Modeling the pull-off force of a mushroom-shaped fibrillar adhesive in dynamic detachment

Fibrillar adhesive, as a novel biomimetic controllable adhesive, holds broad application prospects in the fields of medical devices, aerospace, and robotics. Evaluating the critical detachment force (pull-off force) of such materials, that is, establishing a pull-off force model, is one of the key issues to be addressed in the application process. The experimental results show that preload, dwell time, and retraction velocity are key factors affecting critical detachment force. However, there is no model that can take into account the influence of these three factors. In order to accurately evaluate the adhesion performance of fibrillar adhesive, this study took mushroom- shaped fibrillar adhesive (MFSA) as the object and carried out theoretical and experimental research on the modeling problem of its pull-off force. First, we derived a new pull-off force model based on the Gent & Schultz hypothesis and linear elastic fracture theory. In this model, the relative contact area is introduced to quantify the impact of preload and dwell time on the pull-off force, and the rate-dependent properties of the effective adhesion work are used to describe the impact of retraction velocity on the pull-off force. Then, the validity of the model is experimentally investigated. The experimental results show that this paper' s model can accurately predict the pull-off force of MFSA after parameter identification, thereby verifying the model's effectiveness. Finally, we used the pull-off force model to study the effects of model parameters on pull-off force.