KINGSTON, R.I. – January 24, 2019 — Being on a ship in rough waters can be unsettling, to say the least. On a research vessel, turbulent waves can lead to more than motion sickness, it can result in valuable equipment being damaged.
When you’re aboard a research ship in the middle of the ocean and a piece of equipment breaks, returning to port to replace a part is not an option. However, what about using a 3D printer to generate critical equipment parts right on board, saving valuable time at sea?
Four University of Rhode Island ocean engineering students demonstrated that they not only could keep a 3D printer level while at sea, but they could replicate a piece of equipment that works as effectively as the original.
Josh Allder, Grady Bolan, Sean Nagle and Allison Redington were granted this rare opportunity last semester aboard the Okeanos Explorer, a research vessel operated by the National Oceanic and Atmospheric Administration (NOAA).
On stable ground, 3D printers have countless applications in many different industries. In an unstable environment, such as the ocean, many 3D printers are only effective if they remain in a perfectly level position while printing. These printers use a curable liquid resin. Any motion from a ship could cause the resin to slosh around.
Accompanied by ocean engineering faculty Stephen Licht and Brennan Phillips, the students had from the time they boarded the ship on Nov. 27 in San Juan, Puerto Rico to the time they disembarked on Dec. 2 in Nassau in the Bahamas to complete all stages of their project.
The research and testing at sea was part of the students’ senior capstone design project, which started in September.
Long before the students stepped foot on the ship, they had to become familiar with the printer they would be using, be able to simulate the motion they would experience at sea and figure out how to stabilize the printer in a dynamic environment to achieve accurate and effective results.
The printer the students worked with was a Formlabs Form2 SLA (stereolithography apparatus) printer, which is valued at $3,300-$5,000. It uses an ultraviolet (UV) curable liquid and a laser to cure the liquid layer by layer. This results in a more dense and higher-resolution print than the more commonly known extrusion style printers.
The four students performed batch prints, which included three long bone-shaped pieces, a small cube and a complex print referred to as the “Devil’s Playground.”
The bone-shaped prints were used for tensile testing. The cube enabled the students to see if the print had any deformities. The “Devils Playground” is a part that challenges the printer’s capabilities in great detail.
After examining the motion data from the Okeanos Explorer, the students created a motion simulation platform for the printer to simulate the movement of the ship and get some idea of how it might behave once onboard.
The team learned that there was an internal accelerometer, which determined if the printer was level throughout the print. If the printer was tilted, the software displayed an error message indicating the problem and automatically pausing the print. If their motion compensation scheme wasn’t adequate, the students would have to manually level the printer between each layer, which would add up to extremely long print times.
Once the students boarded the research vessel in San Juan, they mounted the printer on a GyroPro stabilization platform, which they rented for the trip. The GyroPro is most commonly used to stabilize IMAX cameras.
Next, they conducted a test print prior to the ship leaving the pier.
“We came up with a test matrix to evaluate how well the printer can perform different tasks,” said Allder, who is from Little Compton, Rhode Island. “That would allow us to quantitatively and qualitatively assess the mechanical properties of the results.”
After the ship left the dock, the team started its first print on open water. For further comparison, the students completed a set of prints using both passive and active stabilization methods, which the GyroPro allowed them to choose. They also performed one with the printer sitting on an unstabilized lab bench later in the trip.
With no time to spare, the team made sure the printer was running a print at all times. Therefore, the students devised a work schedule to have at least one person on duty to monitor the printer. The staggered 24-hour schedule had each team member work for four hours, be off for eight, work for eight hours, be off for four.
“It meant being up at some weird hours,” said Bolan, a Newport resident. “One of my four-hour shifts was from 2 to 6 a.m., but I was able to see the sunrise over Puerto Rico.”
Watching something print for hours on end is not the most exciting job. But because of the staggered schedule, the students were able to take breaks and enjoy their time onboard.
“We had time to go outside to get some fresh air, take a stroll around the ship, grab a coffee from the galley, watch downloaded movies, work out, eat ice cream, or get some homework done,” Bolan stated.
Once the students were done testing the printer and making sure it would produce an object to their desired specifications, they were ready to replicate an actual piece of equipment used for research.
The Okeanos Explorer, like other research vessels, is equipped with instruments called CTD’s (conductivity/temperature/depth), which can collect data while traveling through the water column. A version of these instruments was placed in round, translucent pressure housings that the students printed in 3D, one while onboard and one at URI.
To test the structural integrity of the housings, they were lowered to a depth of 200 meters. The engineering students calculated that the units would hold their shape and seal as deep as 310 meters.
“I was apprehensive while waiting for them to bring the housings back aboard the ship and into the lab,” said Nagle, a native of North Kingstown. “But I was ecstatic to see that both of the housings stayed watertight. As a proof of concept, this was a great success. We 3D printed a pressure housing on board a moving research vessel, using a type of printer that had never been brought to sea before.”
The students recorded all of the research they conducted prior to their trip and while on the ship in a 63-page document titled, “Stabilization System to Allow for 3D Printing in a Dynamic Environment.” The team concluded that they successfully used an SLA printer at sea, were able to isolate the printer from the ship’s motion and print a viable pressure housing.
“We are very pleased and excited by the work the students produced this semester,” said Licht and Phillips.
While working on the Okeanos Explorer, the students were given a tour of the ship. The behind-the-scenes look reaffirmed what they would like to do for a career after they graduate.
“Since I was little, I have always liked the idea of working on underwater vehicles, which is why I decided to study ocean engineering at URI,” said Redington, who is from Deale, Maryland. “After an amazing experience at sea, which hopefully won’t be my last, I am still mostly drawn to underwater vehicles.”
“The innovation and design components of this research project allowed me to grow as an engineer,” stated Allder. “These are skills that I can apply to anything in engineering, including underwater vehicles, which is my goal.”