Competitive peeling of bilayer films on rigid curved substrates

The competitive peeling behavior of bilayer films is a critical factor in transfer printing technologies. In this study, we model a length-mismatched bilayer as a stiffness-heterogeneous film and investigate its peeling behavior on curved substrates using Euler–Bernoulli beam theory and the principle of minimum potential energy. In contrast to flat substrates, curvature-induced pre-stored strain energy leads to a counterintuitive decrease in peak peeling force with increasing stiffness. We derive a critical condition for spontaneous delamination as the film stiffness increases. The effects of substrate curvature and peeling angle on the peeling process are also systematically analyzed. Using the critical peeling force associated with the onset of interfacial damage as a criterion, we further examine the competition between delamination pathways at different interfaces, and evaluate the feasibility of controlling fracture routes through curvature-based modulation of the bilayer structure. Additionally, an analytical criterion is established to delineate the applicability range of this curvature-mediated strategy. The theoretical predictions are validated through both quantitative and qualitative experiments. Overall, this work provides new insights into geometry-guided delamination and offers potential design principles for mechanically tunable transfer printing systems.