Samenvatting

The European common cuttlefish (Sepia officinalis) makes use of undulatory locomotion through its lateral fins. This type of locomotion shows good potential for application for underwater vehicle thrust because it gives the user advantages like maneuverability, stable station keeping, and energy efficiency. This type of locomotion in the cuttlefish is partly made possible because of the viscoelasticity of the fins. By mimicking the viscoelasticity of the cuttlefish fins into an artificial material the benefits of undulatory movement can be used in robotic application, within the field of soft robotics. In this project a material that possibly can be used for this type of application is found by mimicking the viscoelasticity of the cuttlefish fins. To find this material the viscoelastic properties of the cuttlefish fins have been measured and compared with artificial materials showing the same type of viscoelastic behavior. The material has also been tested on the influence of an aqueous environment to accurately mimic the viscoelasticity and to test its potential for underwater usage. Viscoelasticity of the selected artificial material as well as the cuttlefish fins have been tested through impact indentation. The indentation results were computed with the Peleg model so the model values could be statistically compared across the natural and artificial material. The results show that the cuttlefish fins have a relatively fast relaxation time, and the solidity of the material is close to a liquid. Ecoflex 00-10 has been selected to be tested and compared with the cuttlefish. This material shows good customizability of its viscoelastic properties that can be adjusted to fit the properties of the cuttlefish. The Ecoflex has a very similar relaxation time, however the Ecoflex is slightly more solid compared to the cuttlefish. The exposure to water and salinity does influence the viscoelastic behavior of the Ecoflex making the viscoelastic properties exceed the properties of the cuttlefish. However, the Ecoflex has been created with different ratios and the ratio 1:3 shows no significant difference to the cuttlefish even when exposed to water and salinity. So, it can be concluded that Ecoflex 00-10 with a chemical composition ratio of 1:3 shows very similar viscoelasticity to the cuttlefish’s lateral fins. Recommendations for the future include investigating the viscoelasticity of the cuttlefish with other models and adjusting the chemical composition of the Ecoflex 00-10 further to fit the viscoelasticity of the cuttlefish to the fullest extent.