Research

No carbon fiber necessary: Dr. Adrian Bowyer unlocks stronger 3D prints

In a blog post for RepRap Ltd. Dr. Adrian Bowyer, the inventor of self-replicating 3D printers and winner of our Outstanding Contribution to 3D Printing, has described a potential method for creating stronger 3D printed objects.

A novel approach, Dr. Bowyer’s method demonstrates a way of 3D printing fiber reinforcements without actually using a fiber-reinforced filament.

It’s not a trick (we promise.) Just an interesting experimental alternative to 100% infill.

Cube demonstrating Dr. Bowyer's concept for adding hollow cylinders to reinforce 3D prints. Image via RepRap Ltd.
Cube demonstrating Dr. Bowyer’s concept for adding hollow cylinders to reinforce 3D prints. Image via Dr. Adrian Bowyer/RepRap Ltd.

3D printing phantom fibers

Dr. Bowyer’s idea considers adding a selection of hollow cylinders to the interior of a 3D printed part. The rest of the object is 3D printed with ordinary infill so these cylinders, in a
way, act like an additional infill pattern. As Dr. Bowyer explains, “When the part is sliced the slicer will surround the cylinder with solid material automatically, making it like a length of strong fibre embedded in a weaker material (the print’s infill).”

In other words, rather than deliberate mistakes that actually make parts weaker, the cylinders act like glass or carbon fibers due to the inner walls that they create within the part.

3D printed components are often weaker on a particular axis, this is due to the fact that FFF 3D printed parts are anisotropic, “In particular they tend to be stronger in the layer directions (say X and Y) than in the Z direction,” explains Dr. Bowyer in a previous post linked to this concept. The orientation of these “fibers” then serves to counteract some of that imbalance.

“Of course, angled cylinders will be layered,” he adds, “but they should still be a lot stronger than infill.”

Putting it to the test

To put this concept into practice, Dr. Bowyer has created a sample hollow-fiber reinforced beam with a hole at the end for hanging weights.

Hollow fiber reinforced test beam. Image via Dr. Adrian Bowyer/RepRap Ltd.
Hollow fiber reinforced test beam. Image via Dr. Adrian Bowyer/RepRap Ltd.

He will then compare the stiffness between this part and a non-reinforced part with weight added. If the tests go in favor of the cylinder reinforcements, the plan is then to write code that will allow him to automatically add reinforcement cylinders based on weak areas identified by finite element analysis (FEA).

Another idea with the cylinders, and this time a dual nozzle 3D printer, is to make the majority of the object from one material, and fill the “fibers” in with another, stronger filament. This would save on material usage for sure but, if programmed properly, it could also help strengthen typically weak parts of an object.

Dr. Bowyer’s full post on “Fibres” can be found online here.

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Featured image shows Dr. Adrian Bowyer. Photo via Phaidon

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