CONTRIBUTION TO THE STUDY OF FRICTION PHENOMENA. APPLICATION TO PAPER MATERIALS.
|Start date||08-04-2015 14:00|
|Finish date||08-04-2015 15:00|
|Location||Room 500 - 501, Central Building|
|Speaker's name||Nicolas FULLERINGER|
|Speaker's institute||Univ. Grenoble Alpes/CNRS|
|Contact name||Isabelle COMBE|
|Host name||Alexander RACK|
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The friction of paper materials influences the reliability and efficiency of numerous industrial mechanisms, e.g., the separation of paper materials in printers or automatic teller machines (ATM), the rolling of paper, or the stability of stacks. However, the friction of paper materials remains poorly understood and characterized.
The standard methods for measuring the force of friction between papers appeared limited in terms of repeatability and experimental conditions. Thus, we developed a new method allowing more accurate and repeatable measurements. We also developed a method for high speed (1 m.s-1) measurements.
We then studied the influence of protocol parameters on the paper friction, e.g., sliding velocity, acceleration, direction, and normal load. In particular, the influence of the sliding distance on the force of friction was strong (up to -50% in 50 cm). Therefore, we proposed an extensive characterization of this phenomenon, based on specific experiments and a novel model of friction.
We also studied the influence of temperature and humidity on the friction of paper. Our results suggest that the increase in friction force with humidity is mainly due capillary bridges between the contacting surfaces.
We finally studied the separation of envelopes in franking machines, as it relies on paper friction. We created a model of envelopes stack. This model allowed us to determine the conditions allowing a correct separation of envelopes. We patented a technology to fulfill these conditions.
This seminar introduces the difficulties and questions faced when studying friction. We conclude by suggesting that the characterization of interfaces using synchrotron radiation could allow breakthrough contributions in the study of friction.
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