A recent study published in Polymers explores a novel approach to monitoring damage in carbon fiber-reinforced polymer (CFRP) composites, a material widely used in aerospace for its strength and thermal stability.
Study: Damage and Failure Monitoring of Aerospace Insulation Layers Based on Embedded Fiber Bragg Grating Sensors. Image Credit: Johan G/Shutterstock.com
For the study, the researchers integrated Fiber Bragg Grating (FBG) sensors into the composites to provide real-time data on structural health under extreme conditions. By tackling the challenges of high-temperature environments, this study offers new insights into enhancing the safety and performance of aerospace materials.
Background
In aerospace engineering, finding materials that can handle extreme environments while staying reliable and safe is a constant challenge. That’s where CFRP composites come in. They’re lightweight, incredibly strong, and resistant to heat, which makes them perfect for aerospace applications.
But even the best materials have their limits. CFRP composites often face high temperatures that can cause them to break down or fail structurally. Keeping an eye on this damage isn’t easy. Traditional monitoring methods tend to be intrusive and can’t provide the continuous data needed to catch problems early.
To solve this, researchers are exploring FBG sensors. These tiny sensors can be embedded directly into the composite material, where they monitor strain and temperature in real-time. They work by reflecting light; when the material is stressed, the wavelength of the reflected light shifts, offering a precise way to track what’s happening inside.
Study Overview
Building on this technology, the study focused on understanding how embedded FBG sensors monitor thermal decomposition and damage progression in CFRP composites, with the goal of improving the safety and reliability of aerospace materials.
The team started by creating a digital model of laminated CFRP plates using ABAQUS software. The plates were designed to match real-world aerospace materials, measuring 250 × 25 × 2.5 mm with 20 alternating layers oriented at 0° and 90°.
Next, they tested how these plates handled heat. Using a finite element simulation, they exposed the model to an environment where the temperature was cranked up to 650 °C, starting from 25 °C. They also set a surface heat exchange coefficient of 15 to mimic real conditions. The team tracked how the material broke down over time—at the beginning, after 50 seconds, and at the end of the simulation.
On top of that, they ran tensile tests to see how much force the material could handle before showing signs of strain or breaking. During this process, FBG sensors embedded in the plates monitored internal changes, giving real-time data without affecting the material’s strength.
Results and Discussion
The findings revealed a clear pattern: as heating time progressed, the thermal decomposition rate increased significantly. The surface closest to the heat (Z = 0 mm) saw the fastest breakdown, while the back surface (Z = -2.5 mm) stayed relatively cooler and more stable. This uneven heating creates weak spots, which is why understanding heat transfer in these materials is so important.
The tensile tests told a similar story. At lower loads, the material stretched predictably—strain increased steadily with the applied force. But as the load neared 3624 N, the material hit its limit. Strain spiked sharply, signaling the start of microcracks and deformation. At higher forces, some layers started to fail, forcing the material to redistribute the stress. This highlights why early damage detection is key—catching these signs early could prevent a total breakdown.
The real star here was the FBG sensors. They tracked everything in real-time, capturing how the material reacted to both heat and stress. This kind of data is invaluable for predicting when and where damage might happen, making it easier to plan maintenance and avoid failures in critical aerospace components.
Conclusion
This study shows how embedded FBG sensors can change the game for monitoring CFRP composites in aerospace. By combining computer simulations with hands-on tests, the researchers got a clear picture of how these materials respond to extreme conditions.
The big takeaway here is that real-time monitoring with FBG sensors is incredibly effective. These sensors make it easier to spot damage early, giving engineers the tools to improve safety and performance. Moving forward, refining this technology and expanding its use in different aerospace components could make a huge difference in building materials that last longer and perform better in tough environments.
Journal Reference
Yan G., Wan B., et al. (2024). Damage and Failure Monitoring of Aerospace Insulation Layers Based on Embedded Fiber Bragg Grating Sensors. Polymers 16(24), 3543. DOI: 10.3390/polym16243543, https://www.mdpi.com/2073-4360/16/24/3543