Researchers at the Technology Innovation Institute’s [TII] Advanced Materials Research Centre have been exploring new techniques of joining composites with carbon fibre threads of 2-4 mm in diameter.
This will help in joining composite sheets or patching a damaged section of high-performance products like airplanes and racing cars, which are increasingly crafted from multiple sheets of composites formed of carbon fibre reinforced polymers, a TII release said.
Larger products like airplanes and cars require the assembly of multiple composite sheets into a finished product. And if an airplane suffers damage, technicians need to securely patch a fresh sheet of material around the damage.
But these joints where multiple sheets connect are not as strong as the rest of the composite sheet.
Overall structure
Prof Zhongwei Guan, Energy Absorption and Composite Materials, Executive Director at AMRC, said: “Usually, the repair patch leads to weakened overall structure. With this approach, we are trying to affix a repair patch with the same strength as the mother material.”
Researchers, manufacturers, and repair technicians have explored a variety of approaches for joining composite fabrics, including adhesives, rivets, nuts, and bolts, or a combination of these. A technician drills multiple holes in overlapping sections and affixes the rivets or bolts to connect and repair the area.
This included stitching the composite sheets using thin wires with a diameter usually less than 1 mm. The AMRC researchers are exploring the use of thicker threads. “It is important to balance out the strength of a thicker fibre thread against the effects of a larger diameter hole which weakens the fabric to be connected or repaired,” Prof Guan said.
Early days
This research is still in its early days because it is difficult to stitch using such thick fibre thread through a composite component with a large thickness. There are no machines to stitch these thick fibre threads with composite laminates or sandwich to date.
Now, the team is helping to analyse the relative performance of various kinds of single-lap and double-lap weaves. Once they have identified some of the best patterns and stitching techniques, they hope to develop a machine that can automate this process.-- TradeArabia News Service
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