Influence of Antagonistic Tensions on Distributed Friction Forces of Multisegment Tendon-Driven Continuum Manipulators With Irregular Geometry

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

Download Full-text

Faculty Opinions recommendation of Friction forces position the neural anlage.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.727446584.793530415 ◽

2017 ◽

Author(s):

Xavier Trepat

Keyword(s):

Friction Forces

Download Full-text

Slipping–rolling transitions of a body with two contact points

Nonlinear Dynamics ◽

10.1007/s11071-021-06538-5 ◽

2021 ◽

Author(s):

Mate Antali ◽

Gabor Stepan

Keyword(s):

Rigid Body ◽

Contact Point ◽

Static Friction ◽

Rigid Body Dynamics ◽

Contact Forces ◽

Friction Forces ◽

Contact Points ◽

Body Dynamics ◽

Coulomb Model ◽

Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

Download Full-text

Position regulation in Cartesian space of a class of inextensible soft continuum manipulators with pneumatic actuation

Mechatronics ◽

10.1016/j.mechatronics.2021.102573 ◽

2021 ◽

Vol 76 ◽

pp. 102573

Author(s):

Enrico Franco ◽

Arnau Garriga Casanovas ◽

Jacky Tang ◽

Ferdinando Rodriguez y Baena ◽

Alessandro Astolfi

Keyword(s):

Pneumatic Actuation ◽

Cartesian Space ◽

Continuum Manipulators ◽

Position Regulation

Download Full-text

Forward Kinematic Modeling of Conical-Shaped Continuum Manipulators

Robotica ◽

10.1017/s0263574720001484 ◽

2021 ◽

pp. 1-19

Author(s):

A. H. Bouyom Boutchouang ◽

Achille Melingui ◽

J. J. B. Mvogo Ahanda ◽

Othman Lakhal ◽

Frederic Biya Motto ◽

...

Keyword(s):

Neural Networks ◽

Data Collection ◽

Robot Control ◽

Deep Neural Networks ◽

Forward Kinematics ◽

Kinematic Modeling ◽

Experimental Platform ◽

Continuum Manipulators ◽

Forward Kinematic

SUMMARY Forward kinematics is essential in robot control. Its resolution remains a challenge for continuum manipulators because of their inherent flexibility. Learning-based approaches allow obtaining accurate models. However, they suffer from the explosion of the learning database that wears down the manipulator during data collection. This paper proposes an approach that combines the model and learning-based approaches. The learning database is derived from analytical equations to prevent the robot from operating for long periods. The database obtained is handled using Deep Neural Networks (DNNs). The Compact Bionic Handling robot serves as an experimental platform. The comparison with existing approaches gives satisfaction.

Download Full-text

Peristaltic thrusting of a thermal-viscosity nanofluid through a resilient vertical pipe

Zeitschrift für Naturforschung A ◽

10.1515/zna-2020-0054 ◽

2020 ◽

Vol 75 (8) ◽

pp. 727-738 ◽

Cited By ~ 1

Author(s):

Ramzy M. Abumandour ◽

Islam M. Eldesoky ◽

Mohamed H. Kamel ◽

Mohamed M. Ahmed ◽

Sara I. Abdelsalam

Keyword(s):

Pressure Gradient ◽

Hartmann Number ◽

Amplitude Ratio ◽

Variable Viscosity ◽

Friction Forces ◽

Long Wavelength ◽

Viscosity Parameter ◽

Long Wavelength Approximation ◽

Wavelength Approximation ◽

Theoretical Results

AbstractIn the article, the effects of the thermal viscosity and magnetohydrodynamic on the peristalsis of nanofluid are analyzed. The dominant neutralization is deduced through long wavelength approximation. The analytical solution of velocity and temperature is extracted by using steady perturbation. The pressure gradient and friction forces are obtained. Numerical results are calculated and contrasted with the debated theoretical results. These results are calculated for various values of Hartmann number, variable viscosity parameter and amplitude ratio. It is observed that the pressure gradient is reduced with an increase in the thermal viscosity parameter and that the Hartmann number enhances the pressure difference.

Download Full-text

Influence of Nanoscale Textured Surfaces and Subsurface Defects on Friction Behaviors by Molecular Dynamics Simulation

Nanomaterials ◽

10.3390/nano9111617 ◽

2019 ◽

Vol 9 (11) ◽

pp. 1617 ◽

Cited By ~ 1

Author(s):

Ruiting Tong ◽

Zefen Quan ◽

Yangdong Zhao ◽

Bin Han ◽

Geng Liu

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Friction Force ◽

Copper Substrate ◽

Dynamics Simulation ◽

Textured Surfaces ◽

Friction Forces ◽

Subsurface Structures ◽

Texture Orientation ◽

Subsurface Defects

In nanomaterials, the surface or the subsurface structures influence the friction behaviors greatly. In this work, nanoscale friction behaviors between a rigid cylinder tip and a single crystal copper substrate are studied by molecular dynamics simulation. Nanoscale textured surfaces are modeled on the surface of the substrate to represent the surface structures, and the spacings between textures are seen as defects on the surface. Nano-defects are prepared at the subsurface of the substrate. The effects of depth, orientation, width and shape of textured surfaces on the average friction forces are investigated, and the influence of subsurface defects in the substrate is also studied. Compared with the smooth surface, textured surfaces can improve friction behaviors effectively. The textured surfaces with a greater depth or smaller width lead to lower friction forces. The surface with 45° texture orientation produces the lowest average friction force among all the orientations. The influence of the shape is slight, and the v-shape shows a lower average friction force. Besides, the subsurface defects in the substrate make the sliding process unstable and the influence of subsurface defects on friction forces is sensitive to their positions.

Download Full-text