Journal articles: 'Frictional forces'

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Wichelhaus, Andrea, Tena Eichenberg, Philip Gruber, Elias Panos Bamidis, and Thomas Stocker. "Friction Force Adjustment by an Innovative Covering System Applied with Superelastic NiTi Brackets and Wires—An In-Vitro Study." Materials 15, no. 12 (June 15, 2022): 4248. http://dx.doi.org/10.3390/ma15124248.

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The aim of this study was the investigation of polymeric coverings to adjust frictional forces between V-shaped wires and brackets, both made of superelastic NiTi. Adjustment of frictional forces is relevant for certain stages during orthodontic therapy. Coverings able to generate frictional forces when assembled to such brackets are additively manufactured. Six different internal widths of coverings were examined in three different environments: dry condition at room temperature (RT) or body temperature (BT), or artificial saliva (AS) at RT. The different coverings significantly affected the frictional forces for all media (p < 0.001). A correlation between internal width of the covering and resulting frictional forces was found. BT and dry environment showed the lowest friction forces for all samples. The highest force was found for two covering types at RT in AS, while the remaining four covering types showed the highest values in dry environment (p < 0.001). Friction could, therefore, be adjusted by variation of bracket covering clipped onto brackets, which is useful for orthodontic therapy. Coverings delivering higher friction provide dental anchorage, while coverings with lower friction can be used for tooth movement or purely esthetic reasons. It was shown that the variation of covering width may be used for adjustment of frictional forces.

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Bahadur, Yash Raj, Deepak Kumar Agarwal, Ankur Gupta, and P. Narayana Prasad. "Frictional Resistance in Various Ceramic Brackets using Archwires of different Alloys, Sizes and Cross sections: A Comparative Study." Orthodontic Journal of Nepal 6, no. 1 (December 12, 2016): 18–22. http://dx.doi.org/10.3126/ojn.v6i1.16174.

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Introduction: Friction at the bracket-archwire interface has been observed as one of the most important factors affecting tooth movement. Hence it is importance to assess the friction generated during tooth movement to bring about optimal treatment results.Objective: To compare the frictional resistance of various ceramic brackets using different archwires, and to compare the static and kinetic frictional force of various ceramic brackets using different archwires.Materials & Method: The present study evaluated and compared the friction generated at the bracket archwire interface when 0.018” and 0.019”x0.025” stainless steel archwires and 0.019”x0.025” teflon coated stainless steel archwires were moved through conventionally ligated, passive self-ligating and interactive self-ligating ceramic brackets. The static and kinetic frictional forces were also evaluated and compared.Result: Highly significant differences in kinetic (p<0.001) and static (p<0.001) frictional forces were observed in all three groups when used with the different archwires. On comparing the static and kinetic frictional forces significant differences were observed among all three groups (p<0.05).Conclusion: The passive self-ligating brackets produce the least frictional forces when compared to interactive self-ligating and conventionally ligated brackets. Also, the static frictional forces were found to be more as compared to kinetic frictional forces.Orthodontic Journal of Nepal, Vol. 6 No. 1, June 2016, pp.18-22

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Dragomirescu, Anca-Oana, Maria-Angelica Bencze, Adriana Vasilache, Elina Teodorescu, Cristina-Crenguța Albu, Nicoleta Olivia Popoviciu, and Ecaterina Ionescu. "Reducing Friction in Orthodontic Brackets: A Matter of Material or Type of Ligation Selection? In-Vitro Comparative Study." Materials 15, no. 7 (April 3, 2022): 2640. http://dx.doi.org/10.3390/ma15072640.

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(1) Background: Orthodontic appliances have changed and improved with the increasing demand for orthodontic treatment of the general population. Patients desire for shorter orthodontic treatments and for the wearing of more aesthetic devices has led to the technological development of orthodontic brackets; these were manufactured from aesthetic materials (ceramics, composite polymers) and presented different designs regarding the way archwires are ligated to the bracket. The aim of this study was to determine whether there were any differences between the static frictional forces generated by stainless steel (metallic) and polycrystalline alumina (ceramics) conventional and self-ligating brackets. (2) Methods: Static friction assessment was carried out in vitro with a universal testing machine, HV-500N-S (Schmidt Control Instruments, Hans Schmidt & Co. GmbH), intended for measuring compression and traction forces. (3) Results: The study revealed significant differences in static frictional forces at the bracket-archwire interface between the tested brackets. Stainless steel brackets produced lower static friction forces than polycrystalline alumina and self-ligating brackets generally produced lower static frictional forces than conventional brackets. The reduction of frictional forces was noticeable in the first stages of treatment, when thin, flexible orthodontic archwires (0.016” NiTi) are used. Engaged with large rectangular stainless steel archwires, (0.019 × 0.025” SS), the frictional forces produced by conventional and self-ligating metal brackets were similar, no significant differences being observed between the two types of metallic design. However, in the case of tested ceramic brackets, the results showed that the self-ligating type allows a reduction in frictional forces even in advanced stages of treatment compared to conventionally ligation. (4) Conclusions: From the perspective of an orthodontic system with low frictional forces, metal brackets are preferable to aesthetic ones, and self-ligating ceramic brackets are preferable to conventional ceramic brackets.

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Burstedt, Magnus K. O., Ingvars Birznieks, Benoni B. Edin, and Roland S. Johansson. "Control of Forces Applied by Individual Fingers Engaged in Restraint of an Active Object." Journal of Neurophysiology 78, no. 1 (July 1, 1997): 117–28. http://dx.doi.org/10.1152/jn.1997.78.1.117.

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Burstedt, Magnus K. O., Ingvars Birznieks, Benoni B. Edin, and Roland S. Johansson. Control of forces applied by individual fingers engaged in restraint of an active object. J. Neurophysiol. 78: 117–128, 1997. We investigated the coordination of fingertip forces in subjects who used the tips of two fingers to restrain an instrumented manipulandum with horizontally oriented grip surfaces. The grip surfaces were subjected to tangential pulling forces in the distal direction in relation to the fingers. The subjects used either the right index and middle fingers (unimanual grasp) or both index fingers (bimanual grasp) to restrain the manipulandum. To change the frictional condition at the digit-object interfaces, either both grip surfaces were covered with sandpaper or one was covered with sandpaper and the other with rayon. The forces applied normally and tangentially to the grip surfaces were measured separately at each plate along with the position of the plates. Subjects could have performed the present task successfully with many different force distributions between the digits. However, they partitioned the load in a manner that reflected the frictional condition at the local digit-object interfaces. When both digits contacted sandpaper, they typically partitioned the load symmetrically, but when one digit made contact with rayon and the other with sandpaper, the digit contacting the less slippery material (sandpaper) took up a larger part of the load. The normal forces were also influenced by the frictional condition, but they reflected the average friction at the two contact sites rather than the local friction. That is, when friction was low at one of the digit-object interfaces, only the applied normal forces increased at both digits. Thus sensory information related to the local frictional condition at the respective digit-object interfaces controlled the normal force at both digits. The normal:tangential force ratio at each digit appeared to be a controlled variable. It was adjusted independently at each digit to the minimum ratio required to prevent frictional slippage, keeping an adequate safety margin against slippage. This was accomplished by the scaling of the normal forces to the average friction and by partitioning of the load according to frictional differences between the digit-object interfaces. In conclusion, by adjusting the normal:tangential force ratios to the local frictional condition, subjects avoided excessive normal forces at the individual digit-object interfaces, and by partitioning the load according the frictional difference, subjects avoided high normal forces. Thus the local frictional condition at the separate digit-object interfaces is one factor that can strongly influence the distribution of forces across digits engaged in a manipulative act.

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Singh, Vinit, Swati Acharya, Satyabrata Patnaik, and Smruti Bhusan Nanda. "Comparative Evaluation of Frictional forces between different Archwire-bracket Combinations." Orthodontic Journal of Nepal 4, no. 1 (October 24, 2014): 22–28. http://dx.doi.org/10.3126/ojn.v4i1.11307.

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Introduction: During sliding mechanics, frictional resistance is an important counterforce to orthodontic tooth movement; whichmust be controlled to allow application of light continuous forces.Objective: To investigate static and kinetic frictional resistance between three orthodontic brackets: ceramic, self-ligating, andstainless steel, and three 0.019×0.025” archwires: stainless steel, nickel-titanium, titanium-molybdenum.Materials & Method: The in vitro study compared the effects of stainless steel, nickel-titanium, and beta-titanium archwires onfrictional forces of three orthodontic bracket systems: ceramic, self-ligating, and stainless steel brackets. All brackets had 0.022”slots, and the wires were 0.019×0.025”. Friction was evaluated in a simulated half-arch fixed appliance on a testing machine. Thestatic and kinetic friction data were analyzed with 1-way analysis of variance (ANOVA) and post-hoc Duncan multiple rangetest.Result: Self-ligating (Damon) brackets generated significantly lower static and kinetic frictional forces than stainless steel (Gemini)and ceramic brackets (Clarity). Among the archwire materials, Beta-titanium showed the maximum amount of frictional forceand stainless steel archwires had the lowest frictional force.Conclusion: The static and kinetic frictional force for stainless steel bracket was lowest in every combination of wire.

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Downing, Alison, John McCabe, and Peter Gordon. "A Study of Frictional Forces between Orthodontic Brackets and Archwires." British Journal of Orthodontics 21, no. 4 (November 1994): 349–57. http://dx.doi.org/10.1179/bjo.21.4.349.

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The differences in magnitude of static and kinetic frictional forces generated by 0·022 × 0·030-inch stainless steel (Dentaurum®) and polycrystalline ceramic (Transcend®) brackets in combinntion with archwires of different sizes (0·018 inch and 0·019 × 0·025 inch) and materials (stainless steel, nickel-titanium, and beta-titanium) at a constant ligature force were investigated. A friction-testing assembly using the Instron machine was used. In all cases, the static frictional force was greater than the kinetic frictional force. There were no significant differences in the frictional forces generated by stainless steel and polycrystalline ceramic brackets. Beta-titanium archwires produced greater frictinal forces than the other two materials. Increasing the archwire diameter increased the frictional force.

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Rozman, M. G., M. Urbakh, and J. Klafter. "Controlling chaotic frictional forces." Physical Review E 57, no. 6 (June 1, 1998): 7340–43. http://dx.doi.org/10.1103/physreve.57.7340.

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Voudouris, John C., Christos Schismenos, Kresimir Lackovic, and Mladen M. Kuftinec. "Self-Ligation Esthetic Brackets with Low Frictional Resistance." Angle Orthodontist 80, no. 1 (January 1, 2010): 188–94. http://dx.doi.org/10.2319/110608-565.1.

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Abstract Objective: To test the frictional resistance forces (FRS) generated between several archwires and (1) interactive self-ligating (ISL) brackets and (2) conventionally ligated (CL) brackets. Materials and Methods: Frictional forces produced between three different archwire combinations and self-ligating (SL) brackets (ceramic and metal-slot or all-metal) and CL brackets (metal or ceramic) were evaluated in a dry environment. The three ISL brackets tested were In-Ovation-C, In-Ovation-R, and Damon 3. The three CL brackets were Mystique with Neo Clip, Clarity, and Ovation. Each bracket was tested with 0.020″ SS, 0.019″ × 0.025″ SS and 0.018″ × 0.018″ coated SS. Results: The ISL brackets generally exhibited the lowest frictional forces irrespective of the bracket material and the wire size, and CL brackets exhibited consistently higher frictional forces. Mystique with Neo Clip produced the lowest frictional resistance of all brackets. The In-Ovation-C brackets demonstrated significantly lower frictional resistance than the SL brackets In-Ovation-R and Damon 3 as well as the CL brackets Clarity and Ovation. Conclusions: The ISL ceramic brackets produced the lowest frictional resistance of all the self-ligating brackets. The CL ceramic brackets produced the greatest friction.

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Smith, John R., Jeffrey B. Lund, and Robert K. Galloway. "Friction on PDC Cutters at High Normal Stress." Journal of Energy Resources Technology 124, no. 3 (August 6, 2002): 146–53. http://dx.doi.org/10.1115/1.1485745.

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The impact of frictional forces on the overall forces when drilling with a PDC bit has previously been implied by models and by single cutter and bit tests. This report describes new experiments to measure friction between three different bit surface materials and two different rocks over a wide range of normal stresses in up to four different fluids. Polished PDC cutters are shown to have lower frictional forces on the face of the cutter than standard cutters in both water and mineral oil. The measured friction coefficients were generally higher than reported in previous studies.

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UNGER, TAMÁS, and JÁNOS KERTÉSZ. "FRICTIONAL INDETERMINANCY OF FORCES IN HARD-DISK PACKINGS." International Journal of Modern Physics B 17, no. 29 (November 20, 2003): 5623–30. http://dx.doi.org/10.1142/s021797920302329x.

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We study the statical indeterminacy of contact forces in 2D random frictional packings of perfectly rigid disks. Based on contact dynamics simulations we perform a random walk in the force space in order to explore the equilibrium force-states for a fixed packing structure. Our measurement is in agreement with the isostaticity of frictionless hard particles, in that case forces are fully determined. For non-zero friction coefficient the problem gets undetermined, the possible force fluctuations are growing with increasing friction up to a maximum at friction coefficient around 0.1. Further increase of friction reduces the force fluctuations on the average.

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Tidy, D. C., and D. Orth. "Frictional forces in fixed appliances." American Journal of Orthodontics and Dentofacial Orthopedics 96, no. 3 (September 1989): 249–54. http://dx.doi.org/10.1016/0889-5406(89)90462-9.

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Spector, A. A., and R. C. Batra. "Rolling/Sliding of a Vibrating Elastic Body on an Elastic Substrate." Journal of Tribology 118, no. 1 (January 1, 1996): 147–52. http://dx.doi.org/10.1115/1.2837070.

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The rolling/sliding in the presence of friction of a vibrating elastic body on an elastic substrate is studied. It is shown that the longitudinal components of the velocity of the center of mass of the body and of the resultant frictional force are not affected by the vibration process. However, the normal vibration of the body influences the slip velocities and the distribution of frictional forces. For the problem of a harmonically oscillating long cylinder rolling/sliding on the flat surface of an elastic substrate, the time histories of the width of the contact zone and the length of adhesion subzone are computed. It is shown that the local frictional forces and slip velocities oscillate, and that the set of admissible values of the external frictional forces and moments providing the rolling/sliding regime is smaller under conditions of normal vibrations than that when the cylinder does not vibrate.

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Li, Qunyang, and Kyung-Suk Kim. "Micromechanics of friction: effects of nanometre-scale roughness." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2093 (February 19, 2008): 1319–43. http://dx.doi.org/10.1098/rspa.2007.0364.

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Nanometre-scale roughness on a solid surface has significant effects on friction, since intersurface forces operate predominantly within a nanometre-scale gap distance in frictional contact. To study the effects of nanometre-scale roughness, two novel atomic force microscope friction experiments were conducted, each using a gold surface sliding against a flat mica surface as the representative friction system. In one of the experiments, a pillar-shaped single nano-asperity of gold was used to measure the molecular-level frictional behaviour. The adhesive friction stress was measured to be 264 MPa and the molecular friction factor 0.0108 for a direct gold–mica contact. The nano-asperity was flattened in contact, although its hardness at this length scale is estimated to be 3.68 GPa. It was found that such a high pressure could be reached with the help of condensed water capillary forces. In the second experiment, a micrometre-scale asperity with nanometre-scale roughness exhibited a single-asperity-like response of friction. However, the apparent frictional stress, 40.5 MPa, fell well below the Hurtado–Kim model prediction of 208–245 MPa. In addition, the multiple nano-asperities were flattened during the frictional process, exhibiting load- and slip-history-dependent frictional behaviour.

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Li, Xiao Peng, Ya Min Liang, Guang Hui Zhao, Xing Ju, Hao Tian Yang, and Quan Bin Wang. "Dynamic Characteristics of Machine-Pile-Soil Vibration System with Interface Friction Coupling." Materials Science Forum 773-774 (November 2013): 632–39. http://dx.doi.org/10.4028/www.scientific.net/msf.773-774.632.

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The efficiency of vibrating machines will be greatly improved with the proper working parameters. A new type of hydraulic vibration pile driver extractor is presented in this paper. The machine-pile-soil dynamic model of the hydraulic vibration pile driver extractor based on frictional forces and vibration coupling is established with frictional forces of the pile-soil contact surface and the resistance force of the pile-end. Furthermore, the nonlinear dynamical characteristics of the dynamic model are studied and the influences of different system working parameters on frictional forces of pile-soil interface, working efficiency and capability are discussed by numerical simulation. The different working parameters are exciting force, frequency and stiffness. The results show that the suitable parameters of the vibrating machine can change the soil characteristics and decrease the frictional forces of the pile-soil interface. The work can provide useful guidance for the research on the vibration friction, selection in the suitable parameters of interface surface in engineering and design in the development of such machines.

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Sahany, Subrat Kumar, and G. Sreejith Kumar. "An In Vitro Evaluation of Frictional Characteristics of Labial and Lingual Self-ligating Brackets with Various Archwire Alloys." Journal of Indian Orthodontic Society 54, no. 3 (July 2020): 203–13. http://dx.doi.org/10.1177/0301574220921383.

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Background: An understanding of bracket slot–archwire interface is imperative for biomechanical effectiveness in orthodontic sliding mechanics and hence the aim of the study is to evaluate frictional properties of lingual self-ligating brackets comparing with conventional lingual and labial self-ligating brackets using three different archwire alloys in various environments. Materials and Methods: This in vitro study compared the frictional force of labial and lingual self-ligating and conventional lingual brackets with stainless steel, TMA, and Cr-Co alloy archwires of 0.017” × 0.025” dimension in dry and wet conditions. Frictional forces were evaluated in a simulated half arch fixed appliance using a testing machine. Static and kinetic friction were measured and analyzed by one-way analysis of variance (ANNOVA) test and post hoc Duncan multiple range test. The effects of brackets and archwires in dry and wet conditions were analyzed by three-way variance (ANNOVA) test. Result: The maximum frictional forces were observed with labial self-ligating brackets followed by lingual conventional brackets and the least by lingual self-ligating brackets. Of all the wires tested, TMA wires had the maximum frictional forces followed by Co-Cr and stainless steel. In both conditions, the values were non-significant with all bracket–wire combinations except with Co-Cr and TMA wires. Conclusions: Varied amount of frictional force was shown by the brackets and wires with highest by labial self-ligating bracket, followed by lingual conventional and lingual self-ligating brackets. TMA wires experienced higher friction followed by Co-Cr and stainless steel with minimum friction.

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Dragomirescu, Anca Oana, Elina Teodorescu, Viorica Tarmure, Andreea Baluta, Mariana Pacurar, Dorin Nenovici, Manuela Chibelean, and Ecaterina Ionescu. "Variation of Static Frictional Forces in the Fixed Orthodontic System." Revista de Chimie 70, no. 11 (December 15, 2019): 3954–56. http://dx.doi.org/10.37358/rc.19.11.7679.

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Currently, the aesthetic appearance of fixed orthodontic appliances is an important factor for patients seeking orthodontic treatment. The aim of this study was to evaluate static frictional forces generated by different types of round 0.016` NiTi archwires, with and without aesthetic coating, when coupled with monocrystalline alumina brackets. The static frictional force was determined using a testing machine for measuring compression and tension forces. The results showed a variation of static frictional forces depending on the type of archwire used. Uncoated archwires have produced the lowest static frictional forces. Partially aesthetic coated archwires have generated lower static frictional forces than fully aesthetic coated ones. Fully aesthetic coated archwires have produced the highest static frictional forces, but no significant differences were noted between archwires with polymer and epoxy resin coating.

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Dragomirescu, Anca Oana, Elina Teodorescu, Viorica Tarmure, Andreea Baluta, Mariana Pacurar, Dorin Nenovici, Manuela Chibelean, and Ecaterina Ionescu. "Variation of Static Frictional Forces in the Fixed Orthodontic System." Revista de Chimie 70, no. 11 (December 15, 2019): 3954–56. http://dx.doi.org/10.37358/rc.70.19.11.7679.

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Currently, the aesthetic appearance of fixed orthodontic appliances is an important factor for patients seeking orthodontic treatment. The aim of this study was to evaluate static frictional forces generated by different types of round 0.016 NiTi archwires, with and without aesthetic coating, when coupled with monocrystalline alumina brackets. The static frictional force was determined using a testing machine for measuring compression and tension forces. The results showed a variation of static frictional forces depending on the type of archwire used. Uncoated archwires have produced the lowest static frictional forces. Partially aesthetic coated archwires have generated lower static frictional forces than fully aesthetic coated ones. Fully aesthetic coated archwires have produced the highest static frictional forces, but no significant differences were noted between archwires with polymer and epoxy resin coating.

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Zhang, Ji Gang, Jian Han, and Wen Yan Deng. "Experimental Study of Buckling-Restrained Brace System with Pall-Typed Frictional Damper." Advanced Materials Research 163-167 (December 2010): 2973–76. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2973.

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In view of general braces of Pall-typed frictional damper will produce additional axial forces on side column in frame, considering the buckling-restrained braces(BRB) to replace the general braces to make the braces action fully, it would not generate the growth of additional axial forces on side columns, to settle basis for BRBs’ application in Pall friction damping brace system. Because hysteresis behaviors of the Pall-typed friction damper are not affected by brace buckling forces, this paper puts forward that the braces use the ordinary steel plate replacing BRB core plate to do Pall-typed frictional damping brace experimental research, meanwhile considering the geometric nonlinearity the finite element simulation analyses are done for this brace system in ANSYS software. The experimental results and simulation results show that the Pall friction force and brace forces’ variation rule is almost the same, and the brace force is almost the same.

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YU, JIAN-HONG, HENG-LI HUANG, LI-CHUN WU, JUI-TING HSU, YIN-YU CHANG, HER-HSIUNG HUANG, and MING-TZU TSAI. "FRICTION OF STAINLESS STEEL, NICKEL-TITANIUM ALLOY, AND BETA-TITANIUM ALLOY ARCHWIRES IN TWO COMMONLY USED ORTHODONTIC BRACKETS." Journal of Mechanics in Medicine and Biology 11, no. 04 (September 2011): 917–28. http://dx.doi.org/10.1142/s0219519411004149.

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In orthodontic treatment, the efficiency of tooth movement is affected by the frictional force between the archwire and bracket slot. This study evaluated the static and kinetic frictional forces produced in different combinations of orthodontic archwires and brackets. Three types of archwires [stainless steel, nickel-titanium (NiTi) alloy, and beta-titanium (TMA) alloy] and two types of brackets (stainless steel and self-ligating) were tested. Both static and kinetic frictional forces of each archwire–bracket combination were measured 25 times using a custom-designed apparatus. The surface topography and hardness of the archwires were also evaluated. All data were statistically analyzed using two-way analysis of variance and Tukey's test. The experiments indicated that the static frictional force was significantly higher than the kinetic frictional force in all archwire–bracket combinations not involving TMA wire. TMA wire had the highest friction, followed by NiTi wire, and then stainless steel wire when using the stainless steel bracket. However, there was no difference between NiTi and stainless steel archwires when using the self-ligating bracket. For TMA wire, the friction was higher when using the stainless steel bracket than when using the self-ligating bracket. Scanning electron microscopy indicated that stainless steel wire exhibited the smoothest surface topography. The hardness decreased in the order of stainless steel wire > TMA wire > NiTi wire. This study demonstrates that the frictional forces of brackets are influenced by different combinations of bracket and archwire. The reported data will be useful to orthodontists.

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Alhasan, Ahmad, Omar Smadi, Georges Bou-Saab, Nacu Hernandez, and Eric Cochran. "Pavement Friction Modeling using Texture Measurements and Pendulum Skid Tester." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 40 (May 30, 2018): 440–51. http://dx.doi.org/10.1177/0361198118774165.

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Pavement frictional behavior affects pavement performance in terms of vehicle safety, fuel consumption, and tire wear. Comprehending and interpreting pavement friction measurements is a challenging task, because of friction sensitivity to several uncontrollable factors. These factors include: pavement surface conditions, such as the type and thickness of contaminants and fluids on the surface and their interaction with friction forces; and the device operating conditions, such as sliding speed, material properties and geometry of the rubber slider used, and operating temperature. Despite the efforts to describe and quantify the impact of varying conditions on pavement friction, which ultimately will allow for a better harmonization of friction measurements, there is a need to better understand the link between the surface texture and physical friction measurements. In this paper, Persson’s friction model is used to analyze and understand the impact of surface texture on frictional behavior of dry pavement surfaces. The model was used to analyze 18 test locations, which were compared with the dry kinetic coefficients of friction (COF) estimated using a British pendulum tester (BPT). The results show that Persson’s friction model could predict the COF estimated from the BPT results with relatively high accuracy. In addition, the model could provide a profound explanation of the frictional forces mechanism. Finally, it was found that the mean profile depth (MPD) cannot provide a full picture of the frictional behavior. However, combining MPD with the Hurst exponent, texture measurements can potentially provide a full physical explanation of the frictional behavior for road surfaces.

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Mahajan, Sushil B., Sagar A. Mapare, Ram Mundada, Arjun Karra, Vijay Yannawar, and Kanchan Wadekar. "Comparison of Friction Produced at Backet-Wire Interface in Monocrystalline Ceramic Brackets of 8 Different Brands: An In Vitro Study." Journal of Pharmacy and Bioallied Sciences 16, Suppl 1 (February 2024): S356—S358. http://dx.doi.org/10.4103/jpbs.jpbs_572_23.

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ABSTRACT Introduction: The esthetic during the various orthodontic treatments has led to the invention of the brackets. When different ceramic brackets and archwires are used, the different frictional forces may result in the different outputs. Hence, in the present study, we evaluated and compared the frictional resistance between eight standard monocrystalline ceramic bracket models and each of the archwires of four different alloys. Materials and Methods: Frictional force was tested using Instron testing machine, in vitro, for eight types of monocrystalline ceramic bracket, and four types of archwires beta-titanium, NiTi, copper-nickel-titanium, and stainless steel statistical analysis were done using various tools, and significance value of <0.05 was considered. Results: Ormco and AO (Radiance) monocrystalline ceramic brackets created lesser frictional resistance than other monocrystalline ceramic brackets. Stainless steel archwire generates lesser static friction. Beta-titanium archwire created higher static friction. A 0.017 × 0.025 inch stainless steel archwire generates lesser static friction to 0.019 × 0.025 inch TMA. Conclusion: It can be concluded that Ormco and AO (Radiance) monocrystalline ceramic brackets, with stainless steel archwires and of size 0.017 × 0.025 inch, can generate better forces when used for the orthodontic tooth movements.

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Zwörner, O., H. Hölscher, U. D. Schwarz, and R. Wiesendanger. "The velocity dependence of frictional forces in point-contact friction." Applied Physics A: Materials Science & Processing 66, no. 7 (March 1, 1998): S263—S267. http://dx.doi.org/10.1007/s003390051142.

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Hanley, Kevin J., Catherine O'Sullivan, M. Ahmer Wadee, and Xin Huang. "Use of elastic stability analysis to explain the stress-dependent nature of soil strength." Royal Society Open Science 2, no. 4 (April 2015): 150038. http://dx.doi.org/10.1098/rsos.150038.

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The peak and critical state strengths of sands are linearly related to the stress level, just as the frictional resistance to sliding along an interface is related to the normal force. The analogy with frictional sliding has led to the use of a ‘friction angle’ to describe the relationship between strength and stress for soils. The term ‘friction angle’ implies that the underlying mechanism is frictional resistance at the particle contacts. However, experiments and discrete element simulations indicate that the material friction angle is not simply related to the friction angle at the particle contacts. Experiments and particle-scale simulations of model sands have also revealed the presence of strong force chains, aligned with the major principal stress. Buckling of these strong force chains has been proposed as an alternative to the frictional-sliding failure mechanism. Here, using an idealized abstraction of a strong force chain, the resistance is shown to be linearly proportional to the magnitude of the lateral forces supporting the force chain. Considering a triaxial stress state, and drawing an analogy between the lateral forces and the confining pressure in a triaxial test, a linear relationship between stress level and strength is seen to emerge from the failure-by-buckling hypothesis.

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Ke, Tao, Zhang Jun, and Tian Fang. "Dynamic Analysis and Simulation of Sliding Vane Compressor." Applied Mechanics and Materials 130-134 (October 2011): 654–57. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.654.

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The stress analysis model of sliding vane which is the critical element in a compressor is put forward and dynamic analysis of the sliding vane has been done by Mat lab in this treatise. Through analysis and computation the forces transformation ranges of sliding vane in serial production are got out and variety regularities of forces are analyzed. Based on forced analysis frictional efficiency is analyzed and imitated. The relationship of compressor’s main design parameters with frictional efficiency is searched out. The results are significant for property analysis and optimization of compressor.

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25

Giambò, Roberto, and Fabio Giannoni. "The brachistochrone problem with frictional forces." ESAIM: Control, Optimisation and Calculus of Variations 5 (2000): 187–206. http://dx.doi.org/10.1051/cocv:2000107.

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Daikhin, L. I., and M. Urbakh. "Frictional forces in an electrolytic environment." Physical Review E 59, no. 2 (February 1, 1999): 1921–31. http://dx.doi.org/10.1103/physreve.59.1921.

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Diestler, D. J., E. Rajasekaran, and X. C. Zeng. "Static Frictional Forces at Crystalline Interfaces." Journal of Physical Chemistry B 101, no. 25 (June 1997): 4992–97. http://dx.doi.org/10.1021/jp970395h.

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Wehrbein, William M. "Frictional forces on an inclined plane." American Journal of Physics 60, no. 1 (January 1992): 57–58. http://dx.doi.org/10.1119/1.17043.

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Chung, Michael, Robert J. Nikolai, Ki Beom Kim, and Donald R. Oliver. "Third-Order Torque and Self-Ligating Orthodontic Bracket–Type Effects on Sliding Friction." Angle Orthodontist 79, no. 3 (May 1, 2009): 551–57. http://dx.doi.org/10.2319/022608-114.1.

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Abstract Objective: To examine the influence of third-order torque on kinetic friction in sliding mechanics involving active and passive self-ligating brackets. Materials and Methods: Wire-slot frictional forces were quantified and compared across five sets of brackets and tubes within a simulated posterior dental segment with −15°, −10°, −5°, 0°, +5°, +10°, and +15° of torque placed in the second-premolar bracket; a working archwire was pulled through the slots. Results: Increasing the torque from 0° to ±15° produced significant increases in frictional resistance with all five sets of brackets and tubes. At 0° and ±5° of torque, generally less friction was created within the passive than within the active self-ligating bracket sets, and the conventional bracket sets with elastomeric ligation generated the most friction. At ±10° of torque, apparently with wire-slot clearance eliminated, all bracket-and-tube sets displayed similar resistances, with one exception at +10°. At ±15° of torque, one passive set and one active set produced significantly larger frictional resistances than the other three sets. Conclusions: Third-order torque in posterior dental segments can generate frictional resistance during anterior retraction with the archwire sliding through self-ligating bracket slots. With small torque angles, friction is less with passive than with active self-ligating brackets, but bracket design is a factor. Frictional forces are substantial, regardless of ligation if the wire-slot torque exceeds the third-order clearance.

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Xiong, Y. L., D. J. Sanger, and D. R. Kerr. "Geometric modelling of bounded and frictional grasps." Robotica 11, no. 2 (March 1993): 185–92. http://dx.doi.org/10.1017/s0263574700019299.

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SUMMARYThis paper, as an extension of an earlier paper, presents a geometrical representation and theoretical foundation of robot grasping that is affected by friction and by the magnitudes of normal contact forces. Grasp analysis and synthesis are based on the concepts of constraint cone (region), restraint cone and freedom cone in the force screw-space and location screw-space. In fact, the freedom cone is the aggregate of all the screws repelling and reciprocal to the grasp geometry (denoted by the restraint cone). Moreover, the constraint cone and the constraint region describe the effect of friction and the influence of the amplitudes of normal forces. The conditions of equilibrium grasp, stable grasp, form closure, force closure, and relative form closure are derived from the geometrical representation, and approaches are suggested for the design of adaptable fixtures, and for automatic grasp planning. It is shown that relative form closure is of great significance for frictional grasp, since it is possible to generate enough internal forces in the subspace spanned by the contacts and consequently produce corresponding friction forces in the reciprocal subspace.

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Berradja, Abdenacer, Guy Willems, and Jean-Pierre Celis. "Tribological behaviour of orthodontic archwires under dry and wet sliding conditions in-vitro. I - Frictional behaviour." Australasian Orthodontic Journal 22, no. 1 (May 1, 2006): 11–19. http://dx.doi.org/10.2478/aoj-2006-0002.

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Abstract Objective To evaluate the frictional behaviour of orthodontic archwires in dry and wet conditions in-vitro. Methods Two types of archwire materials were investigated: stainless steel and NiTi. A fretting wear tribometer fitted with an alumina ball was operated at 23°C in three different environments: ambient air with 50 per cent relative humidity, 0.9 wt. per cent sodium chloride solution, and deionised water. Results NiTi archwires sliding against alumina exhibited high coefficients of friction (about 0.6) in the three environments. Stainless steel archwires sliding against alumina had relatively low coefficients of friction (0.3) in the solutions, but high coefficients (0.8) in air. Conclusion The low frictional forces of the stainless steel wires sliding against alumina in the solutions were due to a lubricating effect of the solutions and corrosion-wear debris. The high frictional forces between the NiTi wires and alumina are attributed to an abrasive interfacial transfer film between the wires and alumina.

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Hsu, Hsiang Chen, and Li Ming Chu. "Nanotribology Properties and Microscopic Interfacial Frictional Behavior Studied by Atomic Force Microscopy." Advanced Materials Research 230-232 (May 2011): 639–43. http://dx.doi.org/10.4028/www.scientific.net/amr.230-232.639.

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This paper deals with the description of a method for the measurement of the nanotribology properties and microscopic interfacial frictional behavior with Atomic Force Microscopy (AFM). AFM force-displacement curve is utilized to determine the nanotribology properties. The interfacial coefficient of frictional force can be derived from a serial of calculations. A well-defined contact area is measured to study the frictional force and friction stress. The roughness of contact surface influences the contact between friction and surface forces. The study of roughness parameters corresponds to evaluate the friction and the interfacial strengths. Local variation in micro/nano tribology is also measured. The measured surface topography (3D profiles) are then applied to determinate the potential energy in molecular dynamic (MD) method to study the atomic scale frictional interactions.

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Kim, D. E., and N. P. Suh. "Molecular Dynamics Investigation of Two-Dimensional Atomic-Scale Friction." Journal of Tribology 116, no. 2 (April 1, 1994): 225–31. http://dx.doi.org/10.1115/1.2927200.

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Molecular dynamics (MD) simulation studies of two-dimensional atomic-scale frictional force are presented. The motivation for this work is to gain insight into the effects of interatomic forces on the frictional phenomena. Instantaneous friction coefficients are calculated for an atom scanning across the surface of a two-dimensional Lennard-Jones type crystal in both static and dynamic modes. It is found that net frictional force can arise even in the absence of adhesive interaction between the scanning atom and the substrate. Furthermore, in the case of nondestructive sliding the frictional interaction leads to increase in the substrate temperature which can be calculated.

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Yang, Haifeng, Kun Liu, Yanqing Wang, Hao Liu, Jiaxiang Man, and Bo Sun. "Electronic Controlling on Nanotribological Properties of a Textured Surface by Laser Processing." Journal of Spectroscopy 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/7920652.

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The friction-reducing performance of surfaces with regular nanotextures is a key topic in surface engineering research. This paper presented a simple, easily controlled method for fabricating regular nanotextures on an electrodeposited Ni-Co alloy. The electronic controlling on the friction performance of a nanotexured surface was investigated by AFM. The results showed that the frictional force of a nanotexured surface can be controlled by an external electric field. Before laser processing, the friction initially increased with the bias voltage and then decreased after the bias voltage exceeded 1.0 V. Its friction forces can be changed more than 2 times under the different external electric field. After laser processing, the trend of the frictional force was reversed and its friction forces changed more than 12 times for the laser-processed sample with 0.18 J/cm2 laser power. The results also showed that the friction force decreased when using different nanotextures in an external electric field.

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Cho, S. H., and K. A. Edge. "Adaptive sliding mode tracking control of hydraulic servosystems with unknown non-linear friction and modelling error." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 214, no. 4 (June 1, 2000): 247–57. http://dx.doi.org/10.1243/0959651001540618.

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This paper deals with the use of adaptive discrete-time sliding mode tracking control in order to assure good tracking performance as well as to guarantee robustness against non-linear frictional forces and modelling error. The control scheme ensures that the absolute value of the sliding function decreases when it is outside the sliding boundary layer and the steady state value of the sliding function is bounded by the sliding boundary layer. Application of the scheme to a hydraulic servosystem has shown that adaptively estimated frictional forces compare favourably with those obtained from direct measurement. A significant reduction in tracking error is achieved through the use of non-linear friction compensation.

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Tanbakuchi, Behrad, Sharmin Kharrazi, Matin Nikfarjam, Mohammad Sadegh Ahmad Akhoundi, and Atefe Saffar Shahroudi. "Comparative assessment of the orthodontic wire’s friction coated with zinc oxide nanoparticles by two methods of chemical precipitation and hydrothermal process." Folia Medica 64, no. 6 (December 31, 2022): 945–52. http://dx.doi.org/10.3897/folmed.64.e67842.

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Introduction: In orthodontic treatment with sliding technique, reduction of frictional forces could result in a more effective treatment. Recently, wire coating with nanoparticles were proposed to reduce frictional forces. Aim: The aim of this study was to evaluate the effect of coating wires with zinc oxide nanoparticle by two methods of chemical precipitation and direct hydrothermal process on the wire-bracket frictional force. Materials and methods: In this study, 30 pieces of stainless-steel arch wire with and without zinc oxide nanoparticles and 30 metal brackets with a 0.022-inch slot were divided into three groups: group 1 – control (uncoated wires); group 2 – wires coated with zinc oxide nanoparticles, and group 3 – wires with a thin layer of nanostructured zinc oxide. In the first method, the nanoparticles were made by chemical precipitation method, and in the second method, nanostructure was directly formed on wires. Additionally, SEM observations were used to confirm the presence of nanoparticles on the wires. Friction between wires and brackets was measured using Universal Testing Machine. SPSS v. 20 and ANOVA test was used in order to analyze the data. The significance level was considered as p<0.05. Results: The mean value of frictional forces were 1.73 N, 1.52 N, and 1.56 N in the control group, chemical precipitation method group and thin layer of nanostructured zinc oxide group, respectively. There was no significant difference in friction rate between brackets and stainless-steel wire coated by any of these two methods (p=0.555). Conclusion: Coating of orthodontic wires with zinc oxide nanoparticles can reduce friction with brackets during sliding. There was no difference in the established value of friction between coating of orthodontic wires with chemical precipitation method and thin layer coating method.

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Lakner, Thomas, and Marvin Hardt. "A Novel Experimental Test Bench to Investigate the Effects of Cutting Fluids on the Frictional Conditions in Metal Cutting." Journal of Manufacturing and Materials Processing 4, no. 2 (May 14, 2020): 45. http://dx.doi.org/10.3390/jmmp4020045.

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The tribological effect of cutting fluids in the machining processes to reduce the friction in the cutting zone is still widely unknown. Most test benches and procedures do not represent the contact conditions of machining processes adequately, especially for interrupted contacts. This results in a lack of knowledge of the tribological behavior in machining processes. To close this knowledge gap, a novel experimental test bench to investigate the effects of cutting fluids on the frictional conditions in metal cutting under high-pressure cutting fluid supply was developed and utilized within this work. The results show that there is a difference between the frictional forces in interrupted contact compared to continuous contact. Furthermore, the cutting fluid parameters of supply pressure, volumetric flow rate, and impact point of the cutting fluid jet influence the frictional forces, the intensities of which depend on the workpiece material. In conclusion, the novel test bench allows examining the frictional behavior in interrupted cuts with an unprecedented precision, which contributes to a knowledge-based design of the cutting fluid supply for cutting tools.

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Lee, W. B., C. F. Cheung, and S. To. "Friction-induced fluctuation of cutting forces in the diamond turning of aluminium single crystals." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 217, no. 5 (May 1, 2003): 615–31. http://dx.doi.org/10.1243/095440503322011344.

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This paper presents a multidisciplinary approach to the analysis of the fluctuation of cutting forces in the diamond turning of crystalline materials. The analysis is based on a microplasticity model for shear angle prediction and a cutting force model incorporating a friction variable which is estimated from the power spectrum analysis. The results reveal that the pattern of periodic fluctuation of the microcutting forces is not only due to the crystallographic orientation of the materials being cut but also to the friction between the chip and the tool face. The frictional effect is found to cause a change in the pattern and the periodicity of the fluctuation of the cutting force. The power spectrum predicted from the cutting force model incorporates a friction variable which can be chosen to match the experimental power spectrum, thus providing a new way to assess the frictional condition, and can be used as a diagnostic tool to monitor the tool wear and cutting conditions during diamond turning.

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Pattan, Sadhiq Khan, Revathi Peddu, Shyam Kumar Bandaru, Devikanth Lanka, Kalyani Mallavarapu, and Azher Banu Pathan. "Efficacy of Super Slick Elastomeric Modules in reducing Friction during Sliding: A Comparative in vitro Study." Journal of Contemporary Dental Practice 15, no. 5 (2014): 543–51. http://dx.doi.org/10.5005/jp-journals-10024-1576.

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ABSTRACT Aim To evaluate and compare the frictional resistance produced by Super Slick modules during sliding with four different types of brackets and four ligature types both in conventional and figure-of-8 ligation method with saliva as lubricant. Materials and methods The frictional resistance was evaluated by using four different ligatures on 0.019” × 0.025” stainless steel (SS) archwires using four different brackets using an universal testing machine with unstimulated saliva as a lubricant. Mean and SD values were calculated. Data was statistically analyzed using analysis of variance ANOVA with post hoc test. Results The results showed that self-ligating brackets produced least frictional forces. Among all other tested combinations, Teflon-coated SS ligatures in ceramic with metal slot brackets produced least coefficient of static and kinetic friction and full ceramic brackets ligated with Super Slick elastomeric modules demonstrated the highest, with other combinations falling in between. Conclusion Super Slick elastomeric modules, produced highest coefficient of both static and kinetic friction with the conventional and figure-of-8 ligation technique even in wet conditions using natural fresh human saliva. Clinical significance Both static and kinetic frictional resistance play an important role during sliding mechanics. Various factors have been attributed for friction. However, bracket type, archwire material, type of ligature and method of ligation are important variables. Recently polymeric coated slick elastomeric modules were introduced with the claim that they produce very low frictional forces in wet condition. Contrary to the claim made by the manufacturers of Super Slick elastomeric modules, they produced highest coefficient of both static and kinetic friction with the conventional and figure-of-8 ligation technique. How to cite this article Pattan SK, Peddu R, Bandaru SK, Lanka D, Mallavarapu K, Pathan AB. Efficacy of Super Slick Elastomeric Modules in reducing Friction during Sliding: A Comparative in vitro Study. J Contemp Dent Pract. 2014; 15(5):543-551.

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Choi, D. H., and W. Hwang. "Measurement of Frictional Forces in Atomic Force Microscopy." Solid State Phenomena 121-123 (March 2007): 851–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.851.

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A new calibration method of frictional forces in atomic force microscopy (AFM) is suggested. An angle conversion factor is defined using the relationship between torsional angle and frictional signal. When the factor is measured, the slopes of the torsional angle and the frictional signal as a function of the normal force are used to eliminate the effect of the adhesive force. Moment balance equations on the flat surface and the top edge of a commercial step grating are used to obtain the angle conversion factor. After the factor is obtained from an AFM system, it can be applied to all cantilevers without additional experiments.

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Hirano, Motohisa, Kazumasa Shinjo, Reizo Kaneko, and Yoshitada Murata. "Anisotropy of frictional forces in muscovite mica." Physical Review Letters 67, no. 19 (November 4, 1991): 2642–45. http://dx.doi.org/10.1103/physrevlett.67.2642.

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42

Pizzoni, L. "Frictional forces related to self-ligating brackets." European Journal of Orthodontics 20, no. 3 (June 1, 1998): 283–91. http://dx.doi.org/10.1093/ejo/20.3.283.

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43

Wyrembeck, Edward P. "Inductively Modeling Parallel, Normal, and Frictional Forces." Physics Teacher 43, no. 2 (February 2005): 107–10. http://dx.doi.org/10.1119/1.1855748.

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Kruyt, N. P. "Contact forces in anisotropic frictional granular materials." International Journal of Solids and Structures 40, no. 13-14 (June 2003): 3537–56. http://dx.doi.org/10.1016/s0020-7683(03)00148-3.

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45

Lannutti, John J., Andrew M. Homola, and Hung V. Nguyen. "Fluorocarbon/hydrocarbon interactions and frictional surface forces." Colloids and Surfaces A: Physicochemical and Engineering Aspects 71, no. 2 (May 1993): 155–66. http://dx.doi.org/10.1016/0927-7757(93)80340-k.

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46

Drescher, Dieter, Christoph Bourauel, and Hans-Albert Schumacher. "Frictional forces between bracket and arch wire." American Journal of Orthodontics and Dentofacial Orthopedics 96, no. 5 (November 1989): 397–404. http://dx.doi.org/10.1016/0889-5406(89)90324-7.

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Vanchikov, V. Ts. "Contact forces in frictional components of machines." Russian Engineering Research 28, no. 3 (March 2008): 209–12. http://dx.doi.org/10.3103/s1068798x08030027.

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Van Gheluwe, Bart, and Eric Deporte. "Friction Measurement in Tennis on the Field and in the Laboratory." International Journal of Sport Biomechanics 8, no. 1 (February 1992): 48–61. http://dx.doi.org/10.1123/ijsb.8.1.48.

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Tennis movements are characterized essentially by lateral displacements, thus external load on the lower extremities is created predominantly by friction generated between shoes and playing surfaces. This study analyzed the behavior of frictional forces and torques produced during an open stance forehand using various playing surfaces and different sport shoes. The frictional data were obtained from 12 advanced players returning a tennis ball fired from a ball machine and hitting a large Kistler force plate located at the base line of the tennis court. Using statistical ANOVA techniques, friction was found to be more sensitive to the choice of playing surface than to the choice of tennis shoe. “Fluid” type surfaces displayed the lowest frictional values in most cases. Additionally, comparison of the frictional data collected during the forehand with the measurements from a standardized laboratory test demonstrated that extrapolation of friction results from laboratory to real field conditions may lead to erroneous conclusions.

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Popp, Karl, Lars Panning, and Walter Sextro. "Vibration Damping by Friction Forces: Theory and Applications." Journal of Vibration and Control 9, no. 3-4 (March 2003): 419–48. http://dx.doi.org/10.1177/107754603030780.

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In this paper, we deal with the vibrational behavior of mechanical structures interconnected by contacts with friction. The focus is set on the utilization of friction forces that are generated in the contact interfaces with the objective to increase damping and to reduce vibration amplitudes in order to prevent structures from failures owing to high resonance stresses. We present a comparison and classification of different contact models that are most commonly used, including the derivation of a three-dimensional contact model under consideration of rough surfaces. We give different solution methods for problems with non-linear friction elements. The effectiveness of friction damping devices is pointed out by a single-degree-of-freedom friction oscillator, beam-like structures with frictional interfaces and different underplatform dampers in turbo-machinery applications. It can be shown that in many practical applications friction damping devices provide a remarkable decrease of vibration amplitudes.

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Chang, Chung Shin, and C. H. Chen. "Prediction of Cutting Temperatures in Milling Stainless Steels Using Sharp Worn Tools." Applied Mechanics and Materials 528 (February 2014): 191–98. http://dx.doi.org/10.4028/www.scientific.net/amm.528.191.

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The main purpose of this paper is to predict the tip's surface temperature of milling stainless steel using chamfered main cutting sharp worn tools. The cutting temperature model incorporating tool wear factor and using the variations of shear and friction plane areas occurring in tool worn situations are presented in this paper. The heat generate on elementary cutting tools are calculated by using the frictional cutting forces. Comparing the experimental forces measured by the dynamometer, that is good agreement. The carbide tip’s temperature calculates by loading the friction forces and tip’s parameters and the temperature distribution are solved by finite element analysis method.

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Journal articles on the topic 'Frictional forces'

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