Octopuses inspire 3D-printed propulsion systems for boats
Now, their ability to flee quickly from predators has inspired a new propulsion system for boats and other water craft.
The Fraunhofer Institute for Manufacturing Engineering and Automation IPA, the researchers behind the new technology, explained how octopod escape predators:
"While they generally move along the ocean floor with their eight arms, they flee by swimming head-first, in line with the principles of propulsion. When the mollusk does this, water is taken into its mantle, which is then closed by contracting sphincter muscles. The water is then squirted back out at a high pressure through a funnel. The resulting propulsion pushes the octopus forward in the opposite direction. By changing the position of the funnel, the octopus can precisely steer its direction of travel."
The researchers mimicked this action a system made up of four elastomer balls with mechanical workings that create propulsion from sucking in water through an opening and then pushing it out. A valve prevents the water from flowing back out once it's brought in and then a hydraulic piston contracts the integrated cable structure like a muscle, pushing the water out of the ball. A motor pump moves the hydraulic piston.
“Our underwater actuator is well-suited for maneuvering small boats. It can also be used as a floating aid for water sport devices such as jet skis, surf boards, or scooters that pull divers into deep water. In contrast to ship propellers, it is quiet, and fish cannot get caught in it,” said Andreas Fischer, an engineer at IPA in Stuttgart.
The coolest part is that this system can be built using a 3D printer. They used a special process called fused deposition modeling where the polyurethane plastic was liquified and turned into filament for the printer to create the complex geometry using a soft plastic. Its flexibility lets it survive very high pressure and stress without breaking.