Mechanics of Peeling: Cohesive Zone Law and Stability

Citation

Kovalchick, Christopher (2011) Mechanics of Peeling: Cohesive Zone Law and Stability. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/W2KT-CY70. https://resolver.caltech.edu/CaltechTHESIS:05262011-172059575

Abstract

The measurement of interface mechanical properties between an adhesive layer and a substrate is significant for optimization of a high-quality interface. A common method for measuring these properties is the peel test. While there are many interesting applications of peel in such areas as cell and gecko adhesion, the focus here is to obtain a better understanding of the fundamental mechanics underlying the problem.

The mechanics of the peel test is examined through experiments, finite element simulations, and theoretical analysis with the aim of developing governing relations to describe the role of fracture in the peel test for elastic adhesive tapes. An inverse formulation is developed to extract a cohesive zone law from a set of experimental peel tests using a theoretical framework based upon non-linear beam theory. Through extracting a cohesive zone law, the adhesion energy during a peel test is determined along with the force distribution in the process zone. This local method of determining the adhesion energy is compared to a global method used by Rivlin in the context of finite deformations, showing good agreement.

The effect of rate-dependency in the peel test is also examined experimentally, with the results used to derive a rate-dependent power-law for the adhesion energy in a peel test as a function of the peel rate. The effects of varying different geometrical parameters during the peel test and how they affect the force distribution and adhesion energy are also presented. Finally, a study of the stability in the peel test, including the role of compliance through several newly developed force-controlled experimental configurations is discussed. The stiffness of the system is varied by altering the magnitude and direction of the applied load during a test. This change in stiffness can be tuned in order to trigger or delay the onset of instability. Theoretical stability criteria are also presented to in order to develop insights of the role of parameters investigated experimentally.

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