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Published in Dag K. Brune, Christer Edling, Occupational Hazards in the Health Professions, 2020
Effects of friction are illustrated in Figure 6 where also the coefficient of friction is defined. The force of resistance due to friction can be calculated using the coefficient of friction and the normal force, i.e., the contact force perpendicular to the contact surface. The coefficient of friction, which can assume values between 0 and 1, tells how smooth and even the surfaces are that slide against each other. Examples of coefficients of friction for some common materials are listed in Table 3.
Gears and Gear Trains
Published in Eric Constans, Karl B. Dyer, Introduction to Mechanism Design, 2018
Another important parameter in choosing a set of gears is the pressure angle. Pressure angles are also standardized, and gears with pressure angles of 14.5° and 20° are easy to find. The other standard pressure angles, 22.5° and 25°, are more rare. Three 10 tooth gears with differing pressure angles are shown in Figure 8.30. The difference is subtle, but the 25° pressure angle gears have thicker teeth at the base and are capable of transmitting heavier loads. The tradeoff is a higher normal force – the component of the contact force that does not transmit torque. Since
An elasto-plastic constitutive model of granular materials based on contact force distribution
Published in Masayuki Hyodo, Hidekazu Murata, Yukio Nakata, Geomechanics and Geotechnics of Particulate Media, 2017
This paper attempts at first to examine the basic elasto-plastic model (Chang & Misra 1990a) through the comparison with DEM (Discrete Element Method) simulations. To simplify the problem, linear contact law is used both in micromechanics model and DEM. In particular, we focus on the evolution of contact normal force distribution, which is related to the contact force chain observed in DEM simulation. Based on this result, we propose an additional micro-mechanism that seems to be lacking in the original model. Finally it is demonstrated that a simple implementation of this new mechanism improves the response drastically.
Computational modeling of child’s swallowing to simulate choking on toys
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2020
Yukihiro Michiwaki, Takahiro Kikuchi, Tetsu Kamiya, Yoshio Toyama, Motoki Inoue, Keigo Hanyuu, Megumi Takai, Seiichi Koshizuka
The contact force comprises vertical force and friction force. In this study, the contact force is applied when the soft tissue organ defined as a hyperelastic body contacts each other, and when the toy defined as a rigid body contacts the wall of the organ. First, the hyperelastic wall arranged by particles is smoothed using meta-ball method (Blinn 1982). Then, the penalty method and the impact base method are applied simultaneously to make the wall difficult to repel.
Influence of the friction modelling decisions on the acceptance of the running behaviour of a friction-damped locomotive
Published in Vehicle System Dynamics, 2023
Pedro Millan, João Pagaimo, Hugo Magalhães, Pedro Antunes, Jorge Ambrósio
When contact between two surfaces is detected contact forces develop. The contact force components are decomposed into normal and friction forces, each requiring specific models, which are applied in contact points in each one of the contacting surfaces.