Effects of Wire Diameter, Actuation Temperature, and Liquid Specific Heat on Maximum Contraction Force of Wet Robotic Actuators

Determining the conditions that cause a wet robotic actuator to exert the greatest force was the goal of this experiment.  The factors that were tested were the diameter of the wire and the temperature and specific heat of the actuation liquid.  These factors were investigated with a three factor design of experiment to determine if the factors were significant in determining how force was exerted by the wet robotic actuator.  A rig was constructed to vertically suspend the wire in a pipe closed at one end and filled with a liquid.  The experiment was conducted by pouring one of three different liquids (water, isopropyl alcohol, and castor oil) at one of three different temperatures into the pipe with a wire of three different diameters suspended within it.  The heated liquid transferred its energy into the wire, causing the wire to contract and exert a force, which was then detected by a force meter.  The analysis showed that the diameter of the wire, the temperature of the actuation liquid, and the interaction between the diameter and the specific heat had a significant effect on the force the wire applied.  When the experiment was completed, it was concluded that the wire with the greatest diameter, the liquid with the lowest specific heat, namely castor oil, and the liquid at the highest initial temperature yielded the highest force.

Research Done By:

Jeff Carothers
Lakeview High School

Matt Hoffman
Cousino High School