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Journal articles on the topic 'Contact forces'

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Author: Grafiati

Published: 4 June 2021

Last updated: 20 February 2023

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1

Anglin, C., U. P. Wyss, and D. R. Pichora. "Glenohumeral contact forces." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 214, no. 6 (June 2000): 637–44. http://dx.doi.org/10.1243/0954411001535660.

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2

Adams, G. G., and M. Nosonovsky. "Contact modeling — forces." Tribology International 33, no. 5-6 (May 2000): 431–42. http://dx.doi.org/10.1016/s0301-679x(00)00063-3.

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3

Hao, Huang Wen. "Electrostatic and contact forces in force microscopy." Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 9, no. 2 (March 1991): 1323. http://dx.doi.org/10.1116/1.585188.

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4

Yang, R., R. Miller, and P. J. Bryant. "Atomic force profiling by utilizing contact forces." Journal of Applied Physics 63, no. 2 (January 15, 1988): 570–72. http://dx.doi.org/10.1063/1.340089.

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5

Petrov, E. P., and D. J. Ewins. "Effects of Damping and Varying Contact Area at Blade-Disk Joints in Forced Response Analysis of Bladed Disk Assemblies." Journal of Turbomachinery 128, no. 2 (September 28, 2005): 403–10. http://dx.doi.org/10.1115/1.2181998.

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An approach is developed to analyze the multiharmonic forced response of large-scale finite element models of bladed disks taking account of the nonlinear forces acting at the contact interfaces of blade roots. Area contact interaction is modeled by area friction contact elements which allow for friction stresses under variable normal load, unilateral contacts, clearances, and interferences. Examples of application of the new approach to the analysis of root damping and forced response levels are given and numerical investigations of effects of contact conditions at root joints and excitation levels are explored for practical bladed disks.

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6

Ahmed, Rizwan, Christian Maria Firrone, and Stefano Zucca. "Design and Calibration of a Tri-Directional Contact Force Measurement System." Applied Sciences 11, no. 2 (January 19, 2021): 877. http://dx.doi.org/10.3390/app11020877.

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In low pressure turbine stages, adjacent blades are coupled to each other at their tip by covers, called shrouds. Three-dimensional periodic contact forces at shrouds strongly affect the blade vibration level as energy is dissipated by friction. To validate contact models developed for the prediction of nonlinear forced response of shrouded blades, direct contact force measurement during dynamic tests is mandatory. In case of shrouded blades, the existing unidirectional and bi-directional contact force measurement methods need to be improved and extended to a tri-directional measurement of shroud contact forces for a comprehensive and more reliable validation of the shroud contact models. This demands an accurate and robust measurement solution that is compatible with the nature and orientation of the contact forces at blade shrouds. This study presents a cost effective and adaptable tri-directional force measurement system to measure static and dynamic contact forces simultaneously in three directions at blade shrouds during forced response tests. The system is based on three orthogonal force transducers connected to a reference block that will eventually be put in contact with the blade shroud in the test rig. A calibration process is outlined to define a decoupling matrix and its subsequent validation is demonstrated in order to evaluate the effectiveness of the measurement system to measure the actual contact forces acting on the contact.

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7

McClelland, John A. "Contact and field forces." Physics Teacher 37, no. 9 (December 1999): 516. http://dx.doi.org/10.1119/1.880385.

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8

Yang, B. D., and C. H. Menq. "Modeling of Friction Contact and Its Application to the Design of Shroud Contact." Journal of Engineering for Gas Turbines and Power 119, no. 4 (October 1, 1997): 958–63. http://dx.doi.org/10.1115/1.2817082.

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Designers of aircraft engines frequently employ shrouds in turbine design. In this paper, a variable normal load friction force model is proposed to investigate the influence of shroudlike contact kinematics on the forced response of frictionally constrained turbine blades. Analytical criteria are formulated to predict the transitions between stick, slip, and separation of the interface so as to assess the induced friction forces. When considering cyclic loading, the induced friction forces are combined with the variable normal load so as to determine the effective stiffness and damping of the friction joint over a cycle of motion. The harmonic balance method is then used to impose the effective stiffness and damping of the friction joint on the linear structure. The solution procedure for the nonlinear response of a two-degree-of-freedom oscillator is demonstrated. As an application, this procedure is used to study the coupling effect of two constrained forces, friction force and variable normal load, on the optimization of the shroud contact design.

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9

Xiong, Cai-Hua, Michael Yu Wang, Yong Tang, and You-Lun Xiong. "On the prediction of passive contact forces of workpiece-fixture systems." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 219, no. 3 (March 1, 2005): 309–24. http://dx.doi.org/10.1243/095440505x30159.

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The prediction of passive forces in a frictional workpiece-fixture system is an important problem, since the contact forces have a strong influence on clamp design and on workpiece accuracy during machining. This paper presents a general method for the computation of passive contact forces. Firstly, an indeterminate system of static equilibrium is defined, in which the passive, frictional contact forces cannot be determined arbitrarily as in an actively controlled robotic multifinger grasp. Then, a locally elastic contact model is used to describe the non-linear coupling between the contact forces and elastic deformations at the contact point. This model captures the essence of the passive contact. Further, a set of ‘compatibility’ equations is given so that the relationship can be developed between the elastic deformations at all contacts and the displacement of the workpiece. Finally, combining the force equilibrium, the locally elastic contact model and the ‘compatibility’ conditions, the passive force computation problem is transformed into a determinate system of non-linear equations governing all of the elastic deformations at all of the passive contacts. By solving the resulting non-linear equations, all passive contact forces can be accurately predicted in the frictional workpiece-fixture system. This method is illustrated with example cases. The method presented here may also have an application to other passive, indeterminate problems such as power grasps in robotics.

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10

Petrov, E. P. "Method for Direct Parametric Analysis of Nonlinear Forced Response of Bladed Disks With Friction Contact Interfaces." Journal of Turbomachinery 126, no. 4 (October 1, 2004): 654–62. http://dx.doi.org/10.1115/1.1776588.

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An effective method for direct parametric analysis of periodic nonlinear forced response of bladed disks with friction contact interfaces has been developed. The method allows, forced response levels to be calculated directly as a function of contact interface parameters such as the friction coefficient, contact surface stiffness (normal and tangential coefficients), clearances, interferences, and the normal stresses at the contact interfaces. The method is based on exact expressions for sensitivities of the multiharmonic interaction forces with respect to variation of all parameters of the friction contact interfaces. These novel expressions are derived in the paper for a friction contact model, accounting for the normal load variation and the possibility of separation-contact transitions. Numerical analysis of effects of the contact parameters on forced response levels has been performed using large-scale finite element models of a practical bladed turbine disk with underplatform dampers and with shroud contacts.

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11

Dumont, Serge, Jerôme Fortin, and Youssef Ouafik. "Polarization of contact forces in multi-contact systems." European Journal of Computational Mechanics 19, no. 1-3 (January 2010): 77–88. http://dx.doi.org/10.3166/ejcm.19.77-88.

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12

Rahman, Fazlar, and M. A. Salam Akanda. "Numerical analysis of reaction forces at the supports of sliding microwire." Journal of Mechanical Engineering and Sciences 14, no. 4 (May 26, 2022): 7434–45. http://dx.doi.org/10.15282/jmes.14.4.2020.12.0586.

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The reaction forces at the tungsten support probes of a platinum microwire are determined by numerical analysis for different push-pull sliding velocities and contact pressures. The Finite Element Analysis (FEA) tool ANSYS Workbench is used to evaluate the contact stresses, reaction forces and deformations of the platinum microwire. The nonlinear contact analysis and contact formulations are implemented to ensure that the platinum microwire maintained contact with the tungsten support probes during push-pull sliding motion, and transfer frictional forces between contact surfaces without penetration and separation. The reaction forces at the support probes are found independent of the sliding velocity of the platinum microwire and vary with normal contact pressure. The results found in the numerical analysis are validated through experimental works. Due to the tiny size, the nonlinearity of contacts and indeterminate supports criteria, it is difficult to determine the reaction forces at the supports of a sliding microwire by conventional mechanics. The method of the numerical analysis of the sliding microwire presented in this paper can be used to determine the reaction forces of other microstructures, validate the experimental results, as well as to evaluate total disturbance forces in the microstructures where relative motion exists; which are important for the proper design and failure analysis of the MEMS devices and microstructures.

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13

Byers, John, Denis Cohen, and Neal R. Iverson. "Subglacial clast/bed contact forces." Journal of Glaciology 58, no. 207 (2012): 89–98. http://dx.doi.org/10.3189/2012jog11j126.

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AbstractA laboratory device was built to measure the forces that ice exerts on a 0.05 m diameter rigid plastic sphere in two different configurations: in contact with a flat bed or isolated from the bed. Measurements indicated that bed-normal contact forces were 1.8 times larger than drag forces due to creeping flow past a slippery sphere isolated from the bed. Measurements of forces as a function of the bed-normal ice velocity, estimations of the ice viscosity parameter and observations of markers in the ice indicate ice is Newtonian with a viscosity of ~1.3x 1011 Pas. Newtonian behavior is expected due to small and transient stresses. A model of regelation indicates that it had a negligible (<5%) influence on forces. Water pressure in the cavity beneath the sphere in contact with the bed had a likewise negligible influence on contact forces. When no cavity is present, drag forces can be correctly estimated using Stokes’s law (Newtonian viscosity) for a slippery sphere. The same law with a bed-enhancement factor of 1.8 is appropriate for estimating bed-normal contact forces. These results reinforce previous laboratory measurements and theories but provide no support for explanations of high debris/bed friction or rates of abrasion that depend on high contact forces.

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14

Takato, Yoichi, Michael E. Benson, and Surajit Sen. "Small nanoparticles, surface geometry and contact forces." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, no. 2211 (March 2018): 20170723. http://dx.doi.org/10.1098/rspa.2017.0723.

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In this molecular dynamics study, we examine the local surface geometric effects of the normal impact force between two approximately spherical nanoparticles that collide in a vacuum. Three types of surface geometries—(i) crystal facets, (ii) sharp edges, and (iii) amorphous surfaces of small nanoparticles with radii R <10 nm—are considered. The impact forces are compared with their macroscopic counterparts described by nonlinear contact forces based on Hertz contact mechanics. In our simulations, edge and amorphous surface contacts with weak surface energy reveal that the average impact forces are in excellent agreement with the Hertz contact force. On the other hand, facet collisions show a linearly increasing force with increasing compression. Our results suggest that the nearly spherical nanoparticles are likely to enable some nonlinear dynamic phenomena, such as breathers and solitary waves observed in granular materials, both originating from the nonlinear contact force.

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15

Sainte-Claire Deville, Arnaud. "Des forces terrestres au contact." Revue Défense Nationale N° 780, no. 5 (May 1, 2015): 11–14. http://dx.doi.org/10.3917/rdna.780.0011.

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16

Larsson, Krister, Stephane Barrelet, and Wolfgang Kropp. "Modeling of tangential contact forces." Journal of the Acoustical Society of America 103, no. 5 (May 1998): 2920. http://dx.doi.org/10.1121/1.422112.

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17

Seo, Jang Ho, and Hong Soon Choi. "Computation of Magnetic Contact Forces." IEEE Transactions on Magnetics 50, no. 2 (February 2014): 525–28. http://dx.doi.org/10.1109/tmag.2013.2283106.

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18

Churaev, N. V. "Contact angles and surface forces." Advances in Colloid and Interface Science 58, no. 2-3 (July 1995): 87–118. http://dx.doi.org/10.1016/0001-8686(95)00245-l.

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19

Fazeli, Nima, Roman Kolbert, Russ Tedrake, and Alberto Rodriguez. "Parameter and contact force estimation of planar rigid-bodies undergoing frictional contact." International Journal of Robotics Research 36, no. 13-14 (April 1, 2017): 1437–54. http://dx.doi.org/10.1177/0278364917698749.

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This paper addresses the identification of the inertial parameters and the contact forces associated with objects making and breaking frictional contact with the environment. Our goal is to explore under what conditions, and to what degree, the observation of physical interaction, in the form of motions and/or applied external forces, is indicative of the underlying dynamics that governs it. In this study we consider the cases of passive interaction, where an object free-falls under gravity, and active interaction, where known external perturbations act on an object at contact. We assume that both object and environment are planar and rigid, and exploit the well-known complementarity formulation for contact resolution to establish a constrained optimization-based problem to estimate inertial parameters and contact forces. We also show that when contact modes are known, or guessed, the formulation provides a closed-form relationship between inertial parameters, contact forces, and observed motions, that turns into a least squares problem. Consistent with intuition, the analysis indicates that without the application of known external forces, the identifiable set of parameters remains coupled, i.e. the ratio of mass moment of inertia to mass and the ratio of contact forces to the mass. Interestingly the analysis also shows that known external forces can lead to decoupling and identifiability of mass, mass moment of inertia, and normal and tangential contact forces. We evaluate the proposed algorithms both in simulation and with real experiments for the cases of a free falling square, ellipse, and rimless wheel interacting with the ground, as well as a disk interacting with a manipulator.

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20

Adams, George G., Sinan Mu¨ftu¨, and Nazif Mohd Azhar. "A Scale-Dependent Model for Multi-Asperity Contact and Friction." Journal of Tribology 125, no. 4 (September 25, 2003): 700–708. http://dx.doi.org/10.1115/1.1573232.

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As loading forces decrease in applications such as MEMS and NEMS devices, the size of the asperity contacts which comprise the real contact area tend to decrease into the nano scale regime. This reduction in size of the contacts is only partially offset by the nominally increased smoothness of these contacting surfaces. Because the friction force depends on the real area of contact, it is important to understand how the material and topographical properties of surfaces contribute to friction forces at this nano scale. In this investigation, the single asperity nano contact model of Hurtado and Kim is incorporated into a multi-asperity model for contact and friction which includes the effect of asperity adhesion forces using the Maugis-Dugdale model. The model spans the range from nano-scale to micro-scale to macro-scale contacts. Three key dimensionless parameters have been identified which represent combinations of surface roughness measures, Burgers vector length, surface energy, and elastic properties. Results are given for the friction coefficient versus normal force, the normal and friction forces versus separation, and the pull-off force for various values of these key parameters.

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21

Jonáš, Alexandr, Martin Kochanczyk, Alexandro D. Ramirez, Michael Speidel, and Ernst-Ludwig Florin. "Mechanical Contact Spectroscopy: Characterizing Nanoscale Adhesive Contacts via Thermal Forces." Langmuir 35, no. 17 (April 9, 2019): 5809–20. http://dx.doi.org/10.1021/acs.langmuir.8b04074.

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22

Spiller, Mark, and Dirk Söffker. "Stator-Rotor Contact Force Estimation of Rotating Machine." Automation 2, no. 3 (June 24, 2021): 83–97. http://dx.doi.org/10.3390/automation2030005.

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In turbomachines, dry friction resulting from stator–rotor contacts is a severe problem that may degrade lifetime of the machine or even lead to complete failure. Knowledge about the system states and contact forces is beneficial for system monitoring or to prevent contacts through, e.g., active magnetic bearings. In this paper, a nonlinear model is derived that describes the lateral rotor vibrations in the case of contact and no contact. The elastic behavior of the shaft is modeled based on the finite-element method. The contact is described by a dry friction model. An augmented system description is formulated that allows estimation of rotor displacements and contact forces by means of nonlinear filtering approaches like an extended Kalman filter. A simulation study was conducted that explicitly considered the hazardous backward whirl. The suggested approach shows suitable estimation performance related to both state and contact force estimation.

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23

Li, B., and S. N. Melkote. "An Elastic Contact Model for the Prediction of Workpiece-Fixture Contact Forces in Clamping." Journal of Manufacturing Science and Engineering 121, no. 3 (August 1, 1999): 485–93. http://dx.doi.org/10.1115/1.2832707.

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The design and evaluation of machining fixture performance requires accurate knowledge of workpiece-fixture contact forces since they strongly impact workpiece accuracy during clamping and machining. This paper presents an elastic contact model for the prediction of workpiece-fixture contact forces due to clamping. The fixture and workpiece are considered to be elastic bodies in the vicinity of the contact region. The model is formulated as a constrained quadratic program by applying the principle of minimum total complementary energy. The model predicts the normal force, and the magnitude and direction of the tangential (friction) force at each workpiece-fixture contact due to clamping forces. Experimental verification of the model under different clamping loads shows good agreement between predicted and measured normal and tangential contact forces. The model can be used to analyze fixture performance in terms of the contact forces and contact region deformation.

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24

Schmidt, Megan M., Mark A. Benscoter, and Paul A. Iaizzo. "Contact Forces Required to Record Monophasic Action Potentials: A Complement to Catheter Contact Force Measurement." IEEE Transactions on Biomedical Engineering 66, no. 10 (October 2019): 2974–78. http://dx.doi.org/10.1109/tbme.2019.2899554.

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25

Nikas, George K. "Particle extrusion in elastohydrodynamic line contacts: Dynamic forces and energy consumption." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, no. 10 (February 16, 2017): 1320–40. http://dx.doi.org/10.1177/1350650117693175.

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The author’s model of particle entrapment and thermoviscoplastic indentation built and experimentally validated in recent publications is utilised to calculate the contact forces on ductile, isolated interference particles passing through elastohydrodynamic, rolling–sliding, line contacts. The model is detailed and enriched by supplementary equations. A parametric study deals with the effects of particle size and cold hardness, kinetic friction coefficient, rolling velocity and slide-to-roll ratio of the contact on the particle contact forces, mean friction coefficient, temperature, plastic work and power required to deform a particle, as well as on dent volume and plastic strain rates of the indented contact surfaces. A factual selection of optimal conditions and parameter values that minimise the disruption of a contaminated contact is thus greatly facilitated.

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26

Goloshchapov, Nikolay. "Solutions of the Problems of a Viscoelastic Dynamic Contact between Smooth Curvilinear Surfaces of two Solid Bodies by the Application of the “Method of the Specific Forces”." Mechanical Engineering Research 5, no. 2 (November 4, 2015): 59. http://dx.doi.org/10.5539/mer.v5n2p59.

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<p class="1Body">Solutions of the problems of a viscoelastic dynamic contact between smooth curvilinear surfaces<strong> </strong>of two solid bodies by the application of the “Method of the specific forces” have been given in the article, and the new conception for the definition of the elastic and the viscous forces in the common case of dynamics of a viscoelastic contact is proposed here by the further development of this method. Essence of this method is that, the forces of viscosity and the forces of elasticity can be found by integration of the specific forces acting inside an elementary volume of the contact zone. It is shown here, that this method allows finding the viscoelastic forces for any theoretical or experimental dependencies between the distance of mutual approach of two solid bodies and the diameter of the contact area. Also, the derivation of the integral equations of the viscoelastic forces, the equations for pressure in the contact is presented. Viscoelastic dynamic contacts between two spherical bodies, and between a spherical solid body and a semi-space at impact have been examined. Work and Energy in the phases of compression and restitution, and at the rolling shear have been derived. Approximate solutions for the differential equations of movement (displacement) by using the method of equivalent work have been derived. Equations for the normal contact stresses have been obtained. Also, equations for kinematic and dynamic parameters of the viscoelastic collision have been derived in this article. Examples of the comparison of theoretical results and conclusions have been given in the paper.</p>

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27

IWNICKI, S. "Simulation of wheel–rail contact forces." Fatigue & Fracture of Engineering Materials & Structures 26, no. 10 (October 2003): 887–900. http://dx.doi.org/10.1046/j.1460-2695.2003.00699.x.

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28

Tang, Tian, Chung-Yuen Hui, and Anand Jagota. "Adhesive contact driven by electrostatic forces." Journal of Applied Physics 99, no. 5 (March 2006): 054906. http://dx.doi.org/10.1063/1.2178854.

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29

Boyd, Stephen P., and Ben Wegbreit. "Fast Computation of Optimal Contact Forces." IEEE Transactions on Robotics 23, no. 6 (December 2007): 1117–32. http://dx.doi.org/10.1109/tro.2007.910774.

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30

McGeer, Tad, and Leigh Hunt Palmer. "Wobbling, toppling, and forces of contact." American Journal of Physics 57, no. 12 (December 1989): 1089–98. http://dx.doi.org/10.1119/1.15795.

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31

Zheng, Q. J., Z. Y. Zhou, and A. B. Yu. "Contact forces between viscoelastic ellipsoidal particles." Powder Technology 248 (November 2013): 25–33. http://dx.doi.org/10.1016/j.powtec.2013.03.020.

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32

Sun, Jing, Nelson Lam, Lihai Zhang, Dong Ruan, and Emad Gad. "Contact forces generated by hailstone impact." International Journal of Impact Engineering 84 (October 2015): 145–58. http://dx.doi.org/10.1016/j.ijimpeng.2015.05.015.

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33

Sun, Jing, Nelson Lam, Lihai Zhang, Emad Gad, and Dong Ruan. "Contact forces generated by fallen debris." Structural Engineering and Mechanics 50, no. 5 (June 10, 2014): 589–603. http://dx.doi.org/10.12989/sem.2014.50.5.589.

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34

Radjai, Farhang, Stéphane Roux, and Jean Jacques Moreau. "Contact forces in a granular packing." Chaos: An Interdisciplinary Journal of Nonlinear Science 9, no. 3 (September 1999): 544–50. http://dx.doi.org/10.1063/1.166428.

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35

Bergmann, G., F. Graichen, and A. Rohlmann. "Hip joint contact forces during stumbling." Langenbeck's Archives of Surgery 389, no. 1 (February 1, 2004): 53–59. http://dx.doi.org/10.1007/s00423-003-0434-y.

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36

Buskermolen, Antonetta B. C., Hamsini Suresh, Siamak S. Shishvan, Andrea Vigliotti, Antonio DeSimone, Nicholas A. Kurniawan, Carlijn V. C. Bouten, and Vikram S. Deshpande. "Entropic Forces Drive Cellular Contact Guidance." Biophysical Journal 116, no. 10 (May 2019): 1994–2008. http://dx.doi.org/10.1016/j.bpj.2019.04.003.

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37

Gnanavel, B. K., and N. S. Parthasarathy. "Effect of interfacial contact forces in radial contact wire strand." Archive of Applied Mechanics 81, no. 3 (February 12, 2010): 303–17. http://dx.doi.org/10.1007/s00419-010-0406-y.

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38

Tong, Ruiting, Zefen Quan, Qi Wan, Xiaojun Fu, and Geng Liu. "A new impact dynamics model of a clearance joint considering the adhesive effects in space environment." MATEC Web of Conferences 306 (2020): 01005. http://dx.doi.org/10.1051/matecconf/202030601005.

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In space environment, there is severe adhesive effect, and the impact contact process shows different phenomenon due to the adhesive forces. In this paper, a new impact dynamics model of a clearance joint is developed considering the adhesive effects. The Hertz contact model, L-J potential and Dugdale model are combined, and an adhesive force term is included in the original hybrid contact force model. Taking a clearance joint as an example, the theory of adhesive forces during the impact contact process is given, and the influence of the adhesive forces is investigated. Negative forces are discovered at the beginning of the contact, and the contact forces of the modified model are higher than the hybrid model. Besides, the indentation depth is also higher than the hybrid model. The energy conservation principle is employed to explain the phenomena, and the contact forces will be underestimated if the adhesive effects are ignored. This work could be contributed to estimating the contact forces and friction forces more reasonablely in the space environment.

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39

Dhaher, Yasin Y., and Leonard E. Kahn. "The Effect of Vastus Medialis Forces on Patello-femoral Contact: A Model-based Study." Journal of Biomechanical Engineering 124, no. 6 (December 1, 2002): 758–67. http://dx.doi.org/10.1115/1.1516196.

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A mathematical model of the patello-femoral joint was introduced to investigate the impact of the vastus medialis (longus, obliquus) forces on the lateral contact force levels. In the model, the quadriceps were represented as five separate forces: vastus lateralis, vastus intermedius, rectus femoris, vastus medialis longus (VML), and obliquus (VMO). By varying the relative force generation ratios of the quadriceps heads, the patello-femoral contact forces were estimated. We sought to analytically determine the range of forces in the VMO and VML that cause a reduction or an increase of lateral contact forces, often the cause of patello-femoral pain. Our results indicated that increased contact forces are more dependent on combinations of muscle forces than solely VMO weakness. Moreover, our simulation data showed that the contact force levels are also highly dependent on the knee flexion angle. These findings suggest that training targeted to reduce contact forces through certain joint angles could actually result in a significant increase of the contact forces through other joint angles.

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40

Tutuncu, Azra N., and Mukul M. Sharma. "The influence of fluids on grain contact stiffness and frame moduli in sedimentary rocks." GEOPHYSICS 57, no. 12 (December 1992): 1571–82. http://dx.doi.org/10.1190/1.1443225.

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The frame moduli of sedimentary rocks are strongly influenced by the properties of the grain contacts. A modified Hertz contact theory is presented for the self consistent calculation of deformation, equilibrium separation distance (film thickness), and contact area of deformation for two spherical asperities in contact and subjected to an external load. We show that surface forces, i.e., electrostatic repulsion, Born, structural, and Van der Waals forces can be incorporated into the contact deformation problem. From the results presented, it is evident that surface forces play an important role in determining seismic wave velocities and attenuations at low confining stresses. The velocities and attenuations computed from the model are compared with measured values for glass beads, Navajo, Berea, Obernkirchner, and Fort Union sandstones. The velocities and attenuations calculated as functions of stress, frequency, fluid type, and saturation are in good agreement with reported experimental data.

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41

Goonetilleke, Ravindra S., and Timothy J. Eng. "Contact Area Effects on Discomfort." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 38, no. 10 (October 1994): 688–90. http://dx.doi.org/10.1177/154193129403801032.

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Most “ergonomic” products attempt to adopt a uniform force distribution strategy to improve comfort. The rationale being that force distribution over a large area reduces pressure and thereby enhances user comfort. However, sensory literature alludes to the concept of spatial summation, i.e. greater sensation by stimulating a larger surface area. Hence spatial summation would tend to suggest a greater discomfort when forces are applied over large surface areas. This study reports the effect of surface area on maximum discomfort causing pressure or maximum pressure tolerance (MPT). Two circular probes of different cross sectional area were used to stimulate the skin surface. The mean MPT with a probe of 5mm diameter was 3.3 times higher than the MPT with a probe of 13mm diameter. These findings suggest the following: • Perceived discomfort and contact area seem to have a “U-relationship” above a critical force value. Traditional thinking of distributing forces is successful only in the first half of the U-curve or with forces below the critical value. The section with the monotonically increasing relationship between discomfort and contact area (i.e., second half of U) may not be seen at very low forces or forces below the critical value. • “High” pressures in concentrated areas may cause less discomfort than “moderate” pressures over a larger area. • The critical or threshold pressure to induce discomfort is force and contact area dependent.

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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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Shripad, Kumar Milind Rewanand, Sriram Sundar, and Saurabh Sanjayrao Suryawanshi. "Development of experimental Vibro-acoustic transfer function for a system with impact." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no. 7 (February 1, 2023): 803–8. http://dx.doi.org/10.3397/in_2022_0113.

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Systems with combined sliding-rolling contacts such as cam-follower, clutches, and gearbox are prone to have clearance(s) as per the design and/or due to manufacturing imperfections or wearing as a result of sliding between components. This clearance non-linearity results in an impact between components, which in turn generates a significant rattle during operation. The noise generation mechanism in rattle is a strong function of impact-velocity and contact forces. The objective of this study is to develop an experimental transfer function to quantify the vibro-acoustics of a cam-follower system with clearance non-linearity. Contact between the cam and the follower is lubricated to minimize the sound generated due to friction. Follower acceleration, reaction forces, and acoustic pressure are measured on a cam-follower setup with combined rolling-sliding contact during impacts under various conditions. Velocity and contact forces are back-calculated using measured signals and the analytical model dynamics. Transfer functions relating the acoustic pressure to velocity and contact forces are estimated in the frequency domain. These transfer functions provide insights into the vibro-acoustic system and can be directly used in conjunction with dynamics models. The output of the study can be used in designing quieter systems with impact.

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Wei, Chin-Chung, and Wen-Hsien Kao. "Analyses of contact forces and kinetic motion on heavy load ball-screw." MATEC Web of Conferences 185 (2018): 00014. http://dx.doi.org/10.1051/matecconf/201818500014.

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Effects of contact angle and groove factor of a heavy load ball-screw are discussed with the variation of contact forces at eight ball circulations. Contact forces are varying as a sinusoidal function of each circulation owing to the variation of phase angle. With the increase of contact angles, contact forces at each ball circulation are decreased and variation in each ball circulation. The decrease of the contact forces means that the contact stresses of contact areas are reduced. Fatigue life of raceways can thus be extended. Low groove factor can reduce skidding speed and friction coefficient. By the analyzing results, optimal transmission performance can be achieved in a heavy-loaded ball-screw.

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Andrews, J. G., and C. K. Cheng. "The Joint Distribution Problem With Multiple Articular Contact Forces." Journal of Biomechanical Engineering 112, no. 3 (August 1, 1990): 364–66. http://dx.doi.org/10.1115/1.2891197.

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The single joint distribution problem with two or more unknown bony contact forces is considered, and an optimal solution procedure free of ad hoc assumptions is described. If two bony contact forces are present, a strictly muscle force dependent equality constraint exists that allows for initial independent estimation of muscle forces, followed by unique estimation of all bony contact force components perpendicular to the straight line connecting their known points of application. However, if three or more bony contact forces are present, no strictly muscle force dependent equality constraint exists, solution separability is lost, and optimal muscle and bony contact forces are obtained simultaneously.

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Williams, John M., Taejoon Han, and Thomas P. Beebe. "Determination of Single-Bond Forces from Contact Force Variances in Atomic Force Microscopy." Langmuir 12, no. 5 (January 1996): 1291–95. http://dx.doi.org/10.1021/la950500j.

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Dao, Tien Tuan, and Philippe Pouletaut. "A Hertzian Integrated Contact Model of the Total Knee Replacement Implant for the Estimation of Joint Contact Forces." Journal of Computational Medicine 2015 (October 13, 2015): 1–9. http://dx.doi.org/10.1155/2015/945379.

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The prediction of lower limb muscle and contact forces may provide useful knowledge to assist the clinicians in the diagnosis as well as in the development of appropriate treatment for musculoskeletal disorders. Research studies have commonly estimated joint contact forces using model-based muscle force estimation due to the lack of a reliable contact model and material properties. The objective of this present study was to develop a Hertzian integrated contact model. Then, in vivo elastic properties of the Total Knee Replacement (TKR) implant were identified using in vivo contact forces leading to providing reliable material properties for modeling purposes. First, a patient specific rigid musculoskeletal model was built. Second, a STL-based implant model was designed to compute the contact area evolutions during gait motions. Finally, a Hertzian integrated contact model was defined for the in vivo identification of elastic properties (Young’s modulus and Poisson coefficient) of the instrumented TKR implant. Our study showed a potential use of a new approach to predict the contact forces without knowledge of muscle forces. Thus, the outcomes may lead to accurate and reliable prediction of human joint contact forces for new case study.

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Wang, Gang, and Zhaohui Qi. "Approximate determination of the joint reaction forces in the drive system with double universal joints." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 7 (April 4, 2017): 1191–207. http://dx.doi.org/10.1177/0954406217702681.

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In this study, a drive system connected by rolling bearings and double universal joints is modeled as a closed-loop multibody system. Because of the existence of redundant constraints, the joint reaction forces cannot be determined uniquely through dynamic analysis. Based on the physical mechanism where the joint reaction forces are the resultants of contact forces at the joint definition point, a methodology of frictionless contact analysis is presented to identify joint reaction forces. In terms of D’Alembert’s principle, the dynamic equations of constrained multibody systems are equivalent to the equilibrium equations of all bodies composed of joint contact forces, externally applied forces, and inertial forces. The equivalent equilibrium equations provide a set of complementary equations to identify the contact positions and contact forces in the rolling bearings and double universal joints. The drive system is also simulated using ADAMS software, where all the joints are released and the corresponding constraint functions are replaced by the impact forces between the joint components. Some conclusions are obtained through the comparison of numerical examples between the proposed method and the ADAMS model. In the double universal joints, the equations are adequate and independent, which results in that the corresponding contact positions and contact forces can be solved uniquely. Then, the correlation between the data produced by these two models is acceptable in the engineering practices. Furthermore, contact details in the double universal joints can be obtained without the calculation of the relative motion between the cross-pin and yokes. However, the reaction forces in the rolling bearings are indeterminate due to that their complementary equations are not independent. The proposed method has high efficiency and acceptable precision.

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Li, Yumeng, He Wang, and Kathy J. Simpson. "Chronic Ankle Instability Does Not Influence Tibiofemoral Contact Forces during Drop Landings." Proceedings 49, no. 1 (June 15, 2020): 5. http://dx.doi.org/10.3390/proceedings2020049005.

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Chronic ankle instability (CAI) is a very common sequela after ankle sprains. Previous studies observed some knee biomechanical and neuromuscular alterations of CAI that could potentially relate to the knee injury mechanism during landings. However, to our knowledge, no studies have assessed the tibiofemoral contact forces for individuals with CAI. The purpose of the study was to compare the tibiofemoral contact forces of participants with CAI versus controls during landings using a computer-simulated musculoskeletal model. Twenty-one female participants with CAI and 21 pair-matched controls performed a drop landing task on a tilted force plate. A seven-camera motion capture system and two force plates were used to test participants’ lower extremity biomechanics. A musculoskeletal model was used to calculate the tibiofemoral contact forces (femur on tibia). No significant between-group differences were observed for the peak tibiofemoral contact forces (p = 0.25–0.48) during the landing phase based on paired t-tests. The group differences ranged from 0.05 to 0.58 body weight (BW). Most participants demonstrated a posterior force (peak = ~1.1 BW) for most of the landing phase and a medial force (peak = ~0.9 BW) and a large compressive force (peak = ~10 BW) in the landing phase. We conclude that CAI may not be related to the increased tibiofemoral contract forces or knee injury mechanisms during landings on tilted surfaces.

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Gast, R. G., P. S. Els, S. Kok, D. N. Wilke, and T. R. Botha. "Identifiability of Tyre Force Contact Prediction from Deformation Measurements." MATEC Web of Conferences 347 (2021): 00027. http://dx.doi.org/10.1051/matecconf/202134700027.

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The possibility of accurately inferring the external forces applied to a vehicle can directly contribute to better safety systems and thus lowers the chance of injury or loss of life. These external forces are applied to a vehicle through the tyres and are challenging to measure directly. Still, it is possible to measure acceleration, deformation, or strain on the inner surface of a tyre. These measurements are theorized to be strongly linked to the forces produced by the tyre. However, it is still unknown whether or not one can always identify external forces from internal measurements in this way. Research has mainly focused on obtaining estimates of tyre forces rather than establishing to what extent these tyre forces are identifiable. This paper investigates this by conducting a virtual experiment that simulates known external forces applied to the tyre and computes the strains and displacements inside the tyre. A virtual inverse simulation then recovers the external forces from either the deformation or strain computed on the inside of the tyre. The identifiability of the forces recovered by the virtual inverse simulation is investigated by adding artificial measurement noise and initial guess perturbations to quantify the variance in the identified forces.

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