Determination of Toughness Variation and Cohesive Zone Parameters for De-bonding of Adhesively Bonded PMMA and Steel Using the Shaft-loaded Blister Test

In this work, the shaft-loaded blister test (SLBT) is employed to investigate the de-bonding of a poly-metha-methyl-acrylate (PMMA) layer adhesively bonded to a steel layer. During de-bonding, the mode-mixity does not remain constant in this test; hence, the variation of mode-mixity with the change in de-bond size (blister radius) and the out-of-plane displacement of the PMMA layer is established through Finite Element Analysis (FEA). Experiments are performed in which the load, load-point displacement, and de-bond size is recorded synchronously. Three different thicknesses of PMMA layer are considered in experiments. The variation in toughness as a function of mode-mixity is evaluated. FE simulations with embedded cohesive zone model (CZM) are carried out, and the mixed-mode cohesive zone modelling parameters are identified by comparing the numerical results with experimental observations. By using this approach, the toughness variation as a function of mode-mixity and the CZM parameters is determined using the SLBT.