Mr. Wenkun Zhang - M.Sc. Candidate
12/03/2025
ZOOM
12:30 - Jerusalem time / 18:30 - Beijing time
Bio-inspired fibrillar dry adhesives have garnered significant research interest due to their strong yet reversible adhesion. To enhance adhesion performance, extensive efforts have been made to understand the detachment mechanisms of these micro-patterned surfaces.
This study examines a fundamental punch-shaped fibril in contact with a substrate, where the rounded corner at the interface resembles a crack—an effective approximation for common applications. Asymptotic analysis of bi-material systems reveals a stress singularity at this interface, which is considered the primary cause of failure.
Based on this, two theoretical models are developed to characterize adhesive strength depending on the ratio of the initial crack length to the size of the process zone. When the initial crack is significant, the energy release rate model predicts failure when the strain energy release rate reaches a critical threshold, leading to crack propagation. Conversely, when the initial crack is negligible, the cohesive zone model describes failure through maximum separation. Previous studies have explored shape modifications and material property adjustments, such as mushroom-shaped fibrils and gradient-material fibrils, to reduce edge singularity and improve interfacial stress distribution. However, these methods are constrained by manufacturing limitations at small scales.
This study proposes a simpler, manufacturable strategy based on the well-known crack shielding effect, where introducing parallel cracks effectively reduces the interface stress singularity.