A relationship between effective work of adhesion and peel force for thin hyperelastic films undergoing large deformation

AbstractRecently, Dalvi and co-authors have shown detailed experimental data of adhesion of soft spheres with rough substrates with roughness measured down to almost the atomic scale, finding that the Persson and Tosatti theory gave satisfactory predictions of the apparent work of adhesion during loading, once the increase of the surface area due to roughness is correctly computed at extremely small scales. We show that unloading data would show similar correlation with the Persson–Tosatti’s simple criterion, but for a much larger effective work of adhesion, which therefore becomes not an “intrinsic” property. This suggests either strong hysteresis even at apparently very low peeling velocities or the need to use a criterion that has different behavior during loading and unloading. We attempt this inspired by the results of Guduru for a simple case of axisymmetric waviness, and a much better fit of the experimental data by Dalvi and co-authors is obtained using the entire set of data at loading and unloading, even assuming a single work of adhesion value. However, we cannot rule out that both (viscoelastic) and (roughness-induced) enhancement effects coexist in these data.

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Direct Extraction of Work of Adhesion from Contact Experiments: Generalization of JKR Theory to Flexible Structures and Large Deformation

The Journal of Adhesion ◽

10.1080/00218464.2011.611090 ◽

2012 ◽

Vol 88 (1) ◽

pp. 70-85 ◽

Cited By ~ 3

Author(s):

Chung-Yuen Hui ◽

Rong Long

Keyword(s):

Large Deformation ◽

Flexible Structures ◽

Work Of Adhesion ◽

Direct Extraction ◽

Jkr Theory ◽

Contact Experiments

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A Numerical Study on Roughness-Induced Adhesion Enhancement in a Sphere with an Axisymmetric Sinusoidal Waviness Using Lennard–Jones Interaction Law

Lubricants ◽

10.3390/lubricants8090090 ◽

2020 ◽

Vol 8 (9) ◽

pp. 90 ◽

Cited By ~ 1

Author(s):

Antonio Papangelo ◽

Michele Ciavarella

Keyword(s):

Numerical Study ◽

Work Of Adhesion ◽

Real Contact Area ◽

Enhancement Effect ◽

Effective Work ◽

Random Roughness ◽

Lennard Jones ◽

Single Scale ◽

Interaction Law ◽

Scale Roughness

Usually, roughness destroys adhesion and this is one of the reasons why the “adhesion paradox”, i.e., a “sticky Universe”, is not real. However, at least with some special type of roughness, there is even the case of adhesion enhancement, as it was shown clearly by Guduru, who considered the contact between a sphere and a wavy axisymmetric single scale roughness, in the limit of short-range adhesion (JKR limit). Here, the Guduru’s problem is numerically solved by using the Boundary Element Method (BEM) with Lennard–Jones interaction law, which allowed us to explore the contact solution from the rigid to the JKR limit. It is shown that adhesion enhancement stops either for low Tabor parameter, or by large waviness amplitudes, due to the appearance of internal cracks within the contact patch. We do not seem to find a clear threshold for “stickiness” (complete elimination of adhesion), contrary to other recent theories on random roughness. The enhancement effect is well captured by an equation in terms of the Johnson parameter derived by Ciavarella–Kesari–Lew, and is much larger than the Persson–Tosatti enhancement in terms of increase of real contact area due to roughness. The Persson–Tosatti energetic argument for adhesion reduction seems to give a lower bound to the effective work of adhesion.

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Peeling of an Extensible Soft Microbeam to Solid: Large Deformation Analysis

International Journal of Applied Mechanics ◽

10.1142/s1758825118500655 ◽

2018 ◽

Vol 10 (06) ◽

pp. 1850065 ◽

Cited By ~ 2

Author(s):

Yulong Gong ◽

Shanpeng Li ◽

Jianlin Liu

Keyword(s):

Large Deformation ◽

Transversality Condition ◽

Energy Functional ◽

Work Of Adhesion ◽

Segment Length ◽

Deformation Analysis ◽

Deformation Model ◽

Maximum Displacement ◽

Concentrated Force ◽

Length Increment

Adhesion and peeling of slender structures at micro and nanoscale have attracted great attention of scientists and engineers, which hold great implications in a number of domains. In this study, we present the model formulation on the peeling of a soft beam under a concentrated force, by considering its large deformation and axis extensibility. The governing equation group and the transversality condition are then derived, according to the variation on the energy functional with movable boundary conditions. We find that the key parameters in peeling, such as the adhered segment length, applied force and length increment of the beam, are correlated with two dimensionless variables, i.e., the non-dimensional maximum displacement of the beam and non-dimensional work of adhesion. The calculated results are in excellent agreement with the experimental data, which are also compared with the infinitesimal deformation model and large deformation model with inextensible axis. These findings shed light on the design of elementary structures in micro and nanodevices, fabrication of nanofiber materials, and better application of micro/nanoprinting technique, etc.

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Mode-mixity-dependent adhesive contact of a sphere on a plane surface

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2009.0461 ◽

2009 ◽

Vol 466 (2117) ◽

pp. 1303-1325 ◽

Cited By ~ 48

Author(s):

Julie F. Waters ◽

Pradeep R. Guduru

Keyword(s):

Contact Area ◽

Phenomenological Model ◽

Plane Surface ◽

Strong Dependence ◽

Contact Problems ◽

Work Of Adhesion ◽

Rigid Sphere ◽

Mode Mixity ◽

Normal Loading ◽

Effective Work

Tangential loading in the presence of adhesion is highly relevant to biological locomotion, but mixed-mode contact of biological materials or similar soft elastomers remains to be well understood. To better capture the effects of dissipation in such contact problems owing to viscoelasticity or irreversible interfacial adhesive processes, a model is developed for the combined adhesive and tangential loading of a rigid sphere on a flat half-space which incorporates a phenomenological model of energy dissipation in the form of increased effective work of adhesion with increasing degree of mode mixity. To verify the model, contact experiments are performed on polydimethylsiloxane (PDMS) samples using a custom-built microtribometer. Measurements of contact area during mixed normal/tangential loading indicate that the strong dependence of the effective work of adhesion upon mode mixity can be captured effectively by the phenomenological model in the regime where the contact area stayed circular and the slip was negligible. Rate effects were seen to be described by a power-law dependence upon the crack front velocity, similar to observations of rate-dependent contact seen for pure normal loading.

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Review of Designing Effective Work Groups.

Contemporary Psychology ◽

10.1037/027954 ◽

1989 ◽

Vol 34 (4) ◽

pp. 409-409

Author(s):

No authorship indicated

Keyword(s):

Work Groups ◽

Effective Work

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Formation of conditions of functioning of management companies of reclamation parks providing highly competitive economic efficiency

Melioration and Water Management ◽

10.32962/0235-2524-2019-6-30-36 ◽

2020 ◽

pp. 30-36

Author(s):

Ivan Abramenko ◽

Svetlana Manzhina ◽

Svetlana Kupriyanova

Keyword(s):

Russian Federation ◽

Rapid Development ◽

Import Substitution ◽

Industrial Sector ◽

Federal Programs ◽

Effective Work ◽

Industrial Parks ◽

Level Of Activity ◽

Decision Making Processes ◽

The Russian Federation

The aim of the study is to find solutions aimed at the formation of optimal conditions for the creation and functioning of reclamation parks on the territory of existing institutions for reclamation subordinated to the Ministry of agriculture of Russia, through the establishment and justification of the necessary list of functions and powers of their management companies. The comparative analysis of the concept of creation of agricultural parks and the documents regulating functioning of agro-industrial parks is carried out. In addition, the studies were conducted in the context of Federal programs and other legislative acts of the Russian Federation. The analysis of regulatory documentation and scientific developments in the field of agro-industrial sector allowed to compare and make informed decisions on the formation of functions and powers of the management companies of reclamation parks. The formed materials will allow to organize highly effective work of the management companies of recreational parks, by endowing the latter with the necessary functions and powers, without burdening them with unnecessary functions that are not within their competence. Thus formation of functions and powers providing competitive level of activity of reclamation parks needs to be carried out on the basis of functions and powers of the industrial and agroindustrial parks regulated by the current legislation. The formed substantiations will allow to accelerate decision-making processes in the field of powers and functions of managing companies of reclamation parks by legislative and Executive authorities, and thus will contribute to more rapid development of the reclamation complex of the Russian Federation, and as a consequence of the implementation of Federal programs and other legislative acts aimed at the development of agriculture and import substitution in this area.

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