Component assembly with shape memory polymer fastener for microrobots

Ji Suk Kim, Dae Young Lee, Je Sung Koh, Gwang Pil Jung, Kyu Jin Cho

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Adhesives are generally used for the assembly of microrobots, whereas bolts, screws, or rivets are used for larger robots. Although adhesives are easy to apply, lightweight, and small, they cannot be used for repeated assembly and disassembly of parts. In this paper, we present a novel microfastener composed of a polyurethane-based shape memory polymer (SMP) that is lightweight and small but that is easily detached for disassembly. This was achieved by using the shape recovery and modulus change of the SMP. A sheet of macromolded SMP was laser machined into an I-beam-shaped rivet, and notches were added to the structure to prevent stress concentration. Pull-off tests showed that, as the notch radius increased, the disengagement strength of the rivet fastener decreased and the reusability increased. Through the elastoplastic model, a single SMP rivet was calculated to have maximum disengagement strength of 150 N cm-2 in the elastic range, depending on the notch radius. The fasteners were applied to a jumping microrobot. The legs and body were assembled with ten fasteners, which showed no permanent deformation after impact during jumping movements. The legs were easily replaced with ones of different stiffness by heating the engaged sites to make the fasteners compliant and detachable. The proposed detachable SMP microfasteners are particularly useful for testing the isolated performance of microrobot components to determine the optimal designs for these components.

Original languageEnglish
Article number015011
JournalSmart Materials and Structures
Volume23
Issue number1
DOIs
StatePublished - Jan 2014

Keywords

  • blind rivet
  • microfastener
  • microrobot
  • releasable assembly
  • shape memory polymer fastener

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