3D-Printed Strain Sensors Could Spot Damage Aboard Ships
A 3D printable strain sensor developed by University of Michigan engineers could provide the U.S. Navy and commercial shippers with a more accurate, less expensive way to assess damage to their vessels, helping to keep sailors safe in the aftermath of an attack or storm. Called the Strain Application Sensor (SAS), the new device detects tiny flexing movements in the metal parts of ships -movements that can alert crews to damage before cracks or other visual signs can be seen by the naked eye. This can be vital information when a ship has been damaged and crews need to quickly determine what to do next. The SAS sensor can precisely measure strain without the need for power or data connections. Made of 3D-printed plastic at a cost of a few dollars each, the sensors can be attached quickly with magnets. Mark Groden, the sensor's inventor and a graduate researcher at the U-M college of Naval Architecture & Marine Engineering, predicts they'll be in use within the next year.
Transcript
00:00:00 Stress is important to know because like a paper clip bent too many times back and forth, if you stress something many times you get what's called structural fatigue and structural fatigue too many times over many cycles with too great a stress range results in catastrophic failure. In the case of the ship that's from the wave loading. So my research is focused on a particularly challenging problem. The monitoring of structural health of ships. As you probably know they're over 1,000 feet long and the locations that we're looking to measure for structural details or deformation are interspersed throughout the ship and separated by water tight compartments.
00:00:35 And what we came up with is the world's first 3D printable strain gauge. SAS is the strain amplification sensor. We call it that because it operates using a series of levers and mechanical systems to amplify strain. The SAS provides in real time the stresses that a ship is experiencing. And because of that we can get a sense of the structural degradation for the construction of ships, and thereby the safety of the vessel at any point in its life cycle. That's one component of the SAS. The other is the SAS is a tool that can be used by not only the crew, but also those who are brought out to rescue the ship to understand the stresses and the forces that
00:01:14 are taking place on it. That way they can understand oh, do we actually need to abandon the ship or can we stay on it? Outside of visually seeing a crack or seeing a really significant what we call permanent set so permanent deformation of the outer shell of the ship, this would be the only other indication that they would have that the structure is in fact beginning to fail. Really right now they just rely upon visual indicators because there does not exist a very well rolled out system for structural health monitoring of ships. SAS can be attached to the material with magnets, and SAS is standalone, which means that it doesn't require power or data acquisition cables or system.
00:01:55 It's 3D printable, which means that we can also adjust parameters of the sensor for every single sensor that's produced. SAS is almost infinitely tunable so to speak. So we provide a very efficient tool to gather this data both for the crew and for the salvers and thereby we increase the safety and reduce the risk of these situations. 90% of goods by value are moved by ships and so they're operating 24hrs a day to provide us with almost everything we touch on a daily basis. Currently there isn't a cost effective way to monitor the structural health of a vessel and SAS, although it's not a comprehensive solution, it's a component and it's moving us in the direction of being able to provide ship owners and operators with structural
00:02:46 health monitoring capabilities on their ship and give them a way to acquire the data to make decisions on inspection and repairs that they don't currently have.