Aug 28, 2017 | By Benedict

Researchers from the Technical University of Delft and the Technical University of Denmark have developed a new way to create bone-like porous infill in 3D printed parts. The technique can be achieved on several kinds of 3D printer.

Earlier this year, we reported on an exciting 3D printing research project involving several European technical universities. Seeking to create realistic bone-like structures, the group developed a novel way to produce bone-like porous infill, resulting in strong and lightweight 3D printed parts whose infill is tailored to the object.

That same research group has now returned with a major improvement to its bone infill method, optimizing both the boundary shell and the porous infill used in the technique. TU Delft assistant professor Jun Wu says the improvements could be “very useful” for engineering design and other applications.

The method builds upon two existing techniques for generating 3D printable models: a coating approach, “to obtain an optimized shell that is filled uniformly with a prescribed porous base material,” and an infill approach, “which generates optimized, non-uniform infill within a prescribed shell.”

In the exciting new development, the Europe-based researchers assign two sets of design variables: one defining the base and the coating, the other defining the infill structures. The resulting intermediate density distributions are then "unified by a material interpolation model into a physical density field, upon which the compliance is minimized."

In other words, the researchers are treating infill and shell as two highly interlinked concepts, the benefits of each only able to be maximized with two-way optimization.

What this ultimately means is that the researchers can now automatically generate optimized shell-infill composites for 3D printing, allowing engineers and other 3D printer users to create parts with the structural integrity of bone, but tailored for very specific uses and processes.

The process even generates completely different infill patterns depending on the shape and size of the printed object.

“The optimized shell infill shows some interesting geometric patterns,” Wu explains. “Elongated infill is found in the uni-axially loaded bars, while crossing infill can be observed at the joints connecting these bars.”

Of course, the bone-like nature of some infill patterns doesn’t mean the researchers are trying to replicate human bones for things like medical models. Instead, they think this porous infill generating procedure could have an extremely wide scope, proving that—sometimes—the best inspiration can be found from within.

Wu adds: “With the increasing fabrication flexibility offered by additive manufacturing, it is expected that such tailor-made structures will find many industrial applications.”

The researchers have the numbers to back up their claims too. In their research paper, they claim that the effectiveness the shell-infill model “has been confirmed through numerical tests,” concluding that “optimized, non-uniform infill performs better than uniform infill for the same material volume.”

The new research paper, “Minimum Compliance Topology Optimization of Shell-Infill Composites for Additive Manufacturing,” can be found here. Its authors were Wu, Anders Clausen, and Ole Sigmund.



Posted in 3D Printing Technology



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