Academic literature on the topic 'Anisotropic friction factor'
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Journal articles on the topic "Anisotropic friction factor"
1
Zhang, Lian Wei. "Influence of Anisotropic Internal Friction Angle on the Stability of Uniform Soil Slopes." Applied Mechanics and Materials 170-173 (May 2012): 270–73. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.270.
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The effect of anisotropy of friction angle in natural deposited soil on the stability of soil slopes was studied in this paper. Stability analysis was performed on a uniform soil slope with anisotropic friction angle. Spencer’s method was used, and the variation of friction angle was assumed to be linear to the change of direction of the slip surface. It was shown that 7-10 percent of change in safety factor might achieve within a 10m-highed anisotropic soil slope. It was also found from the analysis that that frictional anisotropy had no obvious effect on the location of critical slip surface.
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Xing, Jichun, Huajun Li, and Dechun Liu. "Anisotropic Vibration Tactile Model and Human Factor Analysis for a Piezoelectric Tactile Feedback Device." Micromachines 10, no. 7 (2019): 448. http://dx.doi.org/10.3390/mi10070448.
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Tactile feedback technology has important development prospects in interactive technology. In order to enrich the tactile sense of haptic devices under simple control, a piezoelectric haptic feedback device is proposed. The piezoelectric tactile feedback device can realize tactile changes in different excitation voltage amplitudes, different excitation frequencies, and different directions through the ciliary body structure. The principle of the anisotropic vibration of the ciliary body structure was analyzed here, and a tactile model was established. The equivalent friction coefficient under full-coverage and local-coverage of the skin of the touch beam was deduced and solved. The effect of system parameters on the friction coefficient was analyzed. The results showed that in the full-coverage, the tactile effect is mainly affected by the proportion of the same directional ciliary bodies and the excitation frequency. The larger the proportion of the same direction ciliary body is, the smaller the coefficient of friction is. The larger the excitation frequency is, the greater the coefficient of friction is. In the local-coverage, the tactile effect is mainly affected by the touch position and voltage amplitude. When changing the touch pressure, it has a certain effect on the change of touch, but it is relatively weak. The experiment on the sliding friction of a cantilever touch beam and the experiment of human factor were conducted. The experimental results of the sliding friction experiment are basically consistent with the theoretical calculations. In the human factor experiment, the effects of haptic regulation are mainly affected by voltage or structure of the ciliary bodies.
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Voytenko, I. V. "АCCOUNTING THE SEISMIC COMPONENT OF THE LATERAL PRESSURE OF AN HETEROGENEOUS ANISOTROPIC SOIL ON MASSIVE HYDROTECHNICAL STRUCTURES". Bulletin of Odessa State Academy of Civil Engineering and Architecture, № 80 (3 вересня 2020): 132–39. http://dx.doi.org/10.31650/2415-377x-2020-80-132-139.
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Abstract. Strength anisotropy is characteristic of layered soil bases and has been confirmed by numerous tests. The relevance and novelty of this research is to study the effect of the seismic factor on the active pressure of the friable soil medium having strength anisotropy. A numerical experiment was carried out using a specially developed computer program, the algorithm of which used the method for determining the lateral pressure of a heterogeneous anisotropic soil, taking into account the seismic effect. The proposed method is based on the solutions of the classical theory of Coulomb, the seismic component is taken into account on the basis of the static theory of the earthquake stability of structures. We considered a vertically ideally smooth wall in contact with a two-layer incoherent soil medium, the anisotropy of the strength properties of which is represented by hodographs of friction angle. The layers are parallel, no surface load. A numerical research was to determine the parameters of the active pressure of the soil of the lower layer during rotation of the hodograph of friction angle with steps of 300. We used 4 hodographs: 1) φ1=150-200; 2) φ2=200-250; 3) φ3=250-300; 4) φ4=300-350 with a horizontal plane of isotropy. Seismic impact was taken into account by the seismicity coefficient, taken equal to depending on the scale 0.025 (7), 0.05 (8), 0.1 (9). The horizontal orientation of the seismic force and with an angle of 200 to the horizontal plane was set. The obtained results make it possible to evaluate the seismic effect on the lateral pressure of anisotropic soil by comparing it with the corresponding indicators obtained earlier without taking into account the seismic factor. An analysis of computer solutions indicates the increase of the active pressure in seismic conditions by 14%-45% compared with the same indicator, which was determined without taking into account the seismic factor.
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Buldakova, Julia M., and Sergey G. Kudryavtsev. "Stressed state of two-layer strip when interacting with rigid base." Structural Mechanics of Engineering Constructions and Buildings 16, no. 4 (2020): 311–19. http://dx.doi.org/10.22363/1815-5235-2020-16-4-311-319.
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Relevance. In the calculation of multilayer bases, when the material of one or several layers has a pronounced anisotropy, the nature of the distribution of displacements and stresses depends on the direction of the anisotropy axes in each layer. Therefore, it is necessary to have an evaluation of the influence of this factor in the design and analysis of the operation of multilayer media. The aim of the work - to research the stress state in a strip composed of two anisotropic plane-parallel layers with different physical characteristics, lying without friction on a rigid base. Methods. The integration of the equations of the plane problem of the theory of elasticity of an anisotropic body is carried out by the symbolic method in combination with the method of initial functions. The initial functions on the contact line of the strip and the base are determined from the conditions of tight adhesion between the layers, the conditions of tight contact and the absence of friction between the strip and the base, the nature of the load applied to the upper plane of the strip. After transformations, the functions of displacements and stresses in each layer are written through the normal surface load in the form of improper integrals. Results. Plots of changes in stresses in the strip from the values of the characteristics of anisotropic materials, layer thicknesses are given. The maximum stresses on the interface line of the layers and on the line of contact with the base, depending on the direction of the anisotropy axes in each layer, are presented in the tables and shown in graphs. The effect of the elastic modules of materials on the nature of the stress distribution in a strip composed of two isotropic materials is estimated.
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Chen, Rui, Zai Hong Li, Wei Dong Lei, and Wen Bin Luo. "Strength Anisotropy of a Tailings Sand and its Effect on Stability of a Tailing Dam." Advanced Materials Research 261-263 (May 2011): 1719–23. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1719.
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In current engineering practice, the effect of strength anisotropy on stability analysis of tailings dam is often ignored. This paper presents direct shear test results on a tailing sand with different angles between shear direction and bedding plane. It is found that shear strength of this soil is significantly directional dependent. The variations in peak friction angle are about 11o, which is approximately 28.3% of the minimum value. The effect of strength anisotropy on stability of a tailings dam is also investigated. The analysis considering anisotropic strength shows a smaller factor of safety and shallower most critical slip surface as compared with isotropic strength model that is used in current engineering practice. To achieve more accurate stability analysis of tailings dams, it is suggested to take into account shear strength anisotropy of tailings soils.
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Firouzianbandpey, S., D. V. Griffiths, L. B. Ibsen, and L. V. Andersen. "Spatial correlation length of normalized cone data in sand: case study in the north of Denmark." Canadian Geotechnical Journal 51, no. 8 (2014): 844–57. http://dx.doi.org/10.1139/cgj-2013-0294.
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The main topic of this study is to assess the anisotropic spatial correlation lengths of a sand layer deposit based on cone penetration testing with pore pressure measurement (CPTu) data. Spatial correlation length can be an important factor in reliability analysis of geotechnical systems, yet it is rarely estimated during routine site investigations. Results from two different sites in the north of Denmark are reported in this paper, indicating quite strong anisotropy due to the depositional process, with significantly shorter spatial correlation lengths in the vertical direction. It is observed that the normalized cone resistance is a better estimator of spatial trends than the normalized friction ratio.
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Alexandrov, Sergei, Elena Lyamina, Hguyen Minh Tuan, and Natalia Kalenova. "Effect of Plastic Anisotropy on the Strain Rate Intensity Factor: A Simple Analytic Solution." Key Engineering Materials 626 (August 2014): 240–45. http://dx.doi.org/10.4028/www.scientific.net/kem.626.240.
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Solutions for many rigid/plastic models are singular in the vicinity of maximum friction surfaces. In particular, the magnitude of the equivalent strain rate near such surfaces is controlled by the strain rate intensity factor. This factor is the coefficient of the leading singular term is a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. Since the equivalent strain rate has a great effect of material properties, it is of important to reveal the dependence of the strain rate intensity factor on parameters characterizing material models. In the present paper, quite a general model of anisotropic plasticity under plane strain conditions is adopted. Then, using an analytic solution for instantaneous compression of a layer of plastic material between two parallel plates the effect of the shape of the yield locus on the asymptotic behavior of the equivalent strain rate in the vicinity of the friction surface is demonstrated.
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Yang, An-Shik, and Ching-Chang Chieng. "Turbulent Heat and Momentum Transports in an Infinite Rod Array." Journal of Heat Transfer 109, no. 3 (1987): 599–605. http://dx.doi.org/10.1115/1.3248130.
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An anisotropic factor is carefully selected from eleven distributions and adopted to the k–ε two-equation model of turbulence to obtain detailed velocity and temperature fields for steady-state, fully developed turbulent flow through infinite triangular/square rod array. The present study covers the ranges of pitch-to-diameter ratio from 1.123 to 1.5, and Reynolds number from 2.4 × 104 to 106. Velocity and wall shear stress are calculated and compared to experimental data. Normalized fluid temperature, friction factor, and heat transfer coefficient are also computed. The correlations of friction factor and heat transfer coefficients for flow inside circular pipe and flow through finite rod arrays are compared with the results for flow through infinite rod arrays.
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Naimil, E. K., S. S. Bazalevskaya, O. M. Kugaenko, and V. S. Petrakov. "Study of acoustic parameters of lanthanum-gallium tantalate single crystals subjected to cyclic deformation and thermal shock." Industrial laboratory. Diagnostics of materials 84, no. 11 (2018): 28–35. http://dx.doi.org/10.26896/1028-6861-2018-84-11-28-35.
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The effect of crystal anisotropy and defects of the structure formed upon mechanical cyclic deformation and thermal shock on acoustic parameters such as phase velocity, attenuation coefficient, Q-factor of bulk acoustic wave (BAW) has been studied in lanthanum-gallium tantalate (LGT, La3Ta0,5Ga5,5O14) anisotropic piezoelectric single crystals using inner friction (IF) method with multiple piezoelectric vibrator at a frequency of 105 Hz. The anisotropy of the effective elasticity modulus (E), BAW phase velocity (Vp), attenuation coefficient and Q-factor was observed in anisotropic LGT single crystals. It is shown that cyclic deformation of LGT samples under a load of 2.5 kN with the number of load cycles up to 5 x 105 with a cycling frequency of 100 MHz and thermal shock (100 - 120°C) have no effect on the values of the effective elasticity modulus and phase velocity of the longitudinal BAW, respectively: for X-cut — E =111 GPa, Vp = 4250 m/sec; for Z-cut — E = 181 GPa, Vp = 5430 m/sec. The attenuation coefficient of the longitudinal BAW increased by 1.5 - 2 times after cyclic deformation for both X-and Z-cuts, which resulted in a two-fold decrease of the quality factor. Thermal shock has almost no effect on the attenuation coefficient and Q-factor for X-cut samples. For Z-cut samples thermal shock leads to a three-fold increase of the attenuation coefficient and decrease of the Q-factor. Sensitive elements of piezopressure sensors based on langatate should be protected from thermal shock at a temperature above 150°C, and the total number of the mechanical compression cycles of the material should not exceed 5 x 105 cycles at a frequency of 100 - 150 Hz with the loads not exceeding 2.5 kN.
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Shi, Yuling, Rui Wang, Hang Yuan, Han Bao, and Changgen Yan. "Quantitative Reinforcement Analysis of Loess Slope with Anisotropy." Advances in Civil Engineering 2019 (May 15, 2019): 1–12. http://dx.doi.org/10.1155/2019/6728101.
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The loess slope in east Gansu presents a large degree of anisotropy which should be considered both in the slope stability analysis and in the reinforcement design. To investigate the mechanical anisotropy presented in the loess soil, the undisturbed loess specimens are taken from the field with different sampling directions (α, defined as the angle between the normal direction of specimen and sedimentation direction). The direct shear tests are conducted on specimens of different α, and it is found that the anisotropy has slight influence on the friction angle (φ), while the specimen with α=0° presents the smallest cohesion and the specimen with α=90° has the largest cohesion. The anisotropy behaviors have also been observed from the one-dimensional consolidation test and tension test. After that, the principle of point safety factor and the degree of reinforcement demand are introduced, and the method of quantitative reinforcement of anisotropic loess slope is proposed. The proposed approach is then implemented in the Fast Lagrangian Analysis of Continua in 3D (FLAC3D), and the point safety factor and the degree of reinforcement demand are investigated on slope with different slope ratios. It is found that the proposed approach could effectively be used to analyze the slope involving anisotropy through the comparison with the conventional limit equilibrium method. Meanwhile, the reinforcement zone and the reinforcement demanding of anisotropy slope are obtained, and relevant reinforcement design in practice is proposed.
Dissertations / Theses on the topic "Anisotropic friction factor"
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Cha, Jeesung Jeff. "Hydrodynamic Parameters of Micro Porous Media for Steady and Oscillatory Flow: Application to Cryocooler Regenerators." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-07092007-194225/.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2008.<br>Jeremy P. Harvey, Committee Member ; Carl S. Kirkconnell, Committee Member ; Kurt D. Pennell, Committee Member ; S. Mostafa Ghiaasiaan, Committee Chair ; Prateen V. Desai, Committee Member ; Sheldon M. Jeter, Committee Member.
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Landrum, Evan. "Anisotropic parameters of mesh fillers relevant to miniature cryocoolers." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28159.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Ghiaasiaan, S. Mostafa; Committee Member: Desai, Prateen; Committee Member: Jeter, Sheldon; Committee Member: Kirkconnell, Carl.
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Hossain, M. Jayed. "Factors influencing cartilage wear in an accelerated in vitro test: collagen fiber orientation, anatomic location, cartilage composition, and photo-chemical crosslinking." Thesis, 2018. https://doi.org/10.7912/C29W87.
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Indiana University-Purdue University Indianapolis (IUPUI)<br>Articular cartilage (AC) is a strong but flexible connective tissue that covers and
protects the end of the long bones. Although cartilage has excellent friction and wear
properties that allow smooth joint function during daily activities, these properties
are not fully understood. Many material properties of cartilage are anisotropic and
vary with anatomic location and the composition of the tissue, but whether this is
also true for cartilage friction and wear has not been previously determined. Furthermore, cartilage disease and injury are major health concerns that affect millions of
people, but there are few available treatments to prevent the progression of cartilage
degeneration. Collagen crosslinking may be a potential treatment to reduce cartilage
wear and slow or prevent the progression of cartilage disease. The objectives of this
thesis were to investigate the relationships between the friction/wear characteristics of
cartilage and the orientation of the preferred fiber direction, the anatomic location of
the tissue, the composition of the tissue, and exogenous photochemical crosslinking.
In the superficial zone, AC has preferential fiber direction which leads to anisotropic
material behavior. Therefore, we hypothesized that AC will show anisotropic behavior between longitudinal and transverse direction in an accelerated, in vitro wear test
on bovine cartilage in terms of friction and wear. This hypothesis was proven by the
quantification of glycosaminoglycans released from the tissue during the wear test,
which showed that more glycosaminoglycans were released when the wear direction
was transverse to the direction of the fibers. However, the hydroxyproline released
from the tissue during the wear test was not significantly different between the two
directions, nor was the coefficient of friction.
The material properties of AC can also vary with anatomic location, perhaps due
to differences in how the tissue is loaded in vivo. We hypothesized that cartilage
from a higher load bearing site will give better wear resistance than cartilage from
lower load bearing regions. However, no differences in friction or wear were observed
between the different anatomic locations on the bovine femoral condyles. The concentration of collagen, glycosaminoglycans, cells and water in the tissue was also
quantified, but no significant differences in tissue composition were found among the
locations that were tested.
Although wear did not vary with anatomic location, variation in the wear measurements were relatively high. One potential source of variation is the composition
of the cartilage. To determine whether cartilage composition influences friction and
wear, a correlation analysis was conducted. An accelerated, in vitro wear test was
conducted on cartilage from bovine femoral condyles, and the tissue adjacent to the
wear test specimens was analyzed for collagen, glycosaminoglycan, cell, and water
content. Because wear occurs on the cartilage surface, the superficial zone of the
cartilage might play an important role in wear test. Therefore, composition of the
adjacent cartilage was determined in both the superficial zone and the full thickness
of the tissue. A significant negative correlation was found between wear and collagen
content in the full thickness of the tissue, and between the initial coefficient of friction
and the collagen content in the superficial zone. This correlation suggests that variation in the collagen content in the full thickness of the cartilage partially explains
differences in amount of wear between specimens.
The wear resistance of cartilage can be improved with exogenous crosslinking
agents, but the use of photochemical crosslinking to improve wear resistance is not well
understood. Two photochemical crosslinking protocols were analyzed to improve the
wear resistance of the cartilage by using chloro-aluminum phthalocyanine tetrasulfonic
acid (CASPc) and 670nm laser light. The cartilage treated with the two crosslinking
protocols had lower wear than the non-treated group without changing the friction
properties of the cartilage.
Book chapters on the topic "Anisotropic friction factor"
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Li, Qiang. "Anisotropic Mechanical Properties of 2-D Materials." In Plastic Deformation in Materials [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96598.
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While prior reviews and research articles focused on the various synthetic routes and microstructural controls of 2D nanomaterials as well as their functional applications, this chapter discloses the anisotropic behaviors of 2D materials and puts emphasis on the mechanical anisotropy of three distinct 2D materials, namely graphene, MoS2 and Al alloy coating, representative of carbon, inorganic and metallic 2D crystalline materials. Except for the relatively low interlayer cohesive stress, the in-plane anisotropy of the former two materials classes is subjected primarily to the hexagonal structure of the unit cells of the graphene and MoS2. The anisotropy of metallic thin films with high-density grain boundaries with preferential directionality, rendered by the non-equilibrium synthetic methods, results from both the conventional Taylor factor and the directionality of the grain boundaries. Despite 2D materials’ wide spectrum of applications, such as electronics, energy devices, sensors, coating etc., the mechanical anisotropy could be critical for certain mechanical applications, such as friction, and provide instructions on the durability, reliability and property optimization in the various applications of different 2D materials.
Conference papers on the topic "Anisotropic friction factor"
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Alexandrov, Sergei. "An Effect of Plastic Anisotropy on the Strain Rate Intensity Factor." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24021.
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The strain rate intensity factor in the theory of rigid perfectly plastic isotropic materials is the coefficient of the principal singular term in a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. This coefficient can be used to predict the evolution of material properties in a narrow layer in the vicinity of surfaces where the friction stress is high. Usually, conventional evolution equations are not compatible with the plasticity equations near maximum friction surfaces. It is therefore of interest to extend the theories based on the strain rate intensity factor to more general models than the rigid perfectly plastic isotropic solids. The present paper deals with plane strain deformation of rigid plastic anisotropic material. It is shown by means of a simple analytic solution that the velocity field is singular in the vicinity of maximum friction surfaces. Thus the strain rate intensity factor can be introduced for such materials. An effect of plastic anisotropy on its value is demonstrated. In addition, it is shown that rigid plastic solutions for anisotropic materials can exhibit various types of singularity in the vicinity of maximum friction surfaces, in contrast to isotropic materials where one type only is possible. Nevertheless, in most cases the type of singularity is same for isotropic and anisotropic materials.
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Mouassa, Ahcene, Mustapha Lahmar, and Benyebka Bou-Said. "A Study of Combined Effects of Surface Roughness and Lubricant Rheology on the Hydrodynamic Contact Behavior Using the Homogenized Method." In STLE/ASME 2010 International Joint Tribology Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ijtc2010-41025.
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The combined effects of surface roughness and lubricant rheology on the performance characteristics of a hydrodynamic inclined slider bearing are investigated by means of the homogenized method. The pad surface is rough and stationary while the lower surface is assumed to be smooth and moving. The V. K. Stokes couple stress fluid model is adopted to describe the rheological behavior of the lubricant flowing between the two surfaces. The numerical simulations are performed by considering three roughness patterns (transverse, longitudinal and anisotropic), and various values of the couple stress parameter. It is found that the homogenization method is rigorous and efficient for the three roughness patterns considered. It is also found that the combined effects of the surface roughness as well as the couple stress due to the presence of polymer additives on the hydrodynamic performance characteristics such as load carrying capacity, friction factor are significant.
3
Jocsak, Jeffrey, Yong Li, Tian Tian, and Victor W. Wong. "Analyzing the Effects of Three-Dimensional Cylinder Liner Surface Texture on Ring-Pack Performance With a Focus on Honing Groove Cross-Hatch Angle." In ASME 2005 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/icef2005-1333.
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Frictional losses in the piston ring-pack of an engine account for approximately 20% of the total frictional losses within an engine. Although many non-conventional cylinder liner finishes are now being developed to reduce friction and oil consumption, the effects of the surface finish on ring-pack performance is not well understood. The current study focuses on modeling the effects of three-dimensional cylinder liner surface anisotropy on piston ring-pack performance. A rough surface flow simulation program was developed to generate flow factors and shear stress factors for three-dimensional cylinder liner surface textures. Rough surface contact between the ring and liner was modeled using a previously published methodology for asperity contact pressure estimation between actual rough surfaces. The surface specific flow factors, shear stress factors, and asperity contact model were used in conjunction with MIT’s previously developed ring-pack simulation program to predict the effects of different surface textures on ring-pack behavior. Specific attention was given to the effect of honing groove cross-hatch angle on piston ring-pack friction in a stationary natural gas engine application, and adverse effects on engine oil consumption and durability were also briefly considered. The modeling results suggest that ring-pack friction reduction is possible if the liner honing cross hatch angle is decreased by reducing the feed-to-speed ratio of the honing tool. Reducing the cross-hatch angle increased oil flow blockage and increased the lubricant’s effective viscosity during mixed lubrication. This allowed more load to be supported by hydrodynamic pressure, reducing ring-pack friction. However, there appeared to be a potential for increased oil consumption and scuffing tendency corresponding to a decrease in honing cross-hatch angle.
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Roppenecker, Daniel B., Rebecca Grazek, Johannes A. Coy, Franz Irlinger, and Tim C. Lueth. "Friction Coefficients and Surface Properties for Laser Sintered Parts." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64549.
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Today different types of established rapid prototyping (RP) systems are available. In a Selective Laser Sintering (SLS)-process a CAD-model is designed and converted into a STL-file (Standard Tessellation Language). Next the body information is sliced into layers and transferred to the production system. By melting the powder-material using a laser beam, parts can be created layer by layer. Afterwards the parts are cleaned and several finishing treatments can be applied. The primarily aim in using RP was to reduce the product development time and to create design models. Nowadays whole assemblies and complex parts can be produced altogether in one manufacturing step with RP-systems. To ensure a save part construction due to calculation formulas and basic material constants, predictable design calculations are necessary. Concerning SLS-materials like polyamide PA 2200 components, only specific mechanical values like the tensile and flexural modulus have been identified. To fill this gap concerning tribological characteristics and to reach the next level of rapid manufacturing the key aspects of this article are the determination of the coefficient of friction μ0 of SLS-parts made of polyamide PA 2200 concerning several influence factors. An anisotropic material behavior, a decrease of the coefficient of friction μ0 with increasing contact pressure, larger contact areas and more intensive finishing treatment could be detected. Due to the knowledge of the identified material properties, now friction loaded components can be configured and used as functional machine parts.
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Crowley, Ross, and Joseph Domblesky. "Analysis of Anisotropic Surface Topography Effects on Metal Flow: Warm and Hot Working Processes." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8304.
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Abstract The results of an experimental study that analyzed how anisotropic tool topography influences friction and metal flow under warm and hot working conditions are presented. Six sets of H-13 steel platens having different roughnesses were used to compress AA 6061-T6, AA 2024-T4, and AISI 1018 specimens. The platens were machined to have a unidirectional lay while the specimens were prepared to have a constant roughness with an isotropic surface texture. Rectangular specimens were placed at different angular orientations relative to the surface lay of the graphite-lubricated platens and then side-pressed at die temperatures ranging from 149–204°C (300–400°F). Ring tests were also performed in order to determine interface shear friction factors for each experimental condition. Results showed that surface roughness had little effect on planar metal flow whereas specimen orientation showed a strong correlation. An explanation for this behavior is presented based on evidence gathered with a laser measuring microscope. While further investigation is needed, the results indicate that an oriented surface texture has the potential to be used as a tool to optimize flow patterns in bulk forming processes.
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Tikhonov, Vadim, Khaydar Valiullin, and Lev Ring. "Numerical Simulation of Well Trajectory While Drilling Isotropic and Anisotropic Formations." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82080.
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In spite of research efforts to develop a numerical model for predicting wellbore trajectory, there isn’t an adequate model for simulating new hole creation and predicting wellbore curvature and build rates that accounts for bottomhole assembly (BHA) dynamics, geometric constraints, rock properties, and steering tool action. This paper presents new, comprehensive 3D model of BHA dynamics for lateral and torsional modes of motion. This model includes the presence of stabilizers and sections with different geometric and mechanical properties along the BHA. It considers changes in trajectory due to action of bent subs or rotary steerable systems (RSS); allows for abrupt changes to friction factors during transitions from sliding to rolling motions in the wellbore; and accounts for the effects of the bit’s side-milling capacity and side load changes due to changes in the formation. The DYNTUB software, an advanced simulation tool for predicting well trajectories while drilling, was developed based on this model. This paper presents a mathematical model for the BHA and the well trajectory, the numerical integration method, and the results calculated for various examples steering tools and formations.
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Kaiho, Yuichi, Shumpei Hara, Takahiro Tsukahara, and Yasuo Kawaguchi. "Spectral Analysis and Discussion on the Velocity Fluctuation in Drag Reducing Channel Flow by Surfactant Additives." In ASME 2016 Fluids Engineering Division Summer Meeting collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fedsm2016-7725.
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It is known as the Toms effect that the wall friction coefficient is reduced by adding a small amount of polymer or surfactant into a water flow. In the drag-reducing flow, it is expected that a time scale of turbulent velocity fluctuation is changed by relaxation time due to viscoelasticity. In the present study, experimental analysis of the turbulent velocity fluctuation was performed with temporal characteristics in surfactant solution flow. The velocity fluctuations were measured by using a two-component laser Doppler velocimeter system on turbulent channel flow. And then, we performed statistical operation on those data and examined the time scale. From spectra analysis, it was found that very low frequency velocity fluctuations existed near the wall region in the surfactant solution flow. It was also revealed that the strong anisotropy occurred not only with the intensity but also with frequency distribution in turbulent velocity fluctuations. Moreover, the turbulence contributes nothing to the Reynolds shear stress and behaves as a wave motion. It was concluded that the turbulent eddies and viscoelasticity were two factors contributing to turbulent generation in the viscoelastic turbulent flow, with each factor having its own time scale.
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Lorenz, M., A. Schulz, and H. J. Bauer. "Predicting Rough Wall Heat Transfer and Skin Friction in Transitional Boundary Layers: A New Correlation for Bypass Transition Onset." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68910.
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This paper summarizes the experimental results of a comprehensive study on heat transfer and aerodynamic losses of a highly loaded turbine blade with surface roughness. A few hundred test cases conducted at several Reynolds numbers, freestream turbulence levels, and different deterministic roughness geometry have been examined. Some of these results have been published in two former papers showing a strong effect of roughness on laminar-turbulent bypass transition on the airfoil suction side. Beside roughness height, roughness anisotropy has turned out to be one of the major influencing factors. The airfoil heat transfer distribution of these measurements is used for detecting transition onset. Additionally, further transition onset data from literature is reevaluated. Thus, important roughness (geometry) parameters are identified and a new correlation for transition onset is deduced including roughness parameters as well as freestream turbulence. Moreover, a method to extract the relevant roughness parameters from real surface roughness is presented. Additional heat transfer and aerodynamic measurements are conducted for two different real surface roughness types. Calculations with a 2D-boundary layer code on these surfaces are presented in order to validate the new model.
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Kriventsev, Vladimir, Hiroyuki Ohshima, Akira Yamaguchi, and Hisashi Ninokata. "Numerical Prediction of Secondary Flows in Complex Areas Using Concept of Local Turbulent Reynolds Number." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22333.
Full textAbstract:
A new model of turbulence is proposed for the estimation of Reynolds stresses in turbulent fully-developed flow in a wall-bounded straight channel of an arbitrary shape. Ensemble-averaged Navier-Stokes, or Reynolds, equations are considered to be sufficient and practical enough to describe the turbulent flow in complex geometry of rod bundle array. We suggest the turbulence is a process of developing of external perturbations due to wall roughness, inlet conditions and other factors. We also assume that real flows are always affected by perturbations of any possible scale lower than the size of the channel. Thus, turbulence can be modeled in the form of internal or “turbulent” viscosity. The main idea of a Multi-Scale Viscosity (MSV) model can be expressed in the following phenomenological rule: A local deformation of axial velocity can generate the turbulence with the intensity that keeps the value of the local turbulent Reynolds number below some critical one. Therefore, in MSV, the only empirical parameter is the critical Reynolds number. From analysis of dimensions, some physical explanations of Reynolds number are possible. We can define the local turbulent Reynolds number in two ways: i) simply as Re = ul/v, where u is a local velocity deformation within the local scale l and v is total accumulated molecular and turbulent viscosity of all scales lower then 1. ii) Re = K/W, where K is kinetic energy and W is work of friction/dissipation forces. Both definitions above have been implemented in the calculation of samples of basic fully-developed turbulent flows in straight channels such as a circular tube and annular channel. MSV has been also applied to prediction of turbulence-driven secondary flow in elementary cell of the infinitive hexagonal rod array. It is known that the nature of these turbulence-driven motions is originated in anisotropy of turbulence structure. Due to the lack of experimental data up to date, numerical analysis seems to be the only way to estimate intensity of the secondary flows in hexagonal fuel assemblies of fast breeder reactors (FBR). Since MSV can naturally predict turbulent viscosity anisotropy in directions normal and parallel to the wall, it is capable to calculate secondary flows in the cross-section of the rod bundle. Calculations have shown that maximal intensity of secondary flow is about 1% of the mean axial velocity for the low-Re flows (Re = 8170), while for higher Reynolds number (Re = 160,100) the intensity of secondary flow is as negligible as 0.2%.