different worked penetration were tested in this study. Their rheological properties are revealed by a cone plate type rheometer. Shear stresses under various shear rates are fitted with the Herschel-Bulkley equation. In addition, viscoelastic behaviors of the greases are measured by small amplitude oscillatory shear. The crossover stress that means the shear stress at G’=G” is obtained for the greases. Then, the bearing torque when three types of greases are used as a lubricant is measured. As the results, the grease with higher crossover stress shows the lower bearing torque regardless of that it has larger apparent viscosity. On the other hand, the grease with lower crossover stress shows the higher bearing torque regardless of that it has lower apparent viscosity. These results imply that the channeling state appears in the grease with higher crossover stress while the churning state appears in the grease with lower crossover stress.

Analysis of the Bearing Capacity of Adhesive Joint of Honeycomb Cores of Sandwich Structures with the Continuous Adhesive Layer

2020 ◽  
Vol 864 ◽  
pp. 228-240
Author(s):  
Andrii Kondratiev ◽  
Oksana Prontsevych ◽  
Tetyana Nabokina
Keyword(s):  
Bearing Capacity ◽  
Adhesive Joint ◽  
Sandwich Structures ◽  
Adhesive Layer ◽  
Honeycomb Structure ◽  
Bonding Process ◽  
Aluminium Foil ◽  
Honeycomb Core ◽  
Technological Parameters ◽  
Depth Of Penetration

Adhesive sandwich structures with the honeycomb core of the metallic foil, polymeric papers and composites are widely and effectively used in the units of aerospace engineering and in the other industries owing to a number of undeniable advantages, including high specific strength and stiffness. In the process of designing and manufacturing of abovementioned structures, it is necessary to ensure high strength and reliability of the adhesive joint of the bearing skins and honeycomb core at a small area of their contact. The decisive factors influencing the bearing capacity of such joint are the technological parameters of the bonding process. Using the finite element modeling, the paper deals with the bearing capacity of the adhesive joint of bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex at transversal tearing for the key factors of the bonding process. The pattern of the adhesive joint failure (on the adhesive of honeycombs) has been revealed, depending on the depth of penetration of honeycombs ends in the adhesive, physical and mechanical characteristics of honeycombs, modulus of elasticity and tearing strength of the adhesive and thickness of the adhesive layer. Peculiar features of behavior of adhesive joints of the bearing skins with the honeycomb core based on the aluminium foil and polymeric paper Nomex under the load have been established, which should be taken into account in designing and manufacturing of honeycomb structures. The recommendations are given with regard to choosing of parameters of the process of honeycomb structure bonding, which allow providing with the acceptable accuracy the optimal depth of penetration of ends of the honeycomb core faces in the adhesive layer of specified depth.

Effects Of Short Time High Shear Exposure Upon Platelet Function And The Coagulation System Under Heparin Anticoagulation

1981 ◽  
Author(s):  
L J Wurzinger ◽  
R Opitz ◽  
P Blasberg ◽  
K Bialonski ◽  
H Schmid-Schönbein
Keyword(s):  
Platelet Function ◽  
Lactic Dehydrogenase ◽  
Arterial Stenosis ◽  
Coagulation System ◽  
Shear Stresses ◽  
High Shear ◽  
Platelet Factor ◽  
Shear Rates ◽  
Heparin Anticoagulation ◽  
Short Time

The fact that high shear activates and damages platelets has been suspected to be a major cause of thromboembolism in artificial internal organs (AIO) or in arterial stenosis. In AIO wall shear stresses well above 50 Nm-2 have been computed to which blood cells are exposed for times in the order of milliseconds (ms). Unfortunately, the studies on this subject employing defined flow conditions operate with exposure times higher than 10 seconds. The pupose of the present study was to elucidate the effects of high shear exposure for ms upon platelet function (ADP induced platelet aggregation (PA), platelet procoagulant activity {PF- 3)) under heparin anticoagulation, which is also used in AIO.To apply shear rates ranging from 50 - 220 Nm-2 to heparinized PRP for defined exposure times between 7 - 700 ms a flow through Couette-viscometer was employed. Platelet factor 3 (PF-3) availability was estimated by using a modified Stypven time technique. Lactic dehydrogenase (LDH) liberation was taken as a measure for platelet destruction. All steps of the experimental procedure were carried out at 37°C.From our data we conclude that, in the presence of physiological calcium levels (heparin anticoagulation) shear stresses and exposure times that certainly occur in AIO are able to activate platelets and procoagulant potential of blood.

Rheology of Fluoride Gels

1976 ◽  
Vol 55 (3) ◽  
pp. 353-356 ◽  
Author(s):  
M. Braden ◽  
Ratna Perera
Keyword(s):  
Infrared Spectroscopy ◽  
Shear Rate ◽  
Elastic Behavior ◽  
Shear Stresses ◽  
High Shear ◽  
Shear Rates ◽  
Extreme Stress ◽  
Thickening Agents ◽  
Shear Rate Dependence ◽  
Low Shear

Six commercial fluoride gels have been studied, using a cone and plate viscometer. Also, the thickening agents have been analyzed using infrared spectroscopy. All gels showed stress thinning, which is the decrease of viscosity with shear rate. Such shear rate dependence is clinically convenient in that the gel will flow readily at the high shear stresses present when the gel is applied but will not flow readily under its own weight when on the tooth. Five materials containing hydroxyalkyl celluloses showed similar degrees of shear thinning. One material with a non-cellulosic thickener showed much more extreme stress thinning together with elastic behavior at low shear rates; such behavior may be clinically advantageous. All of the gels showed only slight temperature dependence of rheological properties.

Free Asymmetric Vibrations of Composite Full Circular Cylindrical Shells Stiffened by a Bonded Central Shell Segment

2004 ◽  
Author(s):  
U. Yuceoglu ◽  
V. O¨zerciyes
Keyword(s):  
Cylindrical Shell ◽  
Shell Theory ◽  
Natural Frequencies ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Adhesive Layer ◽  
Shear Stresses ◽  
First Order ◽  
Stress Resultant ◽  
Circular Cylindrical Shells

This study is concerned with the “Free Asymmetric Vibrations of Composite Full Circular Cylindrical Shells Stiffened by a Bonded Central Shell Segment.” The base shell is made of an orthotropic “full” circular cylindrical shell reinforced and/or stiffened by an adhesively bonded dissimilar, orthotropic “full” circular cylindrical shell segment. The stiffening shell segment is located at the mid-center of the composite system. The theoretical analysis is based on the “Timoshenko-Mindlin-(and Reissner) Shell Theory” which is a “First Order Shear Deformation Shell Theory (FSDST).” Thus, in both “base (or lower) shell” and in the “upper shell” segment, the transverse shear deformations and the extensional, translational and the rotary moments of inertia are taken into account in the formulation. In the very thin and linearly elastic adhesive layer, the transverse normal and shear stresses are accounted for. The sets of the dynamic equations, stress-resultant-displacement equations for both shells and the in-between adhesive layer are combined and manipulated and are finally reduced into a ”Governing System of the First Order Ordinary Differential Equations” in the “state-vector” form. This system is integrated by the “Modified Transfer Matrix Method (with Chebyshev Polynomials).” Some asymmetric mode shapes and the corresponding natural frequencies showing the effect of the “hard” and the “soft” adhesive cases are presented. Also, the parametric study of the “overlap length” (or the bonded joint length) on the natural frequencies in several modes is considered and plotted.

scholarly journals Compression Shear Properties of Adhesively Bonded Single-Lap Joints of C/C Composite Materials at High Temperatures

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1437 ◽  
Author(s):  
Yanfeng Zhang ◽  
Zhengong Zhou ◽  
Zhiyong Tan
Keyword(s):  
Composite Materials ◽  
Adhesive Layer ◽  
Lap Joints ◽  
Experimental Result ◽  
Shear Stresses ◽  
Test Results ◽  
Adhesively Bonded ◽  
Finite Element Software ◽  
Joint Structure ◽  
Simulation Results

The performance of joint structure is an important aspect of composite material design. In this study, we examined the compression shear bearing capacity of the adhesively bonded single-lap joint structure of high-temperature-resistant composite materials (C/C composite materials). The test pieces were produced in accordance with the appropriate ASTM C1292 standard, which were used for the compression shear test. The failure morphology of the layer was observed by a digital microscopic system and scanning electron microscope. The experimental result shows that the load on the test piece increased nonlinearly until the failure occurred, and most of the adhesive layer exhibited cohesive failures at three temperature points (400, 600, and 800 °C), while the interface failures occurred in a small part of the adhesive layer. A numerical analysis model was established using ABAQUS finite element software. The simulation results were compared with the test results to verify the correctness of the model. On the basis of correctness of the model verified by comparing the simulation results and the test results, the influences of temperature and overlapped length on the joint compression shear performance were studied through the validated simulation method. Numerical results showed that the ultimate load of the joint decreased with increases in temperature and that the distribution trends of the shear stresses in the overlapped length direction were substantially the same for joints of different overlapped lengths.

Frictional anisotropy in nonmetallic crystals

1966 ◽  
Vol 295 (1442) ◽  
pp. 244-258 ◽  
Keyword(s):  
Magnesium Oxide ◽  
Plastic Flow ◽  
Lithium Fluoride ◽  
Crystal Surface ◽  
Shear Stresses ◽  
Depth Of Penetration ◽  
Diamond Crystals ◽  
Deformation And Fracture ◽  
Fluoride Crystals ◽  
The Difference

A study is made of the effect of the crystallographic direction of sliding on the friction of the (001) surfaces of diamond, magnesium oxide and lithium fluoride crystals. The friction shows marked anisotropy and with all the crystals it is greatest in the <100> directions and least in the <110> directions. The degree and magnitude of the anisotropy is dependent upon the shape of the slider and the ease with which it penetrates the crystal surface. Sharp sliders increase the degree of brittle failure and this leads to deeper penetration and to the removal of more material during sliding. With these crystals the depth of penetration is greater in the <100> directions then in the <110> and it is this which is primarily responsible for the frictional anisotropy. An explanation of frictional anisotropy is proposed which is based on the difference in the magnitude and distribution of resolved shear stresses during sliding in various crystallographic directions. This analysis is used to predict the effect of crystallographic orientation on the frictional behaviour when a (110) surface of magnesium oxide replaces the cube (001) surface used in the other experiments. Mechanisms of deformation and fracture associated with the friction are described. Brittle behaviour predominates in diamond crystals and only cleavage cracks are observed. Appreciable plastic flow occurs in both magnesium oxide and lithium fluoride crystals. With these crystals the initial plastic deformation leads to dislocation interactions which result in cracking and fracture along the {110} planes. These interact with cleavage cracks on {100} planes which are produced by tensile stress and cause surface fragmentation and wear of the crystal. Plastic flow is the only mode of deformation observed on (001) lithium fluoride surfaces when a very smooth blunt slider is used. This causes ‘pile-up’ of material along <110> directions (as previously observed in copper crystals) but it does not produce any appreciable anisotropy in the friction.

Tissue Factor-Driven Enhanced Platelet Aggregation in Flowing Blood in a Rabbit Model of Childhood Hemolytic Uremic Syndrome.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2166-2166
Author(s):  
Eric F. Grabowski ◽  
Eirini Nestoridi ◽  
Alexander Garcia ◽  
James G. Fox ◽  
Julie R. Ingelfinger
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Tissue Factor ◽  
Thrombus Formation ◽  
Rabbit Model ◽  
Renal Tissue ◽  
Shear Stresses ◽  
Normal Donor ◽  
Shear Rates ◽  
Uremic Syndrome ◽  
And Control

Abstract The Dutch belted rabbit constitutes a promising animal model of the childhood hemolytic uremic syndrome (HUS; A. Garcia, J. Infect. Dis. 2002). When Shiga toxin (Stx)-producing E. coli are administered orally, these rabbits develop HUS. Platelet-fibrin thrombus formation in this model was examined on unfixed renal tissue (5 μm sections) after mounting on 150-μm glass slides in test animal-control animal pairs. Normal donor blood, collected into 4U/ml low MW heparin and 10 μM quinacrine dihydrochoride, was drawn at shear rates of 270–650 sec-1 through a parallel-plate flow chamber for which one surface was one of the above slides. Such shear rates give rise to shear stresses which approach the 20–25 dynes/cm2 estimated to exist in glomerular arterioles. Platelets depositing on the sections were imaged in real time using epifluorescence digital videomicroscopy, with quantitation of adherent platelets via image processing. For 16 pairs of test and control sections, the percent of image pixels occupied by adherent platelets after 6–9 min of blood flow was 17.7 ± 3.06 (mean ± SD) for test sections vs 5.71 ± 5.18 for controls (P<0.001). This 3.1-fold increase for sections from Stx-treated rabbits is all the more striking considering that individual platelet aggregates on these sections were also larger and thicker, as judged from greater local pixel intensities. In 4 additional experiments, preincubation of sections with 300 nM of a monoclonal antibody (courtesy of Y. Nemerson, Mt. Sinai Medical Center, NY, NY) directed against human tissue factor (TF) with known cross-reactivity to rabbit TF markedly reduced platelet adhesion/aggregation on both test and control sections. Residual platelet deposition, which only slightly favored test sections, may be due to either a non-TF-dependent mechanism or incomplete neutralization of TF activity by the amount of antibody used. Studies of parallel fibrin deposition are in progress. Thus, renal tissue from the Dutch belted HUS model is reactive to platelets in large part via expression of TF, an expression augmented on test sections. These observations support the hypothesis that the TF pathway of coagulation plays a major role in childhood HUS.

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