MATERIAL SPECIAL................... Ultra strong 3D printed structures

MATERIAL SPECIAL Ultra strong 3D printed structures



A new 3D printed material build out of polymers, metals and ceramics, can withstand 1,60,000 times its own weight. It could be used to make parts for aircrafts and cars

Imagine a material with the same weight and density as aerogel ­ a material so light it's called `frozen smoke' ­ but with 10,000 times more stiffness. This material could have a profound impact on the aerospace and the auto industries as well as other applications where lightweight, high-stiffness and highstrength materials are needed.

Lawrence Livermore National Laboratory (LLNL) and Massachusetts Institute of Technology (MIT) researchers have developed a material with these properties using additive micromanufacturing processes. The findings are published in the journal Science.

The article describes the team's development of micro-architected metamaterials ­ artificial materials with properties not found in nature ­ that maintain a nearly constant stiffness per unit mass density, even at ultralow density.

MICRO-STEREOLITHOGRAPHY

 Most lightweight cellular materials have mechanical properties that degrade substantially with reduced density because their structural elements are more likely to bend under applied load. The team's metamaterials, however, exhibit ultrastiff properties across more than three orders of magnitude in density.

“These lightweight materials can withstand a load of at least 160,000 times their own weight,“ said Xiaoyu “Rayne“ Zheng, lead author of the Sci ence article. “The key to this ultrahigh stiffness is that all the micro-structural elements in this material are designed to be over constrained and do not bend under applied load.“

The observed high stiffness is shown to be true with multiple constituent materials such as polymers, metals and ceramics.

“Our micro-architected materials have properties that are governed by their geometric layout at the microscale, as opposed to chemical composition,“ said Chris Spadaccini, corresponding author of the article, who led the joint research team. “We fabricated these materials with projection microstereolithography.“

This additive micro-manufacturing process involves using a micro-mirror display chip to create high-fidelity 3D parts one layer at a time from photosensitive feedstock materials. It allows the team to rapidly generate materials with complex 3D micro-scale geometries that are otherwise challenging or in some cases, impossible to fabricate.

“Now we can print a stiff and resil ient material using a desktop machine,“ said MIT professor and key collaborator Nicholas Fang.

“This allows us to rapidly make many sample pieces and see how they behave mechanically.“

The team was able to build microlattices out of polymers, metals and ceramics. 

LIGHT MATERIAL, HEAVY LOADS

This approach could be useful anywhere there's a need for a combination of high stiffness (for load bearing), high strength, and light weight ­ such as in structures to be deployed in space, where every bit of weight adds significantly to the cost of launch. But Fang says there may also be applications at smaller scale, such as in batteries for portable devices, where reduced weight is also highly desirable.

Another property of these materials is that they conduct sound and elastic waves very uniformly, meaning they could lead to new acoustic metamaterials, Fang says, that could help control how waves bend over a curved surface.

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