Arthur T Knackerbracket has processed the following story:
Identifying deteriorating infrastructure can be as challenging as fixing it. However, researchers at Tohoku University have made this process easier with the development of an innovative new material.
The material responds to mechanical stimuli by recording stress history through a luminescent effect called an afterglow. This information is stored for a long time, and by applying the material to the surfaces of structures, researchers can observe changes in the afterglow to determine the amount of stress the material has experienced.
“What makes our material truly innovative is that it operates without a power supply, complex equipment, or on-site observation and is easily combined with IoT technology,” points out Tohoku University professor and corresponding author of the study, Chao-Nan Xu.
In Japan, aging infrastructure has become a significant problem, leading to an increased demand for new diagnostic technologies that prevent accidents and/or extend the life of structures.
Mechanoluminescent materials exhibit luminescence when mechanically stimulated, and technologies such as crack detection and stress visualization have been developed by applying this material to the surface of structures. But the luminescence can only be observed at the moment of mechanical stimulation, and information about past mechanical stimuli cannot be retrieved.
Researchers have explored various materials capable of recording past mechanical loading histories. These materials typically combine stress-luminescent materials with photosensitive materials, creating a system where the material emits light in response to mechanical stress, and this light can be preserved and later analyzed to reconstruct the stress history. However, these materials face several challenges: complex layering structures, dark reactions, and long-term recording performance. Additionally, while certain fluorophores reveal past loading history when subjected to heat, the application has been limited to materials capable of withstanding high temperatures.
Xu and her colleagues discovered a simple and environmentally friendly method to record stress using Pr-doped Li0.12 Na0.88 NbO3 (LNNO). This LNNO had a mechanical recording functionality, meaning it could retrieve even past stress events.
To retrieve past stress information, LNNO is applied as a coating on the surface of an object and then irradiated with a flashlight. The afterglow produced by LNNO can be measured using cameras or light sensors. The study demonstrated that the afterglow image matches quantitatively with the results obtained through finite element method analysis. Additionally, the research confirmed that LNNO retains this stress information even after a period of five months.
“Our findings are expected to alleviate the shortage of manpower in structural diagnosis, and lower costs,” adds Xu.
Reference: “Direct recording and reading of mechanical force by afterglow evaluation of multi-piezo mechanoluminescent material Li0.12Na0.88NbO3 on well-designed morphotropic phase boundary” by
Tomoki Uchiyama, Taisei Atsumi, Koki Otonari, Yuki Fujio, Xu-Guang Zheng and Chao-Nan Xu, 25 April 2024, Applied Physics Letters.
DOI: 10.1063/5.0209065
Also involved in the study was Tomoki Uchiyama, an assistant professor at Tohoku University, along with undergraduate students Taisei Atsumi and Koki Otonari. Yuki Fujio from the National Institute of Advanced Industrial Science and Technology and Xu-Guang Zheng from Saga University and Tohoku University.
(Score: 4, Interesting) by Runaway1956 on Sunday September 01, @12:15PM (2 children)
In the US, crumbling infrastructure is often simply not repaired when it is found. https://www.reuters.com/world/us/collapsed-pittsburgh-bridge-is-one-44000-poor-condition-us-2022-01-28/ [reuters.com] https://www.reuters.com/world/us/collapsed-pittsburgh-bridge-is-one-44000-poor-condition-us-2022-01-28/ [reuters.com]
That bridge that caught all the sensational headlines had been "inspected" regularly, and often enough, the condition of the bridge was misinterpreted and misreported. Some reports were more accurate, prompting closer inspections. But, the bridge was not condemned or repaired.
Parenthetically, that bridge used an unusual design, so inspectors often did not understand which structural members were load bearing, and therefore, critical to the bridge's integrity.
The DOT at the federal and the state levels need to simply condemn rotted out structures, close them down, and render them unusable to prevent future disasters. Better to close down a weakened bridge, than to wait for the bridge to collapse. We've seen some real disasters with bridges collapsing in the past.
What I'm trying to say is, adding a new tool to the inspector's tool boxes isn't going to accomplish anything, if the required repairs aren't made when damage is discovered.
A MAN Just Won a Gold Medal for Punching a Woman in the Face
(Score: 3, Interesting) by janrinok on Sunday September 01, @01:03PM
I agree, and it isn't just a US problem. I have seen the same in Europe.
I am not interested in knowing who people are or where they live. My interest starts and stops at our servers.
(Score: 2) by krishnoid on Sunday September 01, @02:27PM
Giving inspectors better tools is great for honest, conscientious inspectors, but not when the building process is so broken that it weaves the municipal inspectors [youtu.be] into the problem.
(Score: 4, Funny) by krishnoid on Sunday September 01, @03:04PM (1 child)
Usually I thought the afterglow means you can't remember what was stressing you out before. I think they're spending too much time in the lab.
(Score: 1, Informative) by Anonymous Coward on Monday September 02, @11:14PM
Here are some pictures of brittle lacquer stress coat, along with a nice explanation of the technique. While not "digital", it is fast and a perfectly good way to visualize stress concentrations that might lead to failures.
https://harshbhundiya.wixsite.com/worldofmechanics/post/a-lost-art-using-brittle-coatings-to-measure-strain-in-complicated-structures [wixsite.com]
I can remember seeing plastic scale models of car unibodies and other car parts in Detroit engineering labs as recently as the late 1990s. They were made to scale (including thickness) and were used for this type of testing. The low modulus of elasticity of the plastic meant that the required loads to deflect the structures were small. At least some of the coatings fluoresced under UV lighting and the color photos really showed what was going on.
One of these facilities was in a room with a descriptive name on the door:
Stress Lab