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Huajian Gao - One of the best experts on this subject based on the ideXlab platform.
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effect of shear stress on Adhesive Contact with a generalized maugis dugdale cohesive zone model
Journal of The Mechanics and Physics of Solids, 2021Co-Authors: Bo Peng, Xiqiao Feng, Huajian GaoAbstract:Abstract The interplay between interfacial shear stress and adhesion has been an active but controversial subject of Adhesive Contact mechanics, which is currently plagued by diverse, sometimes contradicting, predictions. Recently, McMeeking et al. showed that a reversible interface slip parameter plays an essential role in determining how interfacial shear stress affects adhesion for a Johnson-Kendall-Roberts (JKR) Contact interface. In this paper, Adhesive Contact between a rigid spherical indenter and an elastic half-space is studied with a generalized Maugis-Dugdale (M-D) model, where a constant frictional shear stress presents in the intimate Contact area while a constant Adhesive stress exists in a cohesive zone near the Contact edge. The model solution predicts that the Contact behavior is governed by a non-dimensional reversible shear index α τ ¯ 2 as well as the Maugis parameter λ . More specifically, it is found that the impact of interfacial shear stress on adhesion is most significant when the model approaches the JKR limit, and it gets less pronounced in the transitional regime and eventually becomes negligible in the Derjaguin-Mulller-Toporov (DMT) limit. Such behavior is in distinct contrast to Johnson's phenomenological solution. Finally, the proposed model is experimentally validated by adhesion tests on Contact interfaces with varying Maugis parameters, where the reversible slip factor is experimentally extracted for the first time.
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Adhesive Contact on power law graded elastic solids the jkr dmt transition using a double hertz model
Journal of The Mechanics and Physics of Solids, 2013Co-Authors: Fan Jin, Xu Guo, Huajian GaoAbstract:Abstract A cohesive zone model of axisymmetric Adhesive Contact between a rigid sphere and a power-law graded elastic half-space is established by extending the double-Hertz model of Greenwood and Johnson (1998) . Closed-form solutions are obtained analytically for the surface stress, deformation fields and equilibrium relations among applied load, indentation depth, inner and outer radii of the cohesive zone, which include the corresponding solutions for homogeneous isotropic materials and the Gibson solid as special cases. These solutions provide a continuous transition between JKR and DMT type Contact models through a generalized Tabor parameter μ . Our analysis reveals that the magnitude of the pull-off force ranges from ( 3 + k ) π R Δ γ / 2 to 2 π R Δ γ , where k , R and Δ γ denote the gradient exponent of the elastic modulus for the half-space, the radius of the sphere and the work of adhesion, respectively. Interestingly, the pull-off force for the Gibson solid is found to be identically equal to 2 π R Δ γ , independent of the corresponding Tabor parameter. The obtained analytical solutions are validated with finite element simulations.
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mechanics of non slipping Adhesive Contact on a power law graded elastic half space
International Journal of Solids and Structures, 2011Co-Authors: Xu Guo, Fan Jin, Huajian GaoAbstract:Abstract In previous work about axisymmetric Adhesive Contact on power-law graded elastic materials, the Contact interface was often assumed to be frictionless, which is, however, not always the case in practical applications. In order to elucidate the effect of friction and the coupling between normal and tangential deformations, in the present paper, the problem of a rigid punch with a parabolic shape in non-slipping Adhesive Contact with a power-law graded half-space is studied analytically via singular integral equation method. A series of closed-form analytical solutions, which include the frictionless and homogeneous solutions as special cases, are obtained. Our results show that, compared with the frictionless case, the interfacial friction tends to reduce the Contact area and the indentation depth during adhesion. The magnitude of the coupling effect depends on both the Poisson ratio and the gradient exponent of the half-space. This effect vanishes for homogeneous incompressible as well as for linearly graded materials but becomes significant for auxetic materials with negative Poisson’s ratio. Furthermore, influence of mode mixity on the Adhesive behavior of power-law graded materials, which was seldom touched in literature, is discussed in details.
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Orientation-dependent adhesion strength of a rigid cylinder in non-slipping Contact with a transversely isotropic half-space
International Journal of Solids and Structures, 2009Co-Authors: Haimin Yao, Pradeep R Guduru, Shaohua Chen, Huajian GaoAbstract:Recently, Chen and Gao [Chen, S., Gao, H., 2007. Bio-inspired mechanics of reversible adhesion: orientation-dependent adhesion strength for non-slipping Adhesive Contact with transversely isotropic elastic materials. J. Mech. Phys. solids 55, 1001-1015] studied the problem of a rigid cylinder in non-slipping Adhesive Contact with a transversely isotropic solid subjected to an inclined pulling force. An implicit assumption made in their study was that the Contact region remains symmetric with respect to the center of the cylinder. This assumption is, however, not self-consistent because the resulting energy release rates at two Contact edges, which are supposed to be identical, actually differ from each other. Here we revisit the original problem of Chen and Gao and derive the correct solution by removing this problematic assumption. The corrected solution provides a proper insight into the concept of orientation-dependent adhesion strength in anisotropic elastic solids. ?? 2008 Elsevier Ltd. All rights reserved.
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Bio-inspired mechanics of reversible adhesion : Orientation-dependent adhesion strength for non-slipping Adhesive Contact with transversely isotropic elastic materials
Journal of The Mechanics and Physics of Solids, 2007Co-Authors: Shaohua Chen, Huajian GaoAbstract:Geckos and many insects have evolved elastically anisotropic Adhesive tissues with hierarchical structures that allow these animals not only to adhere robustly to rough surfaces but also to detach easily upon movement. In order to improve our understanding of the role of elastic anisotropy in reversible adhesion, here we extend the classical JKR model of Adhesive Contact mechanics to anisotropic materials. In particular, we consider the plane strain problem of a rigid cylinder in non-slipping Adhesive Contact with a transversely isotropic elastic half space with the axis of symmetry oriented at an angle inclined to the surface. The cylinder is then subjected to an arbitrarily oriented pulling force. The critical force and Contact width at pull-off are calculated as a function of the pulling angle. The analysis shows that elastic anisotropy leads to an orientation-dependent adhesion strength which can vary strongly with the direction of pulling. This study may suggest possible mechanisms by which reversible adhesion devices can be designed for engineering applications.
Shaohua Chen - One of the best experts on this subject based on the ideXlab platform.
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mechanics of Adhesive Contact on a power law graded elastic half space
Journal of The Mechanics and Physics of Solids, 2009Co-Authors: Shaohua Chen, Peng ZhangAbstract:We consider Adhesive Contact between a rigid sphere of radius R and a graded elastic half-space with Young's modulus varying with depth according to a power law E = E-0(z/c(0))(k) (0 1 and v = 0.5, and the strength limit in which the interfacial stress reaches the theoretical strength of adhesion at pull-off. (C) 2009 Elsevier Ltd. All rights reserved.
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Orientation-dependent adhesion strength of a rigid cylinder in non-slipping Contact with a transversely isotropic half-space
International Journal of Solids and Structures, 2009Co-Authors: Haimin Yao, Pradeep R Guduru, Shaohua Chen, Huajian GaoAbstract:Recently, Chen and Gao [Chen, S., Gao, H., 2007. Bio-inspired mechanics of reversible adhesion: orientation-dependent adhesion strength for non-slipping Adhesive Contact with transversely isotropic elastic materials. J. Mech. Phys. solids 55, 1001-1015] studied the problem of a rigid cylinder in non-slipping Adhesive Contact with a transversely isotropic solid subjected to an inclined pulling force. An implicit assumption made in their study was that the Contact region remains symmetric with respect to the center of the cylinder. This assumption is, however, not self-consistent because the resulting energy release rates at two Contact edges, which are supposed to be identical, actually differ from each other. Here we revisit the original problem of Chen and Gao and derive the correct solution by removing this problematic assumption. The corrected solution provides a proper insight into the concept of orientation-dependent adhesion strength in anisotropic elastic solids. ?? 2008 Elsevier Ltd. All rights reserved.
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Bio-inspired mechanics of reversible adhesion : Orientation-dependent adhesion strength for non-slipping Adhesive Contact with transversely isotropic elastic materials
Journal of The Mechanics and Physics of Solids, 2007Co-Authors: Shaohua Chen, Huajian GaoAbstract:Geckos and many insects have evolved elastically anisotropic Adhesive tissues with hierarchical structures that allow these animals not only to adhere robustly to rough surfaces but also to detach easily upon movement. In order to improve our understanding of the role of elastic anisotropy in reversible adhesion, here we extend the classical JKR model of Adhesive Contact mechanics to anisotropic materials. In particular, we consider the plane strain problem of a rigid cylinder in non-slipping Adhesive Contact with a transversely isotropic elastic half space with the axis of symmetry oriented at an angle inclined to the surface. The cylinder is then subjected to an arbitrarily oriented pulling force. The critical force and Contact width at pull-off are calculated as a function of the pulling angle. The analysis shows that elastic anisotropy leads to an orientation-dependent adhesion strength which can vary strongly with the direction of pulling. This study may suggest possible mechanisms by which reversible adhesion devices can be designed for engineering applications.
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non slipping Adhesive Contact between mismatched elastic spheres a model of adhesion mediated deformation sensor
Journal of The Mechanics and Physics of Solids, 2006Co-Authors: Shaohua Chen, Huajian GaoAbstract:A generalized JKR model is established for non-slipping Adhesive Contact between two dissimilar elastic spheres subjected to a pair of pulling forces and a mismatch strain. We discuss the full elastic solution to the problem as well as the so-called non-oscillatory solution in which tension and shear tractions along the Contact interface is decoupled from each other. The model indicates that the mismatch strain has significant effect on the Contact area and the pull-off process. Under a finite pulling force, a pair of adhering spheres is predicted to break apart spontaneously at a critical mismatch strain. This study suggests an adhesion mediated deformation sensing mechanism by which cells and molecules can detect mechanical signals in the environment via Adhesive interactions.
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non slipping Adhesive Contact of an elastic cylinder on stretched substrates
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2006Co-Authors: Shaohua Chen, Huajian GaoAbstract:The plane strain problem of an elastic cylinder in Adhesive Contact with a stretched substrate is studied via a generalized JKR model taking into account the transmission of both tangential and normal tractions across the Contact interface. The width of the Contact region is determined from the Griffith energy balance near the Contact edge. In the absence of external loading, the tangential traction is found to have a negligible effect on the Contact size. As an external stress is applied to stretch the substrate, the Contact solution exhibits three distinct regimes characterized by two threshold strains: (i) the size of the Contact region is hardly affected by the applied loading when the substrate strain is below the first threshold level; (ii) the Contact size decreases quickly with stretch as the substrate strain increases to between the two threshold levels; (iii) the Contact size approaches zero when the substrate strain exceeds the second threshold level. Interestingly, these results share a number of common features with the experimentally observed cell reorientation on a cyclically stretched substrate. An approximate solution is presented in an appendix to represent the numerical results in closed form.
Xu Guo - One of the best experts on this subject based on the ideXlab platform.
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Adhesive Contact on power law graded elastic solids the jkr dmt transition using a double hertz model
Journal of The Mechanics and Physics of Solids, 2013Co-Authors: Fan Jin, Xu Guo, Huajian GaoAbstract:Abstract A cohesive zone model of axisymmetric Adhesive Contact between a rigid sphere and a power-law graded elastic half-space is established by extending the double-Hertz model of Greenwood and Johnson (1998) . Closed-form solutions are obtained analytically for the surface stress, deformation fields and equilibrium relations among applied load, indentation depth, inner and outer radii of the cohesive zone, which include the corresponding solutions for homogeneous isotropic materials and the Gibson solid as special cases. These solutions provide a continuous transition between JKR and DMT type Contact models through a generalized Tabor parameter μ . Our analysis reveals that the magnitude of the pull-off force ranges from ( 3 + k ) π R Δ γ / 2 to 2 π R Δ γ , where k , R and Δ γ denote the gradient exponent of the elastic modulus for the half-space, the radius of the sphere and the work of adhesion, respectively. Interestingly, the pull-off force for the Gibson solid is found to be identically equal to 2 π R Δ γ , independent of the corresponding Tabor parameter. The obtained analytical solutions are validated with finite element simulations.
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mechanics of non slipping Adhesive Contact on a power law graded elastic half space
International Journal of Solids and Structures, 2011Co-Authors: Xu Guo, Fan Jin, Huajian GaoAbstract:Abstract In previous work about axisymmetric Adhesive Contact on power-law graded elastic materials, the Contact interface was often assumed to be frictionless, which is, however, not always the case in practical applications. In order to elucidate the effect of friction and the coupling between normal and tangential deformations, in the present paper, the problem of a rigid punch with a parabolic shape in non-slipping Adhesive Contact with a power-law graded half-space is studied analytically via singular integral equation method. A series of closed-form analytical solutions, which include the frictionless and homogeneous solutions as special cases, are obtained. Our results show that, compared with the frictionless case, the interfacial friction tends to reduce the Contact area and the indentation depth during adhesion. The magnitude of the coupling effect depends on both the Poisson ratio and the gradient exponent of the half-space. This effect vanishes for homogeneous incompressible as well as for linearly graded materials but becomes significant for auxetic materials with negative Poisson’s ratio. Furthermore, influence of mode mixity on the Adhesive behavior of power-law graded materials, which was seldom touched in literature, is discussed in details.
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non slipping Adhesive Contact of a rigid cylinder on an elastic power law graded half space
International Journal of Solids and Structures, 2010Co-Authors: Fan Jin, Xu GuoAbstract:In this paper, Adhesive Contact of a rigid cylinder on an elastic power-law graded half-space is studied analytically with the theory of weakly singular integral equation and orthogonal polynomial method. Emphasis is placed on the coupling effect between tangential and normal directions which was often neglected in previous works. Our analysis shows that the coupling effect tends to reduce the Contact area in the compressive regime. The effect of bending moment on the adhesion behavior is also examined. Like a pull-off force, there also exists a critical bending moment at which the cylinder can be bended apart from the substrate. However, unlike pull-off force, the critical bending moment is insensitive to the gradient exponent of the graded material.
Fan Jin - One of the best experts on this subject based on the ideXlab platform.
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Adhesive Contact on power law graded elastic solids the jkr dmt transition using a double hertz model
Journal of The Mechanics and Physics of Solids, 2013Co-Authors: Fan Jin, Xu Guo, Huajian GaoAbstract:Abstract A cohesive zone model of axisymmetric Adhesive Contact between a rigid sphere and a power-law graded elastic half-space is established by extending the double-Hertz model of Greenwood and Johnson (1998) . Closed-form solutions are obtained analytically for the surface stress, deformation fields and equilibrium relations among applied load, indentation depth, inner and outer radii of the cohesive zone, which include the corresponding solutions for homogeneous isotropic materials and the Gibson solid as special cases. These solutions provide a continuous transition between JKR and DMT type Contact models through a generalized Tabor parameter μ . Our analysis reveals that the magnitude of the pull-off force ranges from ( 3 + k ) π R Δ γ / 2 to 2 π R Δ γ , where k , R and Δ γ denote the gradient exponent of the elastic modulus for the half-space, the radius of the sphere and the work of adhesion, respectively. Interestingly, the pull-off force for the Gibson solid is found to be identically equal to 2 π R Δ γ , independent of the corresponding Tabor parameter. The obtained analytical solutions are validated with finite element simulations.
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mechanics of non slipping Adhesive Contact on a power law graded elastic half space
International Journal of Solids and Structures, 2011Co-Authors: Xu Guo, Fan Jin, Huajian GaoAbstract:Abstract In previous work about axisymmetric Adhesive Contact on power-law graded elastic materials, the Contact interface was often assumed to be frictionless, which is, however, not always the case in practical applications. In order to elucidate the effect of friction and the coupling between normal and tangential deformations, in the present paper, the problem of a rigid punch with a parabolic shape in non-slipping Adhesive Contact with a power-law graded half-space is studied analytically via singular integral equation method. A series of closed-form analytical solutions, which include the frictionless and homogeneous solutions as special cases, are obtained. Our results show that, compared with the frictionless case, the interfacial friction tends to reduce the Contact area and the indentation depth during adhesion. The magnitude of the coupling effect depends on both the Poisson ratio and the gradient exponent of the half-space. This effect vanishes for homogeneous incompressible as well as for linearly graded materials but becomes significant for auxetic materials with negative Poisson’s ratio. Furthermore, influence of mode mixity on the Adhesive behavior of power-law graded materials, which was seldom touched in literature, is discussed in details.
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non slipping Adhesive Contact of a rigid cylinder on an elastic power law graded half space
International Journal of Solids and Structures, 2010Co-Authors: Fan Jin, Xu GuoAbstract:In this paper, Adhesive Contact of a rigid cylinder on an elastic power-law graded half-space is studied analytically with the theory of weakly singular integral equation and orthogonal polynomial method. Emphasis is placed on the coupling effect between tangential and normal directions which was often neglected in previous works. Our analysis shows that the coupling effect tends to reduce the Contact area in the compressive regime. The effect of bending moment on the adhesion behavior is also examined. Like a pull-off force, there also exists a critical bending moment at which the cylinder can be bended apart from the substrate. However, unlike pull-off force, the critical bending moment is insensitive to the gradient exponent of the graded material.
Chungyuen Hui - One of the best experts on this subject based on the ideXlab platform.
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effects of strain dependent surface stress on the Adhesive Contact of a rigid sphere to a compliant substrate
Soft Matter, 2019Co-Authors: Zezhou Liu, Anand Jagota, Katharine E Jensen, Robert W Style, Eric R Dufresne, Chungyuen HuiAbstract:Recent experiments have reported that the surface stress of soft elastic solids can increase rapidly with surface strain. For example, when a small hard sphere in Adhesive Contact with a soft silicone gel is slowly retracted from its rest position, it was found that the retraction force versus displacement relation cannot be explained either by the Johnson–Kendall–Roberts (JKR) theory or a recent indentation theory based on an isotropic surface stress that is independent of surface strain. In this paper, we address this problem using a finite element method to simulate the retraction process. Our numerical model does not have the restrictions of the aforementioned theories; that is, it can handle large nonlinear elastic deformation as well as a surface-strain-dependent surface stress. Our simulation is in good agreement with experimental force versus displacement data with no fitting parameters. Therefore, our results lend further support to the claim that significant strain-dependent surface stresses can occur in simple soft elastic gels. However, significant challenges remain in the reconciliation of theory and experiments, particularly regarding the geometry of the Contact and substrate deformation.
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large deformation and Adhesive Contact studies of axisymmetric membranes
Langmuir, 2013Co-Authors: Evan J Laprade, Rong Long, Chungyuen Hui, Jonathan T Pham, Jimmy Lawrence, Todd Emrick, Alfred J Crosby, Kenneth R ShullAbstract:A model membrane Contact system consisting of an acrylic copolymer membrane and a PDMS substrate was utilized to evaluate a recently developed nonlinear large-deformation Adhesive Contact analysis. Direct measurements of the local membrane apex strain during nonContact inflation indicated that the neo-Hookean model provides an accurate measure of membrane strain and supports its use as the strain energy function for the analysis. Two membrane Contact geometries, exhibiting significantly different strain distributions during withdrawal, were investigated. The first examines the wet Contact of an air pressurized membrane. The second looks at the dry Contact of a fluid deformed membrane in which a stepper motor controls membrane–substrate separation. A time-dependent modulus emerges from the analysis, with principal tensions obtained from a comparison of predicted and experimental membrane profiles. The applicability of this numerical analysis for determining membrane tension, however, is limited by wrinklin...
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Adhesive Contact between a rippled elastic surface and a rigid spherical indenter from partial to full Contact
Soft Matter, 2011Co-Authors: Congrui Jin, Anand Jagota, Krishnacharya Khare, Shilpi Vajpayee, Shu Yang, Chungyuen HuiAbstract:Surface mechanical properties such as adhesion and friction can be controlled by creating a rippled surface. In this paper, we present numerical and experimental studies on Adhesive Contact between a rippled surface and a rigid spherical indenter. In our numerical method, surface interaction is modeled using Lennard-Jones potential with Derjaguin's approximation. We also carry out a systematic experimental investigation by measuring the adhesion between a spherical glass indenter and rippled polydimethylsiloxane (PDMS) strips with varying amplitudes. With increasing ripple amplitude, our experimental results show a monotonic decrease in pull-off force, transition from full to partial Contact, and pressure-sensitive adhesion. Our numerical simulation captures all the salient features of the experimental results remarkably well.
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large deformation Adhesive Contact mechanics of circular membranes with a flat rigid substrate
Journal of The Mechanics and Physics of Solids, 2010Co-Authors: Rong Long, Kenneth R Shull, Chungyuen HuiAbstract:We study the large deformation mechanics of Contact and adhesion between an inflated hyperelastic membrane and a rigid substrate. The initial configuration of the membrane is flat and circular and is clamped at the edge. Two types of friction conditions between the membrane and the substrate are considered: frictionless and no-slip Contact. We derive an exact expression for the energy release rate in terms of local variables at the Contact edge, thus linking adhesion to the Contact angle. Our model can account for the effects of fluid pressure for experiments performed in solution. We also extend our formulation to include surface tension. Numerical simulations for a neo-Hookean membrane are carried out to study the relation between applied pressure and Contact area.
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Adhesive Contact of cylindrical lens and a flat sheet
Journal of Applied Physics, 1996Co-Authors: Manoj K Chaudhury, Chungyuen Hui, Timothy Weaver, E J KramerAbstract:Methods are developed to estimate the adhesion and surface free energies of compliant materials from the Contact deformations of cylindrical lenses with flat sheets. Some important differences are found between the cylindrical Contact studied here and the widely studied geometry of spherical Contact. For example, while the pull‐off force is completely independent of the elastic constants (K) of the materials for spherical Contacts, the pull‐off force for cylindrical Contact is proportional to K1/3. Furthermore, for cylindrical Contacts the Contact width at separation reaches to a value of 39% of the width (a0) at zero load, whereas the corresponding value is 0.63a0 for spherical Contact. The feasibility of using cylindrical Contacts to estimate the surface and Adhesive energies of polymers was investigated using elastomeric polydimethylsiloxane (PDMS) as a model system. PDMS was used in two ways: (1) unmodified and (2) with its surface hydrolyzed with dilute hydrochloric acid. Significant hysteresis of ad...