Most people will break at least one bone in their lifetimes, but just think about all the stress your bones experience without breaking. Scientists from Cornell University, Purdue University, and Case Western Reserve University have taken inspiration from bone to create more durable 3D-printed structures. This could eventually make 3D printing viable for high-stakes applications like construction and aircraft design.
Neither bones nor 3D printed objects are completely solid — that would make them too heavy. In 3D printing, projects often make use of various “infills” to make the structure stronger. In bones, the strength comes from spongy structures called trabeculae. In both cases, the key is collections of columns and beams that distribute the load evenly. The team found that creating modified versions of the “beams” inside human bone with 3D printing could produce objects that are much more durable.
Trabeculae consist of vertical plate-like struts and horizontal rod-like structures that act like columns and beams. When you’re young, the trabeculae in your bones are dense with these beams and columns. However, bones become less dense as you age, which is why breaks are more common among older people. The researchers wanted to see how much impact the two trabeculae structures had on strength.
The team suspected that the vertical plates do contribute to a bone’s stiffness and strength, but it’s the horizontal beams that make bone durable over the long-term. To demonstrate this, the team created a 3D printed model of trabeculae (below). They showed that the 3D printed trabeculae had similar mechanical properties to real bone. Then, they made a fully synthetic structure inspired by human bone and adjusted the horizontal beam thickness. They found that a 30 percent thicker beam resulted in a 100-fold increase in load-bearing capacity, offering compelling proof that the horizontal structures are the main contributor to strength.
Making the horizontal supports thicker did not significantly increase the weight of 3D-printed objects. That means we could eventually produce large 3D-printed structures that are durable and light enough to be transported from place to place. It could also make those Martian habitats a bit more sturdy. It could even help us better understand the changes happening in bones as they age, potentially leading to new treatments that reduce breaks.
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