Application of Active Materials to Aquatic Biomimetics
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Date
1997
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Abstract
In the area of underwater vehicle design, the development of highly maneuverable vehicles is presently of interest with their design being based on the swimming techniques and anatomic structures of fish; primarily the undulatory body motions, the highly controllable fins and the large aspect ratio lunatic tail. The tailoring and implementation of the accumulated knowledge into biomimetic vehicles is a task of multidisciplinary nature with two of the dominant fields being actuation and hydrodynamic control.
This project is the first experimental step towards the development of a type of biomimetic muscle that utilizes Shape Memory Alloy (SMA) technology. The "muscle", which imitates the fish-like movements, is presently applied to the control of hydrodynamic forces and moments, including thrust generation, on a 2-D hydrofoil. The main actuation elements are two sets of thin SMA wires (0.015" to 0.027") embedded into an elastomeric element of the muscle that provides the main structural support. Controlled heating and cooling of the two wire sets generates bidirectional bending of the elastomer, which in tum deflects (for quasi-static control) or oscillates (for thrust generation) the trailing edge of the hydrofoil. The aquatic environment of the hydrofoil lends itself to cooling schemes that utilize the excellent heat transfer properties of water. The modeling of deflected shapes as a function of input current has been carried out by members of Shape Memory Alloy Research Team (SMART) in the department using a thermomechanical constitutive model for SMA coupled with the elastic response of the elastomer. An approximate structural analysis model, as well as detailed FEM analysis has been performed and the model predictions have been compared with preliminary experimental measurements.
Description
Program year: 1996/1997
Digitized from print original stored in HDR
Digitized from print original stored in HDR
Keywords
biomimetic vehicles, hydrodynamic control, actuation, biomimetic muscle