Krupal Patel

Abstract:

In pressure-sensitive adhesive (PSA) tapes, adhesive failure is often accompanied by cavitation and fibrillation. In this paper, we focus specifically on fibrillation. We model the behavior using a single fibril (mono-fibril) configuration with the axisymmetric boundary conditions. Using the finite element method, we simulate the mono-fibril with varying aspect ratios using hyperelastic models such as Arruda–Boyce and Yeoh. First, we explain why the deformation of these fibrils is not purely uniaxial. We then analyze the normalized force–stretch response using appropriate scaling models. Then we examine the impact of changing strain-hardening, inter-fibrillar distance, and bulk modulus on the fibril response. Following this, we investigate fibril debonding using parameters of the Yeoh model fitted to the uniaxial rheological experimental data from two PSA tapes, referred to as PSA types 6A and 6B. Based on this analysis, we derive the power laws for debonding stretch and debonding force for both PSA types. Finally, we compare our findings with experimental data on mono-fibril debonding from the literature.

Abstract:

We present a computationally efficient Python algorithm based on the Boundary Element Method (BEM) for frictionless linear elastic axisymmetric contact of coated solids. The algorithm solves indentation problems using conical, spherical, and cylindrical flat indenters, with results also reported for flat punch indentation on a soft-coated substrate. To validate BEM, we implement Finite Element Method (FEM) simulations, analyzing soft layers with Poisson ratios of 0.25, 0.4, and 0.49, aspect ratios from 0.25 to 10, and modulus mismatches of 10 and 100. BEM and FEM show good agreement for compressible soft layers but diverge as incompressibility increases. For Poisson’s ratio of 0.4999, BEM fails due to confinement effects. We verify FEM results using the Poker-chip test, confirming accuracy in highly confined, nearly incompressible cases. For compressible soft layer and large aspect ratios, we found good agreement between BEM and analytical result of Poker-chip test applicable in that regime.