Cohesive failure of thin layers of soft model adhesives under tension

Abstract

The cohesive failure of soft adhesives is studied using a yield stress fluid as a model adhesive, which allow to relate the viscoelastic properties of the fluid directly to its adhesive performance. We derive a theoretical expression for the force-distance curve as a function of the yield stress, which describes our experimental results very well. The theoretical prediction is obtained by assuming a circular air-adhesive interface; surprisingly, good agreement between theory and experiment is also obtained when strong fingering instabilities are observed in the experiment. This result is confirmed by the fact that we do not find a significant reduction in the work of adhesion when fingering instabilities are present. In addition, we discuss the morphology of the fingering instabilities.

Numerical simulation of 3D viscoelastic flows with free surfaces

“…Fig. 25 and fingering instabilities can be observed from the very beginning of the stretching, leading to branched structures, as described in [21,2,9]. Clearly, such complex shapes cannot be obtained using Lagrangian models, the mesh distortion would be too large.…”

Slow flows of yield stress fluids: yielding liquids or flowing solids?

“…This led to detailed instability criteria and descriptions and analysis of various trends (Coussot 1999, Fontana et al 2013, Ebrahimi et al 2016. The validation of these conclusions by confrontation with experimental data remains extremely limited, and when this was done a reasonable agreement for the finger size (Lindner et al 2000, Derks et al 2003, Maleki-Jirsaraei et al 2005, but a strong discrepancy was found concerning the instability criterion (Barral et al 2010), suggesting some important effect is missed.…”

Investigation of shear failure mechanisms of pressure‐sensitive adhesives

“…When the nominal shear deformation exceeded 400 lm, some peeling processes are initiated at the rear edge of the contact. The peeling front shows a distinctive fingering pattern, which is reminiscent of Saffman-Taylor instabilities for liquids [16][17][18] or elastic instabilities for soft solids. 19,20 These fingering instabilities of the peel front are then associated with extensive deformation and orientation of the polymer chains in the direction of the motion of the shear device.…”