Experiments Demonstrate Potential of New Materials for Additive Manufacturing

American architect Frank Lloyd Wright sought to free the imagination by countering the conventional wisdom of his age, saying, “Form follows function - that has been misunderstood. Form and function should be one, joined in a spiritual union.” Faculty and students at the University of Virginia’s School of Engineering are achieving this union through materials science research in additive manufacturing, envisioning the efficient production of buildings that integrate beauty, sustainability and purpose.

“Humans can pretty much imagine any kind of structure or product, and 3-D printing makes it possible to replicate whatever we can dream up,” Ji Ma, an assistant professor in the University of Virginia Department of Materials Science and Engineering, said. “What makes our group unique is our ability to control the material properties of the objects printed. Discoveries of materials’ transformation during the process of 3-D printing will allow us to produce building materials and whole structures that are as creative as those who inhabit them, and culturally attuned to the communities in which they are placed.”

Ma pursued research in additive manufacturing during his commercially focused post-doc work at Texas A&M University. He quickly realized that additive manufacturers needed a better understanding of how the intense heat generated by the laser changes the properties of metals, in order to meet performance criteria of 3-D-printed objects. Put more plainly, the steel that goes into the machine is not the same when it comes out. The search for answers to this problem brought Ma to UVA Engineering. UVA’s approach integrates geometrics, composite materials and multi-functional materials to yield significant gains in efficiency, compared to a single path or approach. 

“UVA is one of the few organizations to look at additive manufacturing from a materials point of view, to engineer new materials with desired behaviors or qualities,” Ma said. “If I could, I’d make everything strong and ductile everywhere, but there is a tradeoff: Generally speaking, the stronger a material, the less ductile it is, and vice versa. If we can’t continuously make a material both stronger and more ductile, we may be able to make it ductile in the places where needed, and to make it strong in locations where it is most beneficial to be strong.”

Over the past year, Ma has focused on setting up a facility for metals additive manufacturing within the materials science and engineering department. Ma’s work is benefitting from a grant award to professors Jim Fitz-Gerald and Rob Kelly that purchased high-end equipment including three 3-D printers.

3-D printing enables the team to design in properties at a micro-scale, with precision. “We can change properties such as strength and flexibility within the same piece of material or alloy based on the laser treatment. We can also create new materials with the desired properties, something conventional manufacturing methods cannot do.” 

Here’s how it works. Controlling shape comes from creating or drafting a computer-aided design file; controlling properties comes from di.aling in the strength of the laser, along with its movement speed and scanning pattern. The printers use laser powder bed fusion—applying a heat source to consolidate material in powder form to produce a solid 3-D object—to design properties into pieces made with steel, titanium, nickel or a composite alloy. Ma and his students then use an electron microscope to observe changes and draw conclusions about how the materials behave singly and in combination, under specific laser treatments.

In addition to metals, Ma is also working on 3-D printing of concrete to make manufactured buildings. Ma’s research with concrete materials promises to make manufactured buildings more attractive and functional. For example, Ma’s students are trying out two different ways to make a cement-concrete mix set faster or slower, to design and 3-D print overhangs and domes. Connor Wynkoop, a third-year mechanical engineering major, investigating the creation of a fast-setting epoxy to coat cement, while Seth Engel, an M.S. student in Engineering Systems and Environment, is working on ways to predict what kind of structure can be successfully printed, given the property of the concrete as it sets

Ma enjoyed introducing materials science and engineering to the school’s undergraduates in the spring and looks forward to teaching an introduction to engineering course in the fall to incoming first-year students. “I hope I inspire my undergrad students to continue learning on their own. This is the best outcome,” Ma said.

Noting that undergraduate engineering students learn how to use computer-aided design tools, Ma seeks to inspire students with his vision for the future. “Imagine using computer-aided design to create an intricate object, using a paint brush to pinpoint desired properties of the material, and running that design through a 3-D printer that can layer in the engineered materials to match.”

Summing up a philosophy that guides his research and teaching, Ma said, “Our goal is to remove restrictions. You can create anything you want virtually; our materials science and engineering effort will help the physical world keep pace, to create what the imagination can conceive.”