Researchers from the Technical University of Denmark have recently showcased two modern methods for repairing Continuous Fiber Composite (CFC) structures in a newly published paper. The study focused on fixing Continuous Fiber Reinforced Thermoplastic (CFRTP) samples using automated print in-situ repair and adhesive patch repair techniques.
The Advantages of In-situ Repair
The ability of CFRTP 3D printing to carry out repairs in-situ when mending composite parts is one of its major benefits. This allows for direct repairs on the component in question, eliminating the need for transportation. Apart from decreasing time and cost, it minimizes work interruptions. The versatility of the method also makes it suitable for mending parts with complicated shapes and internal structures.
The initial image was of an Anisoprint Composer 3D printer, the same type used in the study. This was provided for illustrative purposes.
The employment of CFC printing for structural repairs leads to mechanical characteristics that closely match the original composite structure. This becomes particularly beneficial when dealing with the restoration of high-performance load-bearing structures. In addition, CFC 3D printing provides greater precision and improved regulation over the repair process, guaranteeing precision and uniformity.
The practice involves using the exact needed material, trimming down material waste, thus presenting a more viable solution. Moreover, it seems to be a time-saving, cost-efficient, and sustainable technique for mending CFC structures, showcasing enhanced performance and prolonged lifespan.
Methodology
The samples were created using an Anisoprint FDM machine, which introduces continuous fiber into a thermoplastic matrix. The research explored the mechanical performance of the repaired samples through detailed tensile tests, a vital element in assessing the effectiveness of repair techniques.
An Instron universal testing machine was used in the evaluations, featuring a 250 kN load cell, ensuring a steady crosshead speed of 2 mm/min. Strain measurements were performed utilizing two 6 mm long single clip gauges that are tactically positioned on either side of the sample.
In the same vein, examinations of the microstructure offered beneficial understanding into the intricate design of the 3D printed composite samples. The micrographs of the cross-sections along with the side sections exposed a layered-type microstructure which accentuated the clear demarcations between the layers of the polycarbonate matrix and carbon fiber.
Conclusions
The conclusions gleaned significant understanding, validating the effectiveness of the suggested repair methods. Both the procedure of adhering patch and the print in-situ repairs exhibited potential in reinstating the original rigidity and resilience of the compromised samples to a significant extent.
Notably, the elastic modulus of damaged specimens saw remarkable improvements of 30% and 44% through adhesive patch and print in-situ repairs, respectively. The corresponding strength enhancements were substantial at 20% and 28%.
Toughness, a critical metric for material resilience, saw increases of 31% and 36% for adhesive patches and print in-situ repairs in damaged specimens.
Additionally, the analytical model developed by the researchers was able to predict the elastic modulus aligned closely with experimental measurements, affirming its reliability as a predictive tool.
Future Implications
Automated print in-situ repair has proven itself as the star of the show, evidently overtaking adhesive patch repair in terms of mechanical performance and dependability. It’s more than just its ability to restore original properties, the automated method holds essential implications for accurately predicting the remaining lifetime of repaired composite structures.
There is a possible outcome of reducing design safety factors and related expenses, which could pave new paths for industries depending on advanced composite materials.
You can peruse the complete (pre-proof) research paper, named “In-situ and adhesive repair of continuous fiber composites using 3D printing” in the Additive Manufacturing journal, available at this link.
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“Why did the 3D printer go to therapy? Because it had too many layers of unresolved issues!”
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