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The new mechanophore could be used for field-testing structures like wind turbines for interior cracks, even years after the structures been erected.
A team at the National Institute of Standards and Technology (NIST) has developed a tool to monitor changes in widely used composite materials known as fiber reinforced polymers (FRPs), which can be found in everything from aerospace and infrastructure to wind turbines. The new tool, integrated into these materials, can help measure the damage that occurs as they age.
“This gives us the ability to develop better, more fatigue-resistant composites,” said NIST chemist Jeff Gilman. “We can see when the fiber starts to break. We now have a way to quantify the damage.”
Since the 1960s, scientists have been experimenting with ways to make FRPs lighter and stronger. This has often meant testing the bond between fiber and resin. As reported in a previous publication, the NIST team added small molecules that fluoresce after the impact of mechanical force. These molecules, called “mechanophores,” change color or light up, helping identify tiny nanometer-sized openings or cracks between the fiber and resin.
The NIST team has taken this technology to the next level by incorporating the mechanophore throughout the composite resin. Although not noticeable to the naked eye, the newest approach allows scientists to use special microscopy imaging techniques to measure FRP damage. The approach incorporates a minute amount (less than 0.1% mass) of a fluorescent dye called rhodamine that causes no appreciable changes in the material’s physical properties.
If the new mechanophore is embedded in structures made of FRP, field testing for fatigue could ..
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