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Modelling clustering of vertically aligned carbon nanotube arrays.

Schaber CF, Filippov AE, Heinlein T, Schneider JJ, Gorb SN - Interface Focus (2015)

Bottom Line: Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties.To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters.The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

View Article: PubMed Central - PubMed

Affiliation: Functional Morphology and Biomechanics, Zoological Institute , Kiel University , Am Botanischen Garten 1-9, 24118 Kiel , Germany.

ABSTRACT
Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties. Experiments indicated a strong decrease of the friction coefficient from the first to the second sliding cycle in repetitive measurements on the same VACNT spot, but stable values in consecutive cycles. VACNTs form clusters under shear applied during friction tests, and self-organization stabilizes the mechanical properties of the arrays. With increasing load in the range between 300 µN and 4 mN applied normally to the array surface during friction tests the size of the clusters increases, while the coefficient of friction decreases. To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters. We calculate the van der Waals forces between the spherical friction probe and bunches of the arrays using the well-known Morse potential function to predict the number of clusters, their size, instantaneous and mean friction forces and the behaviour of the VACNTs during consecutive sliding cycles and at different normal loads. The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

No MeSH data available.


Related in: MedlinePlus

Modelled friction coefficients in five consecutive sliding cycles on the same array of bunches (small solid symbols) and experimentally determined values (open symbols) exemplary at three different mean normal loads Fn. ξ was 0.61 to best match the experimental data for 278 µN normal load, 0.54 for 880 µN and 0.46 for 3860 µN. The model data overdrawn represent the results of three executions of the code with the same parameters. The differences between the runs are hardly visible.
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RSFS20150026F6: Modelled friction coefficients in five consecutive sliding cycles on the same array of bunches (small solid symbols) and experimentally determined values (open symbols) exemplary at three different mean normal loads Fn. ξ was 0.61 to best match the experimental data for 278 µN normal load, 0.54 for 880 µN and 0.46 for 3860 µN. The model data overdrawn represent the results of three executions of the code with the same parameters. The differences between the runs are hardly visible.

Mentions: To match the model with the empirical results, the factor ξ in the model adapts the strength of interaction between the ball and the bunches after the first sliding cycle at different experimental normal loads. The model well predicts the experimentally obtained friction coefficients and their decrease with consecutive sliding cycles (figure 6). ξ decreases monotonically with increasing mean normal load Fn, from 0.61 at the smallest Fn of 278 µN down to 0.46 at the largest Fn of 3860 µN.Figure 6.


Modelling clustering of vertically aligned carbon nanotube arrays.

Schaber CF, Filippov AE, Heinlein T, Schneider JJ, Gorb SN - Interface Focus (2015)

Modelled friction coefficients in five consecutive sliding cycles on the same array of bunches (small solid symbols) and experimentally determined values (open symbols) exemplary at three different mean normal loads Fn. ξ was 0.61 to best match the experimental data for 278 µN normal load, 0.54 for 880 µN and 0.46 for 3860 µN. The model data overdrawn represent the results of three executions of the code with the same parameters. The differences between the runs are hardly visible.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590422&req=5

RSFS20150026F6: Modelled friction coefficients in five consecutive sliding cycles on the same array of bunches (small solid symbols) and experimentally determined values (open symbols) exemplary at three different mean normal loads Fn. ξ was 0.61 to best match the experimental data for 278 µN normal load, 0.54 for 880 µN and 0.46 for 3860 µN. The model data overdrawn represent the results of three executions of the code with the same parameters. The differences between the runs are hardly visible.
Mentions: To match the model with the empirical results, the factor ξ in the model adapts the strength of interaction between the ball and the bunches after the first sliding cycle at different experimental normal loads. The model well predicts the experimentally obtained friction coefficients and their decrease with consecutive sliding cycles (figure 6). ξ decreases monotonically with increasing mean normal load Fn, from 0.61 at the smallest Fn of 278 µN down to 0.46 at the largest Fn of 3860 µN.Figure 6.

Bottom Line: Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties.To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters.The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

View Article: PubMed Central - PubMed

Affiliation: Functional Morphology and Biomechanics, Zoological Institute , Kiel University , Am Botanischen Garten 1-9, 24118 Kiel , Germany.

ABSTRACT
Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties. Experiments indicated a strong decrease of the friction coefficient from the first to the second sliding cycle in repetitive measurements on the same VACNT spot, but stable values in consecutive cycles. VACNTs form clusters under shear applied during friction tests, and self-organization stabilizes the mechanical properties of the arrays. With increasing load in the range between 300 µN and 4 mN applied normally to the array surface during friction tests the size of the clusters increases, while the coefficient of friction decreases. To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters. We calculate the van der Waals forces between the spherical friction probe and bunches of the arrays using the well-known Morse potential function to predict the number of clusters, their size, instantaneous and mean friction forces and the behaviour of the VACNTs during consecutive sliding cycles and at different normal loads. The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

No MeSH data available.


Related in: MedlinePlus