Characterizing the adhesion between thin films and rigid substrates using DIC-informed inverse finite elements and the blister test

Characterizing the adhesion between thin films and rigid substrates is crucial in engineering applications. Still, existing standard methods suffer from issues such as poor reproducibility, difficulties in quantifying adhesion parameters, or overestimation of adhesion strength and fracture energy. Recent studies have shown that the blister test (BT) is a superior method for characterizing adhesion, as it provides a quantifiable measurement of mix-mode fracture energy, and it is highly reproducible. In this paper, we present a novel method to characterize mechanical mix-mode adhesion between thin films and rigid substrates using the BT. Our method combines the full triaxial displacement field obtained through Digital Image Correlation with inverse Finite Element Method simulations using Cohesive Zone Elements. This approach eliminates the need for making any mechanistic or kinematic assumptions of the blister formation and allows the characterization of the full traction-separation law governing the adhesion between the film and the substrate. To demonstrate the efficacy of this methodology, we conducted a case study analyzing the adhesion mechanics of a polymeric pressure-sensitive adhesive on an aluminum substrate. Our results indicate that the proposed technique is a reliable and effective method for characterizing the mix-mode traction separation law governing the mechanical behavior of the adhesive interface and could have broad applications in the field of materials science and engineering. Also, by providing a comprehensive understanding of the adhesion mechanics between thin films and rigid substrates, our method can aid in the design and optimization of adhesively bonded structures