Modeling of Artificial <i>Aurelia aurita</i> Bell Deformation

Joshi, Keyur; Villanueva, Alex; Smith, Colin; Priya, Shashank

doi:10.4031/mtsj.45.4.13

Cited by 7 publications

(7 citation statements)

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“…Animal propulsive systems can be used to generate thrust or increase drag to orient forces in opposition to currents, wave action, buoyancy changes, and collisions with other bodies. An artificial jellyfish (Figure 4) could hold position and operate in the open ocean over an extended deployment like the real jellyfish, whose swimming motions use minimal energy (Joshi et al, 2011).…”

Section: Figurementioning

confidence: 99%

Advantages of Natural Propulsive Systems

Fish¹

2013

mar technol soc j

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The screw propeller has been the mainstay of marine propulsion, but new developments in biomimetic propulsion can provide advantages in terms of speed, maneuverability, efficiency, and stealth. The diversity of aquatic animals provides designs for drag-based paddling and lift-based oscillatory hydrofoils that can be incorporated into engineered propulsive systems for enhanced performance. While the screw propeller will remain the prominent propulsive device, the choice of alternative biomimetic propulsive systems will be dependent on particular applications, where the specifications dictate improved performance criteria.

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Section: Figurementioning

confidence: 99%

Advantages of Natural Propulsive Systems

Fish¹

2013

mar technol soc j

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“…Briefly, the mesoglea was fabricated from soft silicone material with tensile elastic modulus of 56 KPa [30] (live jellyfish have elastic modulus on the order of 0.9 MPA [31] ) and physical dimensions (bell diameter = 164 mm) within the range of their natural counterpart. Detailed description of physical properties of the materials used for construction of all the components can be found elsewhere [32] . The propulsive muscles consisted of BISMAC actuators arranged radially around the bell at angles of 45° from each other.…”

Section: Methodsmentioning

confidence: 99%

“…The propulsive muscles consisted of BISMAC actuators arranged radially around the bell at angles of 45° from each other. Extensive computational and structural modeling of robotic jellyfish has been conducted to optimize the transient deformation behavior at BISMAC and segmented locations, tune the effectiveness of the joint design, and understand the role of material variables in robotic jellyfish [32] . The passive region along the bell margin, referred to as the flap, was constructed from the same silicon material as the rest of the bell.…”

Section: Methodsmentioning

confidence: 99%

Biomimetic and Live Medusae Reveal the Mechanistic Advantages of a Flexible Bell Margin

et al. 2012

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Flexible bell margins are characteristic components of rowing medusan morphologies and are expected to contribute towards their high propulsive efficiency. However, the mechanistic basis of thrust augmentation by flexible propulsors remained unresolved, so the impact of bell margin flexibility on medusan swimming has also remained unresolved. We used biomimetic robotic jellyfish vehicles to elucidate that propulsive thrust enhancement by flexible medusan bell margins relies upon fluid dynamic interactions between entrained flows at the inflexion point of the exumbrella and flows expelled from under the bell. Coalescence of flows from these two regions resulted in enhanced fluid circulation and, therefore, thrust augmentation for flexible margins of both medusan vehicles and living medusae. Using particle image velocimetry (PIV) data we estimated pressure fields to demonstrate a mechanistic basis of enhanced flows associated with the flexible bell margin. Performance of vehicles with flexible margins was further enhanced by vortex interactions that occur during bell expansion. Hydrodynamic and performance similarities between robotic vehicles and live animals demonstrated that the propulsive advantages of flexible margins found in nature can be emulated by human-engineered propulsors. Although medusae are simple animal models for description of this process, these results may contribute towards understanding the performance of flexible margins among other animal lineages.

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“…For a two parameter model, G = c 10 + c 01 2 is the shear modulus, but for higher order models, c mn are just coefficients of m powers of (I 1 − 3) and n powers of (I 2 − 3). Table 1 compares the EcoFlex silicone model parameters taken from Joshi et al [33] with that of natural mesoglea and candidate hydrogel materials for artificial mesoglea. Shear modulus calculated from the model provides a good basis for comparison of material stiffness irrespective of co-ordinate system.…”

Section: Mooney Rivlin Modelmentioning

confidence: 99%

Aurelia auritaInspired Artificial Mesoglea

Joshi

Villanueva

Smith

et al. 2013

Integrated Ferroelectrics

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In this preliminary study, we report the mechanical and dielectric properties of polyvinyl alcohol (PVA)-ferritin hydrogel. This material was found to exhibit close resemblance to Aurelia aurita (jellyfish) mesoglea in terms of stiffness modulus and water content. Systematic experiments were conducted on natural jellyfish to identify its compression modulus a function of deformation. In compressive testing Aurelia aurita mesoglea was found to exhibit nonlinear modulus in the range of −10 kPa to 70 kPa depending upon the compressive strain (0-50% strain). The negative stiffness is an artifact of tensile force experienced by the specimen at the beginning of the test due to surface tension. PVA hydrogels with 60% water to dimethyl sulfoxide (DMSO) ratio without ferritin particle (H60) and PVA hydrogels with 80% water to DMSO ratio with ferritin particle (F80) provided a good alternative to natural jellyfish mesoglea exhibiting shear modulus of 33.06 Pa and 39.99 Pa respectively as compared to 4.75 Pa for Aurelia aurita mesoglea. This is a significantly better match compared to the 1041.67 Pa shear modulus of Ecoflex, a soft polymer material commonly used in biomimetic robotics. A Mooney Rivlin model suggests that H60 and F80 compositions are about 6.9 times and 8.4 times stiffer than natural Aurelia aurtia mesoglea whereas Ecoflex is 219 times as stiff. Nanocomposite hydrogel consisting of PVA matrix and ferritin nanoparticles were found to exhibit higher durability over regular PVA hydrogels and had more consistent properties due to increased cross-linking at ferritin nanoparticle sites. The ferritin nanoparticles were found to act as springs, increasing the modulus by increasing the surface area of the cross-linked polymer chains and disrupting long linear chain patterns of the polymer. Natural Aurelia aurita was found to have water content of 96.3% with a standard deviation of 0.57% as compared to 85% water content of PVA-ferritin hydrogels. Use of this material in the design of biomimetic unmanned underwater vehicles is expected to reduce the power consumption, increase swimming efficiency, and better replicate the rowing kinematics of naturally occurring Aurelia aurita.

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Modeling of Artificial Aurelia aurita Bell Deformation

Cited by 7 publications

References 0 publications

Advantages of Natural Propulsive Systems

Advantages of Natural Propulsive Systems

Biomimetic and Live Medusae Reveal the Mechanistic Advantages of a Flexible Bell Margin

Aurelia auritaInspired Artificial Mesoglea

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