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go to next speaker imagePradeep Guduru
Associate Professor, Division of Engineering, Brown University

Pradeep Guduru received Bachelor's degree in Mechanical Engineering from Sri Venkateswara University (Tirupati, India) and Master's degree in Aerospace Engineering from Indian Institute of Science (Bangalore, India). He received his Ph.D. in Aeronautics from California Institute of Technology in 2001. Following graduation, he joined the Division of Engineering at Brown University as a postdoctoral research associate and was appointed as an assistant professor of Engineering in 2002, in the Solid and Structural Mechanics group. His research focus is on experimental mechanics; some of the current problem areas of interest include mechanics of adhesion and friction and electric field induced guided assembly.

Abstract: Mechanics of Biologically Inspired Adhesion, Friction and Engineered Surfaces

Recent discoveries in biological adhesion in animals such as geckos, flies, etc. have inspired attempts to develop practically useful surface engineering technologies to maximize reversible adhesion and frictional properties of a surface. These attempts have opened up a set of contact mechanics problems, the solutions to which can potentially lead to practical benefits. As part of this effort, a theory of wavy surface adhesion and friction has been developed. It is shown that surface waviness causes the detachment process to proceed in alternating stable and unstable segments. Unstable segments dissipate mechanical energy and lead to apparent toughening and strengthening. The instability induced strengthening have the potential to be exploited in designing surface topographies to enhance reversible adhesion of soft materials. The predictions of the theory have been verified experimentally. The work also presents an analysis of the effect of shape of a fiber tip in enhancing adhesion. The second aspect of this work is to create surface micro-architectures and investigate their adhesive and frictional properties. A film terminated tilted fiber architecture has been fabricated and its directional adhesion and sliding resistance behaviors have been investigated. The experiments show that it displays a highly anisotropic sliding resistance. The striking aspect of such a surface architecture is that, at a critical normal force, its sliding resistance in the fiber tilt direction undergoes a dramatic transition, showing a sudden increase in magnitude due to a small drop in the normal tensile force; a response very similar to that of actual gecko feet. Possible mechanisms responsible for such a behavior are discussed.

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