Modeling and characterization for straight twisted polymer fiber actuators in blocked torsion: Effect of radial thermal expansion

Kentaro Takagi, Hiroki Iwai, Chihaya Oiwa, Toshihira Irisawa, Masatoshi Shioya, Ken Masuya, Kenji Tahara, Daichi Sakurai, Haruhiko Watanabe, Kinji Asaka

Research output: Contribution to journalArticlepeer-review

Abstract

This paper discusses a new model and experimental characterization for thermal responses of straight twisted polymer fiber (TPF) actuators in blocked torsion. The proposed model is derived from combining the fiber stiffness matrix with Shafer's model of free torsion. The derived model predicts that the blocking torque increases as the initial twist increases. Although it is not widely recognized, the tension of a straight TPF decreases as the initial torsion increases, and this paper explains this fact. The proposed model predicts the decrease in tension by using Shafer's kinematic model that considers the effect of radial thermal expansion. Experimental characterization and model verification are performed using nylon 6 (polyamide 6) fiber samples with ten different initial twists, ranging from weak to strong. The results indicate that as the initial twist increases, the torque increases and the tension decreases. The tension fluctuates with respect to time. The experimental results show that the shear modulus increases as the initial twist increases. The predictions of the proposed model are reasonably consistent with the experimental thermal responses of straight TPFs in blocked torsion when the constants obtained by experimental characterization are used.

Original languageEnglish
Article number065023
JournalSmart Materials and Structures
Volume30
Issue number6
DOIs
Publication statusPublished - Jun 2021

All Science Journal Classification (ASJC) codes

  • Signal Processing
  • Civil and Structural Engineering
  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Electrical and Electronic Engineering

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