Researchers at Lawrence Livermore National Laboratory (LLNL) have laid claim as the first team to 3-D print aerospace-grade carbon fiber composites. The laboratory said it hopes the developments leads to the “greater control and optimization of the lightweight, yet stronger than steel material.”
“The mantra is ‘if you could make everything out of carbon fiber, you would’ — it’s potentially the ultimate material,” explained Jim Lewicki, principal investigator of the research. “It’s been waiting in the wings for years because it’s so difficult to make in complex shapes. But with 3D printing, you could potentially make anything out of carbon fiber.”
As LLNL explains, carbon fiber is typically 3-D printing by physically winding the filaments around a mandrel or by weaving the fibers together like a wicker basket. Lewicki says this can result in finished products that are limited to either flat or cylindrical shapes.
However, according to LLNL, the researchers were able to print several complex 3D structures through a modified Direct Ink Writing (DIW) 3-D printing process. Lewicki and his team also developed and patented a new chemistry that can cure the material in seconds instead of hours, and used the Lab’s high performance computing capabilities to develop accurate models of the flow of carbon fiber filaments.
Lewicki says this was possible through simulation. A group of engineers performed computational modeling on LLNL’s supercomputers. LLNL says the engineers needed to simulate thousands of carbon fibers as they emerged from the ink nozzle to find out how to best align them during the process.
“We developed a numerical code to simulate a non-Newtonian liquid polymer resin with a dispersion of carbon fibers. With this code, we can simulate evolution of the fiber orientations in 3D under different printing conditions,” said fluid analyst Yuliya Kanarska. “We were able to find the optimal fiber length and optimal performance, but it’s still a work in progress. Ongoing efforts are related to achieving even better alignment of the fibers by applying magnetic forces to stabilize them.”
The direct ink writing process also makes it possible to print parts with all the carbon fibers going the same direction within the microstructures, allowing them to outperform similar materials created with other methods done with random alignment. Through this process, researchers said they’re able to use two-thirds less carbon fiber and get the same material properties from the finished part.
The researchers will next turn to optimizing the process, figuring out the best places to lay down the carbon fiber to maximize performance.