scholarly journals A RIGOROUS MODEL FOR FREQUENCY-DEPENDENT FINGERPAD FRICTION UNDER ELECTROADHESION

2021 ◽  
Vol 19 (1) ◽  
pp. 039
Author(s):  
Fabian Forsbach ◽  
Markus Heß
Keyword(s):  
Frictional Contact ◽  
Macroscopic Model ◽  
Extended Model ◽  
Excitation Voltage ◽  
Frequency Dependent ◽  
Impedance Model ◽  
Wave Forms ◽  
Rigorous Model ◽  
Contact Mechanical ◽  
Relevant Range

In the electroadhesive frictional contact of a sliding fingerpad on a touchscreen, friction is enhanced by an induced electroadhesive force. This force is dominated by the frequency-dependent impedance behavior of the relevant electrical layers. However, many existing models are only valid at frequency extremes and use very simplified contact mechanical approaches. In the present paper, a RC impedance model is adopted to characterize the behavior in the relevant range of frequencies of the AC excitation voltage. It serves as an extension to the macroscopic model for electrovibration recently developed by the authors, which is based on several well-founded approaches from contact mechanics. The predictions of the extended model are compared to recent experimental results and the most influential electrical and mechanical parameters are identified and discussed. Finally, the time responses to different wave forms of the excitation voltage are presented.

Finite elastic wave propagation in rubber

1963 ◽  
Vol 272 (1350) ◽  
pp. 315-330 ◽  
Keyword(s):  
Wave Propagation ◽  
Natural Rubber ◽  
Essential Feature ◽  
Finite Amplitude ◽  
Force Extension ◽  
Synthetic Rubber ◽  
Unloading Wave ◽  
Wave Forms ◽  
Fixed End ◽  
Relevant Range

A detailed experimental study has been made of the free retraction which occurs when one end of a stretched rubber filament is released. The essential feature of the retraction process is the passage of an unloading wave of finite amplitude from the point of release to the fixed end of the filament. Cine films taken at 2500 frames per second showed that for natural rubber the unloading wave proceeded without dispersion at a velocity increasing from about 40 m/s for low extensions to 85 m/s at an extension of 300 %; at higher extensions the unloading wave showed dispersion, the initial stages of unloading proceeding several times more rapidly than the later stages. A hysteretic synthetic rubber (butyl rubber) showed considerable dispersion even for low extensions. An explanation of the observed phenomena is given from which it follows that finite wave-propagation without dispersion is a consequence of the linearity of the force-extension relation in the relevant range of strain. As a test of the theory the technique is modified to demonstrate that (i) unloading waves of different wave forms show no dispersion in natural rubber at extensions up to 250 %. (ii) the predicted dispersion of both stress and strain waves is in agreement with observation, and (iii) the predicted behaviour of a rubber strip on loading by displacing one end at constant velocity is in agreement with observation. A method is proposed for obtaining load-extension relations at high rates of strain using microflash photography.

The Current Sharing Optimization of Paralleled IGBTs in a Power Module Tile Using a PSpice Frequency Dependent Impedance Model

2008 ◽  
Vol 23 (1) ◽  
pp. 206-217 ◽  
Author(s):  
R. Azar ◽  
R. Udrea ◽  
Wai Tung Ng ◽  
F. Dawson ◽  
W. Findlay ◽  
...  
Keyword(s):  
Power Module ◽  
Frequency Dependent ◽  
Impedance Model ◽  
Current Sharing

scholarly journals Frequency dependent impedance model for heteropolar magnetic bearings

2015 ◽  
Vol 39 (8) ◽  
pp. 2119-2130 ◽  
Author(s):  
E.O. Ranft ◽  
G. van Schoor ◽  
C.P. du Rand
Keyword(s):  
Magnetic Bearings ◽  
Frequency Dependent ◽  
Impedance Model

scholarly journals Low Pressure Hysteresis in Materials with Narrow Slit Pores

2018 ◽  
Vol 2 (4) ◽  
pp. 62 ◽  
Author(s):  
Peter Schiller ◽  
Mirco Wahab ◽  
Thomas Bier ◽  
Hans-Jörg Mögel
Keyword(s):  
Vapor Pressure ◽  
Hysteresis Loops ◽  
Low Pressure ◽  
Macroscopic Model ◽  
Hardened Cement ◽  
Narrow Slit ◽  
Extended Model ◽  
Interaction Range ◽  
Relative Vapor Pressure ◽  
Slit Pores

Humidity-dependent closing and reopening slit pores can produce hysteresis loops in sorption diagrams even at low relative vapor pressure. Pore closing is supported by adhesion of the slit wall surfaces. In a macroscopic model for sorption hysteresis in narrow slits, the adhesion energy jumps by a finite value when touching slit walls are separated from each other. We consider a more realistic adhesion model by introducing a smoothly-varying adhesion force, which depends on the distance between the slit walls. The range of the attraction between the slit walls is found to have a pronounced influence on the shape of hysteresis loops at low vapor pressure. A large interaction range avoids an extraordinarily small relative vapor pressure necessary for pore closing, which is a precondition for low pressure hysteresis. Our extended model allows us to describe a discontinuity, which can appear in the desorption branch of swelling/shrinkage diagrams for hardened cement paste.

scholarly journals Voltage-Induced Friction with Application to Electrovibration

Lubricants ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 102 ◽  
Author(s):  
Markus Heß ◽  
Valentin L. Popov
Keyword(s):  
Experimental Data ◽  
Coulomb Friction ◽  
Frictional Contact ◽  
Recent Literature ◽  
Adhesion Force ◽  
Unit Area ◽  
Macroscopic Model ◽  
Experimental Investigations ◽  
Contact Interface ◽  
Frictional Contacts

Due to the growing interest in robotic and haptic applications, voltage-induced friction has rapidly gained in importance in recent years. However, despite extensive experimental investigations, the underlying principles are still not sufficiently understood, which complicates reliable modeling. We present a macroscopic model for solving electroadhesive frictional contacts which exploits the close analogy to classical adhesion theories, like Johnson-Kendall-Roberts (JKR) and Maugis, valid for electrically neutral bodies. For this purpose, we recalculate the adhesion force per unit area and the relative surface energy from electrostatics. Under the assumption of Coulomb friction in the contact interface, a closed form equation for the friction force is derived. As an application, we consider the frictional contact between the fingertip and touchscreen under electrovibration in more detail. The results obtained with the new model agree well with available experimental data of the recent literature. The strengths and limitations of the model are clearly discussed.

Different Forms of Work Satisfaction

1998 ◽  
Vol 3 (3) ◽  
pp. 209-218 ◽  
Author(s):  
André Büssing ◽  
Thomas Bissels
Keyword(s):  
Work Satisfaction ◽  
Preliminary Evidence ◽  
Qualitative Approach ◽  
Extended Model ◽  
Work Situation ◽  
Structured Interviews ◽  
Global Satisfaction ◽  
Evaluative Processes ◽  
The Right ◽  
Level Of Aspiration

The extended model of different forms of work satisfaction ( Büssing, 1991 ), originally proposed by Bruggemann (1974) , is suggested as a distinctive qualitative approach to work satisfaction. Six forms of work satisfaction—progressive, stabilized, resigned satisfaction, constructive, fixated, resigned dissatisfaction—are derived from the constellation of four constituent variables: comparison of the actual work situation and personal aspirations, global satisfaction, changes in level of aspiration, controllability at work. Preliminary evidence from semi-structured interviews with 46 nurses shows that the dynamic model is headed in the right direction (qualitative differentiation of consistently high propertions of satisfied employees, uncovering processes of person-work situation interaction). Qualitative methods demonstrated their usefulness in accessing underlying cognitive and evaluative processes of the forms, which are often neglected by traditional attitude-based satisfaction research.

Mutuality in Acculturation

2013 ◽  
Vol 221 (4) ◽  
pp. 205-213 ◽  
Author(s):  
Gabriel Horenczyk ◽  
Inga Jasinskaja-Lahti ◽  
David L. Sam ◽  
Paul Vedder
Keyword(s):  
Intergroup Relations ◽  
Extended Model ◽  
Psychological Study ◽  
Intergroup Interactions ◽  
Mutual Contact ◽  
Acculturation Model ◽  
Plural Societies ◽  
Perceptions And Expectations

This paper focuses on processes and consequences of intergroup interactions in plural societies, focusing primarily on majority-minority mutuality in acculturation orientations. We examine commonalities and differences among conceptualizations and models addressing issues of mutuality. Our review includes the mutual acculturation model ( Berry, 1997 ), the Interactive Acculturation Model (IAM – Bourhis et al., 1997 ), the Concordance Model of Acculturation (CMA – Piontkowski et al., 2002 ); the Relative Acculturation Extended Model (RAEM – Navas et al., 2005 ), and the work on acculturation discrepancies conducted by Horenczyk (1996 , 2000 ). We also describe a trend toward convergence of acculturation research and the socio-psychological study of intergroup relations addressing issues of mutuality in attitudes, perceptions, and expectations. Our review has the potential to enrich the conceptual and methodological toolbox needed for understanding and investigating acculturation in complex modern societies, where majorities and minorities, immigrants and nationals, are engaged in continuous mutual contact and interaction, affecting each other’s acculturative choices and acculturative expectations.

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