Journal articles: 'Sensitivity to the friction coefficient'

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Yevtushenko, Aleksander A., Piotr Grzes, and Adam Adamowicz. "The Temperature Mode of the Carbon-Carbon Multi-Disc Brake in the View of the Interrelations of Its Operating Characteristics." Materials 13, no. 8 (April 16, 2020): 1878. http://dx.doi.org/10.3390/ma13081878.

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In this paper, a methodology for conducting a computer simulation of the frictional heating process of a multi-disc braking system is proposed. The single braking of a system of three identical discs made of carbon–carbon (C/C) carbon frictional composite material (CFCM) is considered. In order to determine the operational characteristics of the brake, a heat dynamics of friction (HDF) system of equations is formulated, which takes into account the contact pressure rise time, thermal sensitivity of the C/C material, the change in the coefficient of friction during braking, the parameters of the friction surface’s microgeometry and the mutual influence of sliding velocity and temperature. A numerical solution using the finite element method (FEM) of the HDF system of equations allows us to determine changes in key braking process characteristics, such as work done, braking torque, friction coefficient, heat transfer coefficient, velocity and temperature. Finally, a comparative analysis of the results obtained for three different time profiles of the coefficient of friction is carried out.

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Qiu, Xiaoli, Xianqiang Cheng, Penghao Dong, Huachen Peng, Yan Xing, and Xin Zhou. "Sensitivity Analysis of Johnson-Cook Material Constants and Friction Coefficient Influence on Finite Element Simulation of Turning Inconel 718." Materials 12, no. 19 (September 25, 2019): 3121. http://dx.doi.org/10.3390/ma12193121.

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The Johnson-Cook (J-C) constitutive model, including five material constants (A, B, n, C, m), and the Coulomb friction coefficient (μ) are critical preprocessed data in machining simulations. Before they become reliable preprocessed data, investigating these parameters’ effect on simulation results benefits parameter-selecting. This paper aims to investigate the different influence of five settings of the J-C constitutive equation and Coulomb friction coefficient on the turning simulation results of Inconel 718 under low-high cutting conditions, including residual stress, chip morphology, cutting force and temperature. A three-dimensional (3-D) finite element model was built, meanwhile, the reliability of the model was verified by comparing the experiment with the simulation. Sensitivity analysis of J-C parameters and friction coefficient on simulation results at low-high cutting conditions was carried out by the hybrid orthogonal test. The results demonstrate that the simulation accuracy of Inconel 718 is more susceptible to strain hardening and thermal softening in the J-C constitutive model. The friction coefficient only has significant effects on axial and radial forces in the high cutting condition. The influences of the coefficient A, n, and m on the residual stress, chip thickness, cutting force and temperature are especially significant. As the cutting parameters increase, the effect of the three coefficients will change visibly. This paper provides direction for controlling simulation results through the adjustment of the J-C constitutive model of Inconel 718 and the friction coefficient.

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Sharifi Miavaghi, Amir, Haleh Kangarlou, and Mehdi Eskandarzade. "Comparison between frictional behavior of the soft and brittle materials at different contact pressures." Lebanese Science Journal 18, no. 1 (June 21, 2017): 98–105. http://dx.doi.org/10.22453/lsj-018.1.098105.

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Coefficient of friction changed significantly by the change in contact pressure. Experimental measurement of the coefficient of friction in different contact pressures can be useful in numerical and analytical analysis of many engineering problems, such as metal forming process. This study dedicated to investigate the sensitivity of the friction coefficient to changes in contact pressures. To aim this goal the special tribometer device has been fabricated and the coefficient of friction of the soft and brittle metals when sliding with a low speed on a rigid body are measured for different contact pressures. The friction sensitivity of the soft (copper and aluminum) and brittle (steel) samples to changes in contact pressure are compared and discussed. The results showed that both brittle and soft metals are highly sensitive for change in contact pressure but their behaviour is slightly different. While the coefficient of friction of the steel sample when sliding on a steel substrate is reduced sharply by a little increase in contact pressure; the coefficient of friction of the soft material when sliding on a steel substrate is reduced slowly depending on the magnetude of the applied normal load.

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BOAZU, Doina. "A Sensitivity Study of the Maximum Stress in a Rubber Circular Ring to the Coefficient of Friction Using FEM." Annals of “Dunarea de Jos” University of Galati. Fascicle IX, Metallurgy and Materials Science 45, no. 4 (December 15, 2022): 29–35. http://dx.doi.org/10.35219/mms.2022.4.05.

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The paper presents a sensitivity study of a rubber circular ring (O-Ring) depending on the value of the coefficient of friction (design parameter) between the ring and the surfaces between which it is mounted. The response value is the maximum von Mises stress in the rubber ring. The influence of temperature was not taken into account.Through this sensitivity nonlinear analysis using finite element modeling, the correlation between Equivalent maximum Von Mises Stress and Friction coefficient can be established, determining a maximum stress level of the rubber ring to the friction coefficient. This relationship is important for the preload stage of the gasket functioning.

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Wang, Qiang, Youmin Tang, and Henk A. Dijkstra. "An Optimization Strategy for Identifying Parameter Sensitivity in Atmospheric and Oceanic Models." Monthly Weather Review 145, no. 8 (August 2017): 3293–305. http://dx.doi.org/10.1175/mwr-d-16-0393.1.

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A new optimization strategy is proposed to identify the sensitivities of simulations of atmospheric and oceanic models to uncertain parameters. The strategy is based on a nonlinear optimization method that is able to estimate the maximum values of specific parameter sensitivity measures; meanwhile, it takes into account interactions among uncertain parameters. It is tested using the Lorenz’63 model and an intermediate complexity 2.5-layer shallow-water model of the North Pacific Ocean. For the Lorenz’63 model, it is shown that the parameter sensitivities of the model results depend on the initial conditions. For the 2.5-layer shallow-water model used to simulate the Kuroshio large meander (KLM) south of Japan, the optimization strategy reveals that the prediction of the KLM path is insensitive to the uncertainties in the bottom friction coefficient, the interfacial friction coefficient, and the lateral friction coefficient. Rather, the KLM prediction is relatively sensitive to the uncertainties of the reduced gravity representing ocean stratification and the wind stress coefficient.

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Espinosa, H. D., A. J. Patanella, and M. Fischer. "Dynamic Friction Measurements at Sliding Velocities Representative of High-Speed Machining Processes." Journal of Tribology 122, no. 4 (April 17, 2000): 834–48. http://dx.doi.org/10.1115/1.1310331.

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Understanding high speed machining processes requires knowledge of the dynamic friction response at the tool-workpiece interface, the high strain rate response of the workpiece material and its fracture mechanisms. In this paper, a novel experimental technique, consisting in the independent application of an axial static load and a dynamic torque, is used to investigate time resolved dynamic friction. Shear stress wave propagation along an input bar, pressing statically against an output bar, is analyzed. The quasi-static and kinetic friction coefficients of Ti-6Al-4V sliding against 1080 Steel, Al 6061-T6 sliding against 1080 Steel, and Al 6061-T6 sliding against Al 7075-T6, with various surface characteristics, are investigated. Sliding velocities up to 6.9 m/s are achieved. Surface roughness is varied to understand its role on the frictional response of the sliding interfaces. The dependence of friction coefficient on material strain-rate sensitivity is also assessed. Measured friction coefficients compared well with values reported in the literature using other experimental techniques. The experimental methodology discussed in this article provides a robust method for direct measurement of the quasi-static and dynamic friction coefficients representative of high-speed machining, metal-forming and ballistic penetration processes. [S0742-4787(00)01304-7]

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Bahrami Balfeh Teimouri, Atanaz, and Ahad Bagherzadeh Khalkhali. "Stability Control of Narmab Dam and Sensitivity Analysis of Reliability Coefficients." Civil Engineering Journal 4, no. 9 (September 30, 2018): 2197. http://dx.doi.org/10.28991/cej-03091150.

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Static and quasi-static stability analysis of embankment dams is of vital importance in different stages of dam’s design, construction and operation. The stability can be studied using different techniques which are generally analyzed through Limit Equilibrium Method. Base on this main method, the critical slip surface is selected and the shear strength required to counter the slip at the selected surface is obtained and compared with shear strength of the soil at that surface in order to obtain confidence coefficient. In the present research, the Geo-studio Slope/w software that is a geotechnical software based on finite element method and is widely used in geotechnical field, is employed in order to analyze the stability of the body and foundation of Narmab dam in Golestan province. Narmab dam is a homogeneous embankment dam with a height of 60 m, crest length of 807 m and reservoir volume of 115 million cubic meters. The confidence coefficients provided by the software are compared to the permissible confidence coefficients. Moreover, the sensitivity of the confidence coefficients values to the changes in the effective factors, adhesion and internal friction coefficient, is analyzed. The analyses were performed on 8 values (±5, ±10, ±15, ±20) of c and φ and the obtained values of confidence coefficients were compared. In addition, a comparison was made between different methods of stability analysis. According to the static and quasi-static conditions, Narmab dam is stable in all loading stages (End of Construction, First Impounding and Steady State Seepage and In general, only for the static conditions of the end of construction stage, the sensitivity of adhesion is greater than the angle of internal friction, but, in other conditions and stages, the sensitivity of friction angle has more effects.

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Timur, Mustafa, Hilmi Kuşçu, and Hayrettin Toylan. "Design and manufacture of automated controlled test machine detecting braking characteristic of brake lining in vehicles." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 18 (May 6, 2016): 3318–29. http://dx.doi.org/10.1177/0954406216645128.

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This study has been carried out in order to measure friction coefficient of friction materials used in autos through computer program. Variants such as speed, temperature, and pressure have been discussed and the effect of these variants on friction materials of autos. Variants such as speed, temperature, and pressure resulting from various effects in autos have been discussed, the effects of these variants on friction materials have been examined and their friction coefficients have been detected. In the test device whose manufacturing has been completed, temperature value between surface of brake lining and disc used during tests a machinery has been prepared in a way that temperature values are 0–400 ℃, speed values are 0–1400 rev/min, pressure values are 0–1.05 Mpa. In consideration of these dates, it has become possible to constitute friction coefficient–temperature, friction–time and temperature–time diagrams. By benefiting from the tests to be performed through friction coefficient test device, enhancement or progress will be ensured in material selection, technology and theory. Control pf parameters such as speed, temperature, pressure, force, and friction coefficient to be measured are performed easily through test device; moreover, thanks to electronically sensitivity of electronically and mechanical materials used in test device, it is ensured that you can reach the values you want to reach correctly. Friction tests have been carried out on samples having different properties in auto regulative test device. Friction coefficient values of automotive brake linings in the new system design and manufacturing which is carried out, have been in conformity with SAE-J661 Standard and TSE 555-9076 Standard (Turkish Standards Institution). Test results obtained are in parallel with the literature.

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Huynh, Le Hong Thai, and Pavel Němeček. "Sensitivity Analysis and Optimization Disc Brake by Stress Constraints." Applied Mechanics and Materials 52-54 (March 2011): 583–88. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.583.

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In recent years, a lot of studies on brake of car aims to reduce stress, vibration and noise of the brake on vehicle. In this paper presents a sensitivity analysis of pressure and friction coefficient effect to stress of disc brake. Base on this result, an optimization for brake by stress constraints was performed. The results are shown that the contact area between disc brake and pad also it’s stress and pressure. Studies also have shown relationships between pressure, friction coefficient and stress of brake. After that, we optimize the model of disc brake by stress constraints to obtain the new model better. This is a pre study for studies on dynamic and vibration of disc brake.

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Borstad, Christopher P., and D. M. McClung. "Sensitivity analyses in snow avalanche dynamics modeling and implications when modeling extreme events." Canadian Geotechnical Journal 46, no. 9 (September 2009): 1024–33. http://dx.doi.org/10.1139/t09-042.

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We present the first snow avalanche dynamics model simulations to start in the middle of the avalanche path at the maximum expected speed for an extreme event. We first present a sensitivity analysis of the dynamics model to the various model inputs. A single-parameter Coulomb-type friction formulation is used in the model. This formulation is supported by various experiments and full-scale observations of avalanche flow that demonstrate a coupling between the shear and normal forces in flowing snow. The dynamics model is shown to be most sensitive to changes in the friction coefficient. We suggest that the precision in the friction coefficient necessary to confidently use a dynamics model to predict runout distances is higher than the current state of knowledge about avalanche resistance mechanisms. This result leads to the new modeling technique that starts numerical simulations at the midpoint of the length of the avalanche path at maximum speed. The Coulomb friction coefficient is chosen to produce a unique speed profile from this new starting point at maximum speed to a state of rest at an empirically pre-determined runout position. The technique reproduces the observed sharp deceleration of avalanche flow in the runout zone.

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Zhou, Long, Jianqun Yu, Liusuo Liang, Yang Wang, Yajun Yu, Dongxu Yan, Kai Sun, and Ping Liang. "DEM Parameter Calibration of Maize Seeds and the Effect of Rolling Friction." Processes 9, no. 6 (May 22, 2021): 914. http://dx.doi.org/10.3390/pr9060914.

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A set of suitable parameter values is crucial in discrete element method (DEM) simulations. As a non-spherical particle, the coefficients of rolling friction between maize seed particles and between the seed particles and the boundary are hard to measure directly and must be obtained by calibration. In this paper, taking three representative maize varieties as research objects, the necessity for the accurate calibration of the coefficients of rolling friction between seed particles and between seed particles and boundaries is investigated. Subsequently, by studying the sensitivity of the coefficients of rolling friction between seed particles and between seed particles and the boundary to the angle of repose test, the methods used to calibrate the coefficients of rolling friction between seed particles and between the particles and the boundary are determined. It can be seen from the results that the coefficients of rolling friction between the seed particles and between the seed particles and the boundary have a significant influence on the test results, so these two parameters must be accurately calibrated. Additionally, the coefficient of rolling friction between seed particles and the boundary has no effect on the piling angle, but the piling angle is highly sensitive to the coefficient of rolling friction between seed particles. By comparing the simulation results and the experimental results in the lifting cylinder and “self-flow screening” tests, the calibrated seed parameters were found to be accurate and valid.

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Sofuoglu, Hasan, Hasan Gedikli, and Jahan Rasty. "Determination of Friction Coefficient by Employing the Ring Compression Test." Journal of Engineering Materials and Technology 123, no. 3 (September 13, 2000): 338–48. http://dx.doi.org/10.1115/1.1369601.

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The main objective of this research was to investigate the effect of material properties, strain-rate sensitivity, and barreling on the behavior of friction calibration curves. The compression tests were conducted to obtain the necessary material properties for the finite element analysis. A series of ring compression tests were then conducted in order to determine the magnitude of the friction coefficient, μ. The experiments were first conducted for the modeling materials, namely, white and black plasticine and later on, for aluminum, copper, bronze, and brass. The experiments were then simulated via an elastic-plastic finite element code (ABAQUS). Contrary to the results available in the literature, where the same friction calibration curves are recommended for all types of materials and test conditions, the results of this investigation showed that friction calibration curves are indeed affected by the material properties and test conditions.

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13

Haruff, J. P., C. J. Van Tyne, and D. K. Matlock. "The sensitivity of lab-measured friction coefficients." JOM 47, no. 7 (July 1995): 50–52. http://dx.doi.org/10.1007/bf03221232.

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Guzman, Leno J., Ying Chen, and Hubert Landry. "Discrete Element Modeling of Seed Metering as Affected by Roller Speed and Damping Coefficient." Transactions of the ASABE 63, no. 1 (2020): 189–98. http://dx.doi.org/10.13031/trans.13152.

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Abstract. The development of highly efficient seed metering is required to meet the demands of modern seeding equipment. The discrete element method (DEM) was used to simulate metering of seeds with a fluted roller meter. This approach was chosen due to its capability to accurately represent granular material flow. The contact model selected for the DEM simulation was the linear rolling resistance model. Angle of repose experimental tests and simulations were performed to calibrate the rolling friction coefficient for peas. The calibrated value for the rolling friction coefficient was 0.016. A 192 mm cross-section of an air cart seed roller and housing was defined as the domain of the simulation. Sensitivity analysis showed that simulated mass flow rates were not sensitive to the selected damping coefficients (0.2, 0.5, and 0.8). Sensitivity indicator values varied between -0.049 and 0.088 for the range of damping coefficients and roller speeds studied. The simulated geometry of the seed meter and housing resulted in a steady flow of seeds, with discharged mass increasing linearly. The simulated mass flow rates were 34.0, 72.3, 110.4, 147.3, and 182.0 g s-1 for roller speeds of 10, 20, 30, 40, and 50 rpm, respectively. An experiment was performed to validate the simulation results. The predicted mass flow rate values of the simulation were within 10 g s-1 of the experimental results, with the largest relative error being 16.5%. Keywords: DEM, Damping, Metering, Peas, Rolling friction coefficient, Seed, Simulation.

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Saptono, Singgih, and Danu Mirza Rezky. "Sensitivity analysis of nickel haul road embankment slopes using the coefficient of variation approach." Mining of Mineral Deposits 16, no. 3 (September 30, 2022): 48–53. http://dx.doi.org/10.33271/mining16.03.048.

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Purpose. The behavior of slope instability is influenced by many factors, both internal, such as the physical-mechanical properties of materials, and external, such as rain and seismic activity. Sensitivity analysis is used to determine the parameters that have the greatest impact on the level of slope stability. Methods. Sensitivity analysis of embankment slopes uses the coefficient of variation (CV) approach with input parameters namely cohesion and internal friction angle. Findings. The results of the study confirm that the internal friction angle is the most influential parameter on the embankment slope stability. The evidence is that at the highest percentage of CV, there is the highest probability of avalanches, based on these parameters. Originality. In this research, the coefficient of variation method is used to determine which parameters have heterogeneous data distribution and the greatest probability of failure, as well as to test mechanical sensitivity with the concept of changing the percentage of parameters to a safety factor value to validate calculations using the coefficient of variation approach. Practical implications. The sensitivity analysis results are not only limited to values, since the more important is finding out the cause of the influence of these parameters according to field conditions. The reason why the internal friction angle is the most sensitive parameter is the grain size approach, when the limestone mixture in the field has coarse and large grain sizes. Therefore, the surface tends to form rough waves and causes the relatively large grained rocks to have large internal friction angles.

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Wang, Fa Hui, and Ying Liu. "Effect of Composition on the Tribological Behaviors of Ceramic-Matrix Friction Materials." Advanced Materials Research 1061-1062 (December 2014): 645–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.645.

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The steel fiber reinforced ceramic matrix friction material is prepared by nitrogen protection sintering method. The specimens of the three different friction materials containing different content of alumina, clay and potash feldspar are formulated. The friction and wear characteristics are determined by using the XD-MSM constant speed friction tester. The testing results show that the increase of potash feldspar and the decrease of clay content make friction coefficient become more stable and diminish the sensitivity of friction coefficient to the temperature changes. This study also identify that among the three friction materials investigated, the main wear mechanism converts from grain pull-out and fracture wear to adhesion wear and abrasive wear.

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Kang, K., O. V. Zerkal, J. Liu, S. Huang, and D. Tao. "Comparison of Russian, Chinese and European seismic design on pseudo-static seismic coefficient in slope analysis." Journal of Civil Engineering and Construction 7, no. 2 (May 30, 2018): 57. http://dx.doi.org/10.32732/jcec.2018.7.2.57.

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Most design codes and specifications recommend a simple pseudo-static approach for the analysis of slope stability under seismic conditions. The codes in different countries appoint different pseudo-static seismic coefficient. The present work list different seismic coefficients in Russian, Chinese and European codes. A sensitivity analysis of a case slope was carried out using GeoStudio, then determined that the stability of the slope is more sensitive to material cohesion and seismic coefficient than material density and friction angle. It’s shown that the chosen of the seismic coefficient has a big effect on slope stability.

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Zhang, En, Fei Gao, Rong Fu, Yunzhuo Lu, Xiaoming Han, and Linlin Su. "Tribological Behavior of Phenolic Resin-Based Friction Composites Filled with Graphite." Materials 14, no. 4 (February 5, 2021): 742. http://dx.doi.org/10.3390/ma14040742.

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In this paper, the influence of graphite (Gr) on the dry sliding tribological properties of phenolic resin (PF) composites was studied under different sliding speeds of 3.1–47.1 m/s. The wear mechanism was investigated by the observation of the morphology of the transfer layer during the dry sliding process. It was found that the addition of Gr could decrease the friction coefficient and wear rate effectively, and the friction coefficient and wear rate decreased with the increase of Gr content in the range of 10–30 vol.%. The dominant wear mechanisms of PF-based friction composites changed from adhesive wear to fatigue wear (in the form of peeling-off) in the high sliding speed condition after the addition of Gr. The addition of Gr effectively reduced the sensitivity of PF-based friction materials to sliding speeds, and thus enhanced the stability of the friction coefficient. When the content of Gr was above 20 vol.%, the stability of the friction coefficient was relatively steady.

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Cheng, Gong, and Per Lötstedt. "Parameter sensitivity analysis of dynamic ice sheet models – numerical computations." Cryosphere 14, no. 2 (February 17, 2020): 673–91. http://dx.doi.org/10.5194/tc-14-673-2020.

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Abstract. The friction coefficient and the base topography of a stationary and a dynamic ice sheet are perturbed in two models for the ice: the full Stokes equations and the shallow shelf approximation. The sensitivity to the perturbations of the velocity and the height at the surface is quantified by solving the adjoint equations of the stress and the height equations providing weights for the perturbed data. The adjoint equations are solved numerically and the sensitivity is computed in several examples in two dimensions. A transfer matrix couples the perturbations at the base with the perturbations at the top. Comparisons are made with analytical solutions to simplified problems. The sensitivity to perturbations depends on their wavelengths and the distance to the grounding line. A perturbation in the topography has a direct effect at the ice surface above it, while a change in the friction coefficient is less visible there.

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Kwon, Hyuk Jae, and Cheol-Eung Lee. "Sensitivity analysis for friction coefficient on the estimations of probability of pipe breakage." KSCE Journal of Civil Engineering 13, no. 6 (September 18, 2009): 453–62. http://dx.doi.org/10.1007/s12205-009-0453-5.

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Aretz, Holger, and Frédéric Barlat. "Influence of Contact Friction on the Experimental Determination of the Balanced Biaxial Strain-Ratio Using the Disc Compression Test." Key Engineering Materials 611-612 (May 2014): 529–35. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.529.

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In the present work the disc compression test used to determine the balanced biaxial strain-ratio $r_b$ is analyzed in terms of the influence of contact friction using non-linear finite element analysis (FEA). The FEA results reveal an unexpectedly strong sensitivity of the $r_b$-value on contact friction, which is discussed in detail. The most important outcome of the present work is that the FEA can reproduce the $r_b$-value imposed by the utilized yield function very well, but only when the prescribed Coulomb friction coefficient has a very small value; for increasing friction coefficients a gradual deviation from the imposed $r_b$-value can be observed. This finding implies that in experiments contact friction must be eliminated to a larger extent than commonly expected, otherwise the determined $r_b$-value using disc compression testing will considerably deviate from the actual one, particularly when $r_b$ is far from one.

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Taureza, Muhammad, Sylvie Castagne, and Yingyot Aue-U-Lan. "Improving the Sensitivity of T-Shape Test to Friction Conditions for the Evaluation of Friction Behaviour in Microforming." Key Engineering Materials 447-448 (September 2010): 386–90. http://dx.doi.org/10.4028/www.scientific.net/kem.447-448.386.

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In this paper, the sensitivity of T-Shape test to friction conditions was evaluated by observing the extrusion height and load curves throughout the normalized stroke (relative to workpiece diameter). Using the finite element code Deform 2D and assuming plane strain approximation, the effects of changing die geometry to the T-Shape test results were investigated. The sensitivity of the T-Shape test was also improved by introducing the double-sloped T-Shape design. The double-sloped T-Shape test was able to separate the extrusion height curves for shear coefficient of friction 0.0 to 0.4 which was unable to distinguish using the original T-Shape setup.

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Simeonov, Julian A., K. Todd Holland, and Steven P. Anderson. "River Discharge and Bathymetry Estimation from Inversion of Surface Currents and Water Surface Elevation Observations." Journal of Atmospheric and Oceanic Technology 36, no. 1 (January 2019): 69–86. http://dx.doi.org/10.1175/jtech-d-18-0055.1.

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AbstractWe developed an approach for estimating river discharge and water depth from measurements of surface velocity and water surface elevation, based on analytical velocity–depth and velocity–slope relationships derived from the steady gravity–friction momentum balance and mass conservation. A key component in this approach is specifying the influence of bottom friction on the modeled depth-averaged flow. Accordingly, we considered two commonly used bottom friction parameterizations—a depth-independent Darcy friction coefficient and a depth-dependent friction coefficient based on the Manning’s roughness parameter. Assuming that the bottom friction coefficient is known, the unknown discharge was determined by minimizing the difference between the measured total head profile and the one determined from the velocity–slope relationship. The model performance and its sensitivity to key assumptions were evaluated using existing bathymetry data, and surface velocity and elevation observations obtained during field experiments on the Kootenai River near Bonners Ferry, Idaho, and the Hanford reach of the Columbia River. We found that the Manning’s friction parameterization provided superior depth and discharge estimates, compared to the Darcy friction law. For both steady and moderately unsteady flow, inversions based on the Manning’s friction provided discharge and thalweg depth estimates with relative errors not exceeding 5% and 12%, respectively.

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Schanner, Jonathan, Roman Funke, Andreas Schubert, and Alexander Hasse. "Investigating the Friction Behavior of Turn-Milled High Friction Surface Microstructures under Different Tribological Influence Factors." Journal of Manufacturing and Materials Processing 6, no. 6 (November 15, 2022): 143. http://dx.doi.org/10.3390/jmmp6060143.

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The coefficient of friction (COF) is an important parameter for mechanical engineers to consider when designing frictional connections. Previous work has shown that a surface microstructuring of the harder friction partner leads to a significant increase in the COF. However, the impact of the changes in the tribological system on the COF are not known in detail. In this study, the tribological influence factors such as the nominal surface pressure, the material pairing, lubrication, and the surface properties of the counterbody are investigated. Microstructuring is applied by turn-milling of an annular contact surface of cylindrical specimens. A torsional test bench is used to measure the torque depending on the displacement of the two specimens, thus enabling the determination of the COF. All tests with the microstructured specimens result in higher COF than the reference test with unstructured samples. The manufacturing process of the counterbody surface, the nominal surface pressure, and the materials in contact have a significant influence on the COF. While lubrication reduces friction in the case of unstructured specimens, the COF does not change significantly for microstructured samples. This proves that the deformative friction component dominates over the adhesive. Microstructuring the harder friction partner increases the transmittable torque in frictional connections and reduces the sensitivity towards possible contamination with lubricants.

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Adams, Michael J., Simon A. Johnson, Philippe Lefèvre, Vincent Lévesque, Vincent Hayward, Thibaut André, and Jean-Louis Thonnard. "Finger pad friction and its role in grip and touch." Journal of The Royal Society Interface 10, no. 80 (March 6, 2013): 20120467. http://dx.doi.org/10.1098/rsif.2012.0467.

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Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick–slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function.

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Zhang, Yahui, Wei Wang, and Huajiang Ouyang. "Dynamic reliability evaluation of vehicle–track coupled systems considering the randomness of suspension and wheel–rail parameters." Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability 233, no. 6 (July 24, 2019): 1106–21. http://dx.doi.org/10.1177/1748006x19863640.

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The ride quality and running safety of high-speed trains are directly influenced by uncertainties of some key parameters, such as the damping and stiffness coefficients of suspension systems, wheel–rail coefficient of friction and wheel–rail profiles. Dynamic reliability problems of vehicle–track coupled systems under the influence of the above random parameters are studied in this article. An efficient numerical method is presented by combining a prediction-based iterative solution technique with subset simulation method. The solution efficiency of deterministic responses is improved by means of efficient prediction of wheel–rail forces, and the number of deterministic solutions required is reduced by expressing a small failure probability as a product of large conditional probabilities. The accuracy and the efficiency of the present method are verified by comparing with the direct Monte Carlo simulation. The failure probability distribution curves of the lateral ride index on straight track and the derailment coefficient during curve negotiation are obtained and the reliability sensitivity analyses are also carried out. The main conclusions are given as follows: the reliability of the system is higher when the randomness of the parameters with greater sensitivity is not considered; the increase of the damping of anti-yaw damper or the wheel–rail coefficient of friction will improve the ride quality on straight track, but will lower the running safety when negotiating a curved track.

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Sethy, Ritanjali, Lander Galdos, Joseba Mendiguren, and Eneko Sáenz de Argandoña. "Identification of Friction Coefficient in Forging Processes by Means T-Shape Tests in High Temperature." Key Engineering Materials 716 (October 2016): 165–75. http://dx.doi.org/10.4028/www.scientific.net/kem.716.165.

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In hot metal bulk forming and forging, the interface heat transfer and the friction between the tooling and the billet are of particular importance since they have a significant effect on material flow, deformation, forming forces, component surface finish and die wear. Several authors have used different characterization methods to measure the friction coefficient using cylindrical upsetting tests, ring compression tests, Spike tests and T-Shape tests among others.In the present paper, The T-Shape test has been used in order to measure the friction between aluminium billets and tool steel. In order to obtain the sensitivity of the test, a Finite Element (FE) parametric study has been performed which indicates that shape of specimen could be chosen to measure the friction. For this, compression tests for three specimens in dry conditions have been carried out and shape of specimen has been measured. These measurements and the use of adequate inverse modelling techniques enabled a precise characterization of the forging friction coefficient. Heat transfer coefficient (HTC) has been precisely characterised from the columnar upsetting thermal tests and later used in simulating the T-Shape tests to estimate the friction factor (m). Friction factor has been determined by comparing the experimental results with the numerical simulation results of T-Shape compression test. An encouragingly good agreement has been found between the experimental and numerical results.

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Chi, Lu Lu, Jian Min Qin, and Xue Feng Chen. "DEM Simulation of Micro-Macro Mechanical Behaviour of Granular Materials." Advanced Materials Research 663 (February 2013): 441–46. http://dx.doi.org/10.4028/www.scientific.net/amr.663.441.

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The mechanical responses of granular materials are affected significantly by the properties of the individual particle. In order to establish the link between the micro and macro parameters, series of numerical biaxial simulations are carried out using two-dimensional discrete element method. The microscale mechanisms of mechanical behavior of granular materials are investigated through sensitivity analyses. The key influence of microscale parameters on the strength and deformation are discussed respectively. The peak strength depends on void ratio, friction coefficient and confining stress significantly. The elastic modulus is affected by friction coefficient, confining pressure and stiffness ratio, especially when the friction coefficient ranges from 0.1 to 0.3. The samples with different initial void ratio under the same loading condition can finally achieve the same critical state; the critical states at micro and macro scale are both independent of the initial void ratio.

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Mousavi, Hoda, and Corina Sandu. "Sensitivity analysis of tire-ice friction coefficient as affected by tire rubber compound properties." Journal of Terramechanics 91 (October 2020): 319–28. http://dx.doi.org/10.1016/j.jterra.2020.08.004.

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Li, Peng Fei, Tao Guo, and Zhong Yang Liu. "Finite Element Analysis of Parameters Sensitivity Analysis of Landslide Stability." Applied Mechanics and Materials 170-173 (May 2012): 903–6. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.903.

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On the basis of quantitative analysis, based on a real landslide of a specific profile of C, cohesion, internal friction angle and finite element mesh for landslide stability factor sensitivity. Through the analysis and calculation to determine the stability coefficient and the parameters related to changes in the relationship between, find out the effect on the stability of the most sensitive factors.

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Chang, Yuh Ping, Kuo Hsing Wang, Chao Hsien Lin, Chien Te Liu, and Yih Chyun Hwang. "A Technology of Using Surface Magnetization Variations for Evaluating the Wear-Resistant Properties of the Die Surfaces with Different TiN Films." Materials Science Forum 594 (August 2008): 377–82. http://dx.doi.org/10.4028/www.scientific.net/msf.594.377.

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Generally speaking, the major parameter which has been used to monitor the dynamic tribological properties of the films over the past decades is friction coefficient. However, it has shown low in sensitivity for many cases. Therefore, it is necessary to introduce more improved physical measurements other than the friction coefficient to monitor and control the film tribological characteristics in sliding contacts. In view of this, the novel technology of using instead surface magnetization variations for evaluating the wear-resistant properties of the films is proposed. The experiment was conducted by the pairs of SUS304 rubbing with SKD11 substrate with different TiN films (PVD and CVD) on the surface at different normal loads in dry friction process. According to the experimental results of the dynamic variations of surface magnetization and friction coefficient with the SEM observations of the wear tracks, the effects of normal loads on the friction and wear properties for the die surfaces with different TiN films can be investigated. The experimental results show that the continuous surface magnetization variations can be used to determine the timing of film fracture and the endurance life more accurately than that by the friction coefficient variations as usual. Therefore, the novel method of using surface magnetization variations does show great potentialities for evaluating the tribological properties of the die surfaces with different TiN films.

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Peng, Huachen, Wencheng Tang, and Xin Zhou. "Sensitivity analysis of Johnson-Cook material constants and friction coefficient to the surface residual maximum principal stress in turning Inconel 718 simulations." Journal of Physics: Conference Series 2321, no. 1 (August 1, 2022): 012005. http://dx.doi.org/10.1088/1742-6596/2321/1/012005.

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Abstract The residual maximum principal stress on the surface of components affects the service life and corrosion resistance of parts. The current study focuses on the sensitivities of the Johnson-Cook (JC) constitutive constants and the friction coefficient to the surface residual maximum principal stress during turning Inconel 718 with low-level and high-level cutting parameters. Two sets of three-dimensional (3D) turning simulations and experiments are carried out under low-level and high-level cutting parameters to verify the credibility of the simulation parameter settings. Then, the above sensitivities are analyzed based on eighteen sets of 3D turning simulations designed by the Taguchi approach. When the cutting parameters are low-level, the strain hardening coefficient B is highly sensitive to the residual maximum principal stress. Besides, under high-level cutting parameters, the strain hardening coefficient B, the strain hardening index n and the thermal softening coefficient m have high sensitivities, in which the thermal softening coefficient m is the most sensitive, followed by the strain hardening coefficient B. The present work provides a direction for studying the influence of surface residual maximum principal stress on the service life of components by adjusting the JC constitutive constants and the friction coefficient.

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Lugwig, Wojciech. "Impact of friction coefficient on particles circulation velocity calculated by euler-lagrange model in spouted bed apparatus for dry coating." Technical Sciences 4, no. 21 (November 21, 2018): 303–21. http://dx.doi.org/10.31648/ts.4175.

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This paper is a continuation of research concerning gas-solid flow modelling using the Euler-Lagrange approach in a spout-fluid bed apparatus. The major challenge in this case was to determine the friction coefficient for particles hitting against the walls of the apparatus. On the basis of the properties of similar materials the value of this quantity was estimated at 0.2. Therefore, it proved useful to check the model’s sensitivity to the value of this parameter. The study investigated the effect of friction coefficient on calculated values of particles velocity in the draft tube and the annular zone of the device for various volumes of the circulating bed. In the course of calculations, a relatively small influence of friction coefficient on particles velocity was observed in the tested zones of the apparatus. The changes were most visible for large volumes of the bed, which was connected with an increase in the number of collisions of particles with the walls.

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34

Yevtushenko, Aleksander, Michal Kuciej, Ewa Och, and Olena Yevtushenko. "Effect of the thermal sensitivity in modeling of the frictional heating during braking." Advances in Mechanical Engineering 8, no. 12 (December 2016): 168781401668174. http://dx.doi.org/10.1177/1687814016681744.

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The influence of the thermal sensitivity of a coefficient of friction and thermophysical properties of the pad and disk materials on the temperature distribution during single braking has been studied. For this purpose, the corresponding one-dimensional thermal problem of friction at braking has been formulated. The solution to such nonlinear problem has been made in two stages. First, the partial linearization was carried out using Kirchhoff’s substitution, and then, the initial problem for a system of nonlinear ordinary differential equations was obtained by method of lines. Numerical solution to problem was received by Adams’ method realized in the DIFSUB package. For a friction pair, disk (steel)–pad (retinax), an analysis of the evolution of sliding speed and temperature was carried out. The results obtained within the model that took into account the mutual influence between the speed and temperature were compared with those obtained without taking into account such effects.

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Yevtushenko, Aleksander, Katarzyna Topczewska, and Przemysław Zamojski. "Temperature during Repetitive Short-Term Operation of a Brake with Functionally Graded Friction Element." Materials 16, no. 2 (January 16, 2023): 881. http://dx.doi.org/10.3390/ma16020881.

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The object of study is the temperature of a braking system, operating in repetitive short-term (RST) mode. One element of the considered friction pair is made of a functionally gradient material (FGM), and the other of a homogeneous material. To determine the temperature on the friction surfaces of both elements, the previously obtained, exact solution of the boundary value problem of heat conduction was adopted, with account of the heat generation due to the friction. A calculation scheme was proposed that takes into consideration thermal sensitivity of materials and variations of the friction coefficient under the influence of temperature. Calculations were performed for two-component FGM (ZrO2–Ti-6Al-4V) in combination with gray cast iron (ChNMKh). It was found that for selected friction pair materials, consideration of their thermal sensitivity reduces the time of braking and the value of temperature achieved on the friction surfaces. At the same time, the whole process was characterized by a good stability of braking with a slight decrease in efficiency in each subsequent cycle.

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Eriksen, Rasmus Solmer, M. Calaon, Mogens Arentoft, and Nils Bay. "Benchmarking of Direct and Indirect Friction Tests in Micro Forming." Key Engineering Materials 504-506 (February 2012): 581–86. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.581.

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In this study the application of a simulative sliding friction test at micro scale is suggested. Two work piece specimens are upset against opposing sides of a flat tool element. The tool element is then pulled out while the resulting friction force F is measured. The test principle offers several advantages when compared against the DEC-test, including easy visual inspection of tool and work piece surfaces, continuous measurement of friction coefficient over the complete sliding length and less sensitivity to mechanical tolerance deviations of work piece and tool elements.

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Bilaloglu, Seda, Ying Lu, Daniel Geller, John Ross Rizzo, Viswanath Aluru, Esther P. Gardner, and Preeti Raghavan. "Effect of blocking tactile information from the fingertips on adaptation and execution of grip forces to friction at the grasping surface." Journal of Neurophysiology 115, no. 3 (March 1, 2016): 1122–31. http://dx.doi.org/10.1152/jn.00639.2015.

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Adaptation of fingertip forces to friction at the grasping surface is necessary to prevent use of inadequate or excessive grip forces. In the current study we investigated the effect of blocking tactile information from the fingertips noninvasively on the adaptation and efficiency of grip forces to surface friction during precision grasp. Ten neurologically intact subjects grasped and lifted an instrumented grip device with 18 different frictional surfaces under three conditions: with bare hands or with a thin layer of plastic (Tegaderm) or an additional layer of foam affixed to the fingertips. The coefficient of friction at the finger-object interface of each surface was obtained for each subject with bare hands and Tegaderm by measuring the slip ratio (grip force/load force) at the moment of slip. We found that the foam layer reduced sensibility for two-point discrimination and pressure sensitivity at the fingertips, but Tegaderm did not. However, Tegaderm reduced static, but not dynamic, tactile discrimination. Adaptation of fingertip grip forces to surface friction measured by the rate of change of peak grip force, and grip force efficiency measured by the grip-load force ratio at lift, showed a proportional relationship with bare hands but were impaired with Tegaderm and foam. Activation of muscles engaged in precision grip also varied with the frictional surface with bare hands but not with Tegaderm and foam. The results suggest that sensitivity for static tactile discrimination is necessary for feedforward and feedback control of grip forces and for adaptive modulation of muscle activity during precision grasp.

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Huang, Jinchun, Charles M. Krousgrill, and Anil K. Bajaj. "An Efficient Approach to Estimate Critical Value of Friction Coefficient in Brake Squeal Analysis." Journal of Applied Mechanics 74, no. 3 (June 13, 2006): 534–41. http://dx.doi.org/10.1115/1.2423037.

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Automotive brake squeal generated during brake applications has become a major concern in automotive industry. Warranty costs for brake noise related complaints have been greatly increasing in recent years. Brake noise and vibration control are also important for the improvement of vehicle quietness and passenger comfort. In this work, the mode coupling instability mechanism is discussed and a method to estimate the critical value of friction coefficient identifying the onset of brake squeal is presented. This is achieved through a sequence of steps. In the first step, a modal expansion method is developed to calculate eigenvalue and eigenvector sensitivities. Different types of mode couplings and their relationships with possible onset of squeal are discussed. Then, a reduced-order characteristic equation method based on the elastically coupled system eigenvalues and their derivatives is presented to estimate the critical value of friction coefficient. The significance of this method is that the critical value of friction coefficient can be predicted accurately without the need for a full complex eigenvalue analysis, making it possible to determine the sensitivity of system stability with respect to design parameters directly.

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Zhu, Enze, Zhipeng Zhang, and Hong Nie. "Sensitivity Analysis of Holdback Bar Release Load during Catapult-Assisted Takeoff of Carrier-Based Aircraft." Applied Sciences 12, no. 2 (January 13, 2022): 785. http://dx.doi.org/10.3390/app12020785.

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The release load of holdback bar will affect the safety of catapult-assisted takeoff of carrier-based aircraft, and the accurate control of releasing the load will ensure success. The magnitude and the control accuracy of release load are important parameters which impact the takeoff performance, therefore unstable release load and insufficient release precision are the main factors affecting the takeoff safety. In this paper, mechanical models of the carrier-based aircraft in the catapult-assisted takeoff tensioning state and gliding state after release are established based on multi-body dynamics, contact mechanics and tribological theory, and the influence of the release load of the holdback bar on the catapult-assisted takeoff performance is analyzed. Furthermore, a kinetic model of the holdback bar device is established, and the kinetic characteristics of the release process of the holdback bar are studied. Based on the kinetic model and friction model of the holdback bar, the influencing factors of the sensitivity of the holdback bar release load are analyzed and the structural parameters are optimized. The results show that the released load decreases slowly with the increase of the contact surface angle of the holdback bar structure and increases rapidly when that angle reaches the critical value; besides, the release load increases slowly with the increase of the friction coefficient of the contact surface and increases faster when the critical friction coefficient is reached.

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Jin, Yun Xue, Qiang Qiang Tong, Xiao Ya Wang, and Hong Mei Chen. "Effect of T6 Heat Treatment on Dry Sliding Frictional Wear Characteristics of Al-20Si-5Cu Alloy." Advanced Materials Research 750-752 (August 2013): 591–95. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.591.

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The effect of T6 heat treatment on dry sliding friction and wear characteristics of Al-20Si-5Cu under a fixed sliding speed of 200r/min and sliding time of 30mins was illustrated in this paper. The result reveals that T6 heat treatment can improve morphology of primary Si and Al2Cu particles, enhance the hardness of the matrix. Wear rate increased with increasing of applied load. T6 heat treated samples have high wear resistance which is related to the improvement of microstructure, particularly with their increased hardness of matrix. But friction coefficient varies with heat treatment processes and has no sensitivity to applied loads, which fluctuates in a small range, so the friction coefficient can be considered to be stable. The wear mechanisms of T6 heat treated samples are also changed with increasing of applied load, from oxidative wear to fatigue wear.

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Chen, Fang Fang, Zhi Qiang Zhang, and Ning Li. "Sensitivity Analysis of the Influences of Rock Mechanical Parameters on the Deformation of Underground Caverns." Applied Mechanics and Materials 275-277 (January 2013): 262–68. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.262.

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The Main factors affecting the stability of underground caverns are selected, including the rock mechanical parameters (elastic modulus, Poisson ratio, cohesion and internal friction angle) and initial ground stress parameter (lateral pressure coefficient). Numerical test method is adopted to analyze each parameter’s sensitivity to surrounding rock displacement. Sensitivity formula making each values comparable is established. The sensitivity distribution laws are obtained, and then each parameter’s quantitative effect on displacement is discussed. This work has prominent guiding significance to engineering designs.

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Zhang, Tingting, Xiangfeng Guo, Julien Baroth, and Daniel Dias. "Metamodel-Based Slope Reliability Analysis—Case of Spatially Variable Soils Considering a Rotated Anisotropy." Geosciences 11, no. 11 (November 9, 2021): 465. http://dx.doi.org/10.3390/geosciences11110465.

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A rotation of the anisotropic soil fabric pattern is commonly observed in natural slopes with a tilted stratification. This study investigates the rotated anisotropy effects on slope reliability considering spatially varied soils. Karhunen–Loève expansion is used to generate the random fields of the soil shear strength properties (i.e., cohesion and friction angle). The presented probabilistic analyses are based on a meta-model combining Sparse Polynomial Chaos Expansion (SPCE) and Global Sensitivity Analysis (GSA). This method allows the number of involved random variables to be reduced and then the computational efficiency to be improved. Two kinds of deterministic models, namely a discretization kinematic approach and a finite element limit analysis, are considered. A variety of valuable results (i.e., failure probability, probability density function, statistical moments of model response, and sensitivity indices of input variables) can be effectively provided. Moreover, the influences of the rotated anisotropy, autocorrelation length, coefficient of variation and cross-correlation between the cohesion and friction angle on the probabilistic analysis results are discussed. The rotation of the anisotropic soil stratification has a significant effect on the slope stability, particularly for the cases with large values of autocorrelation length, coefficient of variation, and cross-correlation coefficient.

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Liu, Jinhao, Jianhua Wu, Yusheng Zhang, and Xinhao Wu. "Sensitivity Analysis of Hydraulic Transient Simulations Based on the MOC in the Gravity Flow." Water 13, no. 23 (December 6, 2021): 3464. http://dx.doi.org/10.3390/w13233464.

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The purpose of this study was to evaluate the sensitivity of input parameters to output results when using the method of characteristics (MOC) for hydraulic transient simulations. Based on a gravity flow water delivery project, we selected six main parameters that affect the hydraulic transient simulation and selected maximum pressure as the output parameter in order to perform a parameter sensitivity analysis. The Morris sensitivity analysis (Morris) and the partial rank correlation coefficient method based on Latin hypercube sampling (LHS-PRCC) were both adopted. The results show that the sensitivity of each parameter is the same except for the friction factor. The flow rate and Young’s modulus are positively correlated with the maximum pressure, whereas the pipe diameter, valve closing time, and wall thickness are negatively correlated. It is discussed that the variability of the friction factor comes from the function of the flow and pressure regulating valve. When other conditions of the gravity flow project remain unchanged, the maximum pressure increases with the increase in the friction factor. The flow rate, pipe diameter, and valve closing time are the key parameters that affect the model. Meanwhile, Morris and LHS-PRCC proved to be effective methods for evaluating parameter sensitivity in hydraulic transient simulations.

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Fiorentino, Antonio, Elisabetta Ceretti, and Claudio Giardini. "The THF Compression Test for Friction Estimation: Study on the Influence of the Tube Material." Key Engineering Materials 549 (April 2013): 423–28. http://dx.doi.org/10.4028/www.scientific.net/kem.549.423.

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In the Tube Hydroforming (THF) process, a tube, placed in closed dies, is expanded by a high pressure liquid and two punches push its edges in order to feed the material into the expansion zones. Because of the high pressure and the contact area involved in the process, high friction stresses act on the tube walls restricting the material flow so reducing the amount of fed material, the part formability and affecting the soundness of the final part and its geometry. In fact, previous studies showed that the lower the friction coefficient at the tube-die interface, the more uniform the friction distribution and, therefore, the more uniform the stresses acting on the tube walls. The tube deformation being dependent on the stresses, its final thickness is influenced by friction. Starting from this premise, the authors proposed a reference test which is able to highlight the effect of friction on the final tube thickness. In this test, namely the THF Compression Test, a tube is placed in a cylindrical die having the same diameter as the outside of the tube, it is pressurized and then compressed by the punches. In this way, the tube has no expansion and its final thickness depends on the process parameters (tube material, pressure, punch stroke, tube material and geometry). Using FE simulations, it is possible to express the friction coefficient as a function of the process conditions and to use it in combination with experimental results. In the present paper, the previously validated FE model is used to investigate the influence of the tube material on the compression test results. Therefore, a simulation study was performed using different values of strength and hardening coefficients showing how the method is affected by the tested material thereby giving further indication of the test sensitivity.

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HIROSE, Kiyoshi, and Akiko KONDO. "A Study on Estimation Method of Friction Coefficient in Skin-Material Using High Sensitivity Force Plate." Proceedings of Mechanical Engineering Congress, Japan 2020 (2020): J23508. http://dx.doi.org/10.1299/jsmemecj.2020.j23508.

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Recklin, Viktor, Florian Dietrich, and Peter Groche. "Influence of Test Stand and Contact Size Sensitivity on the Friction Coefficient in Sheet Metal Forming." Lubricants 6, no. 2 (April 27, 2018): 41. http://dx.doi.org/10.3390/lubricants6020041.

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47

Huang, Jinchun, Charles M. Krousgrill, and Anil K. Bajaj. "An efficient approach to estimate critical value of friction coefficient and sensitivity analysis for brake squeal." International Journal of Vehicle Design 51, no. 1/2 (2009): 21. http://dx.doi.org/10.1504/ijvd.2009.027114.

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Zhao, Chen, Rupert M. Gladstone, Roland C. Warner, Matt A. King, Thomas Zwinger, and Mathieu Morlighem. "Basal friction of Fleming Glacier, Antarctica – Part 1: Sensitivity of inversion to temperature and bedrock uncertainty." Cryosphere 12, no. 8 (August 15, 2018): 2637–52. http://dx.doi.org/10.5194/tc-12-2637-2018.

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Abstract. Many glaciers in the Antarctic Peninsula are now rapidly losing mass. Understanding of the dynamics of these fast-flowing glaciers, and their potential future behaviour, can be improved through ice sheet modelling studies. Inverse methods are commonly used in ice sheet models to infer the spatial distribution of a basal friction coefficient, which has a large effect on the basal velocity and ice deformation. Here we use the full-Stokes Elmer/Ice model to simulate the Wordie Ice Shelf–Fleming Glacier system in the southern Antarctic Peninsula. With an inverse method, we infer the pattern of the basal friction coefficient from surface velocities observed in 2008. We propose a multi-cycle spin-up scheme to reduce the influence of the assumed initial englacial temperature field on the final inversion. This is particularly important for glaciers like the Fleming Glacier, which have areas of strongly temperature-dependent deformational flow in the fast-flowing regions. Sensitivity tests using various bed elevation datasets, ice front positions and boundary conditions demonstrate the importance of high-accuracy ice thickness/bed geometry data and precise location of the ice front boundary.

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Ganesh, P., and V. S. Senthil Kumar. "Numerical Analysis on Superplastic Forming of Friction Stir Welded AA6061-T6 Alloy Sheet." Advanced Materials Research 488-489 (March 2012): 753–58. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.753.

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The friction stir welded superplastic forming of AA6061-T6 sheet has been numerically analyzed based on the experimental and finite element software. A selected range of tool rotating speeds of 500, 1000 and 2000 rpm was used for friction stir welding. At constant temperature of 550O C and constant pressure of 0.4 Mpa, superplastic forming experiments was performed using free forming die for the friction stir welded sheets. A detailed 3D element type study has been performed in the finite element analysis. The proposed finite element model has been validated in comparison with experimental data. The results are found to have reasonably good agreement between simulations and experiment. The effect of constant pressure, coefficient of friction, strainrate and strain-rate sensitivity has been studied using the proposed finite element model.

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Yevtushenko, Aleksander, Katarzyna Topczewska, and Michal Kuciej. "Analytical Determination of the Brake Temperature Mode during Repetitive Short-Term Braking." Materials 14, no. 8 (April 11, 2021): 1912. http://dx.doi.org/10.3390/ma14081912.

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An algorithm to determine the maximum temperature of brake systems during repetitive short-term (RST) braking mode has been proposed. For this purpose, the intermittent mode of braking was given in the form of a few cyclic stages consisting of subsequent braking and acceleration processes. Based on the Chichinadze’s hypothesis of temperature summation, the evolutions of the maximum temperature during each cycle were calculated as the sum of the mean temperature on the nominal contact surface of the friction pair elements and temperature attained on the real contact areas (flash temperature). In order to find the first component, the analytical solution to the one-dimensional thermal problem of friction for two semi-spaces taking into account frictional heat generation was adapted. To find the flash temperature, the solution to the problem for the semi-infinite rod sliding with variable velocity against a smooth surface was used. In both solutions, the temperature-dependent coefficient of friction and thermal sensitivity of materials were taken into account. Numerical calculations were carried out for disc and drum brake systems. The obtained temporal variations of sliding velocity, friction power and temperature were investigated on each stage of braking. It was found that the obtained results agree well with the corresponding data established by finite element and finite-difference methods.

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Journal articles on the topic 'Sensitivity to the friction coefficient'

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