Collections > UNC Chapel Hill Undergraduate Honors Theses Collection > Functional Actuation of Mandrel Formed Twisted Coiled Polymer (TCP) Muscles in Organic Temperature Ranges
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Functional Actuation of Mandrel Formed Twisted Coiled Polymer (TCP) Muscles in Organic Temperature Ranges

  • File Type: pdf
  • | Filesize: 1.8 MB
  • Date Deposited: 2018-04-29
  • Date Created: 2018-04-01

Path:  Collections > UNC Chapel Hill Undergraduate Honors Theses Collection > Functional Actuation of Mandrel Formed Twisted Coiled Polymer (TCP) Muscles in Organic Temperature Ranges

Mandrel formed TCP muscles are an existing, but under researched form of thermally actuated artificial muscles, which are made by coiling a highly twisted monofilament plastics such as Nylon 6/6 (sewing thread) helically. An increase in temperature causes the fiber to shrink axially and expand radially. The radial expansion causes fiber untwisting, which compounds in a much larger tensile actuation (TA) and tensile stress (TS). To cause expansions, TCP muscles can also be coiled in the opposite direction of their fiber twist. These heterochiral fibers can be used to counteract length changes of the homochiral muscles caused by ambient temperature changes. Currently, the maximum contraction of 49% for mandrel formed TCP muscles has taken place at a 5.1 spring index and has achieved a 1 MPa stress over a 70K temperature range (25°C to 95°C). Human muscle have an average TS of 0.35 MPa and TA greater than 40%. To make viable TCP muscles to be comparable with human muscle, which have an average TS of 0.35 MPa and TA greater than 40% that actuate over body temperature range of (33.2 °C to 38.2 °C) the contraction must be improved by 1143% and the stress can be reduced by 65%. The main goal of this study was to conduct an isometric test where the muscles are heated from 33.2 °C to 38.2 °C and contract while tensioned by a 1.75g (most likely 2g) weight to determine if the muscle made from 0.25mm diameter monofilament can contract 40% its length while exerting a stress of 0.35 MPa.

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