Many structures in nature that undergo curling deformation engage in dynamic adhesive interactions with the external environment.These dynamic behaviors typically occur in high-viscosity environments,where the dynamic adhesive behavior at interfaces can modulate the bending deformation,reducing its propagation speed and,in some cases,preventing bending deformation.For instance,red blood cells undergo pore formation and exhibit membrane bending during malaria infection.Dynamic adhesion in motion manifests mechanical responses and phenomena that differ from static adhesion.However,traditional adhesion measurements,including peel tests and probe tests,are performed under near-static conditions,and it is challenging to extrapolate them to high-speed scenarios(exceeding 1 m/s).In addition,most models for dynamic bending deformations neglect the influence of adhesive boundaries,failing to describe how adhesive forces from the external environment affect the curling motion.Therefore,studying how a natural bender,under adhesive conditions,can regulate its speed during high-velocity bending is of great interest.To gain a deeper understanding of the mechanics of dynamic adhesion,this paper examines the behavior of a naturally bending body with adjustable speed rolling on a thin-film adhesive substrate.Our research uncovers the correlation between the dynamic adhesive properties of soft materials and the debonding velocity at the leading edge of motion.Firstly,high-speed photography is utilized to experimentally investigate the motion characteristics of samples with varying natural curvatures on the adhesive substrate.Our results demonstrate that a stable and self-similar structure is observed during motion,and the velocity of natural benders on the adhesive substrate is consistently lower than on a non-adhesive substrate.Additionally,we have developed a theoretical analysis using matched asymptotic expansions and self-similar solutions to describe the long-term motion of natural benders.We have established a quantitative relationship between the debonding velocity,the natural curvature of the natural bender,and the adhesive strength of soft materials,enabling control over the motion of natural benders on the adhesive substrate.Combining our model and experiments,we have discovered that the adhesive strength of the substrate decreases with the increase in velocity at the leading edge of motion within the range of our measurements.Further analysis of the leading edge of motion reveals a"stepped"peeling trajectory with reduced velocities,featuring an"energy storage phase"during which the adhesive front remains nearly static,and an"energy release phase"during which fast propagation occurs.Inspired by the design of speed bumps,this paper studies a patterned substrate that combines adhesive and non-adhesive areas.In this study,we developed substrates with a combination of adhesive and non-adhesive characteristics,identifying a critical size for the adhesive portion.We observed that substrates with only partial adhesion can slow down objects as effectively as those completely covered in adhesive.This effectiveness is attributed to the alternating adhesive and non-adhesive areas,which not only multiply the energy storage and dissipation cycles but also increase internal friction within the layers,thereby enhancing kinetic energy dissipation.Furthermore,the frequent transitions between these two substrate types modify the boundary conditions in the self-similar region,resulting in various modifications to the self-similar solution.Our research provides a deeper understanding of the dynamic adhesion properties of soft materials and offers insights for the design of energy-absorbing structures.
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维普
