Scientists break new ground with 3-D printing composites
July 7, 2014
- "We can 3-D print structures with wiring, sensors or energy storage embedded in the structure."
Army Technology Magazine
- July/August 2014 Focus: 3-D Printing
ABERDEEN PROVING GROUND, Md. (July 7, 2014) -- When Army research and development investments in additive manufacturing pay off, future warriors who need hard-to-get devices, such as unmanned aerial vehicles or medical devices, may be able to print them on the spot.
Scientists from the U.S. Army Research Laboratory are searching for materials and technology to create multifunctionality. Larry R. "LJ" Holmes is the principal investigator for the lab's additive manufacturing material and technology development.
"DoD can't afford to wait for commercial industry to create this capability," he said. "Industry doesn't inherently understand our specific needs without ARL research informing them."
Holmes received a patent for a novel additive manufacturing technology used to create micro-composites, which can be tailored for specific end-use applications that require high-strength lightweight materials. The Field-Aided Laminar Composite, or FALCom process. Holmes worked in collaboration with the University of Wisconsin-Madison to address the defense science and technology community's need for agile manufacturing of systems.
The process uses electric fields to align and orient particles within a polymer system at any location and desired orientation during the additive manufacturing of a three-dimensional object. FALCom allows for a high degree of design freedom, especially with weapon systems like rotorcraft, which are tight on space. Holmes said the process is used to support personnel protection programs and has garnered interest from the Rapid Equipping Force. The REF harnesses current and emerging technologies as solutions to deployed Soldiers' urgent needs.
"FALCom can be used to make multifunctional parts," Holmes said. "Anytime we can add multifunctionality, we are helping with space and weight savings. Embedded sensing, embedded heat-sinks and embedded electronics -- all of these things help with trade space. FALCom offers a way of making these types of things with regard to 3-D printing," Holmes said.
Historically, 3-D printing has relied on commercially available materials like polymers, and it was used primarily for prototyping. For years, trends have moved toward total manufacturing, like building engine parts and robotic components with 3-D printing, said Dr. Jaret Riddick, a team lead within the ARL Vehicle Technology Directorate.
Riddick and Holmes, along with research engineer Ed Habtour, are among a cadre of scientists and engineers at Aberdeen Proving Ground, Md., investigating the development of materials and technologies that could be transitioned to industry or military program managers who make decisions about Soldiers' equipment.
"We can 3-D print structures with wiring, sensors or energy storage embedded in the structure," Habtour said. "It reduces weight."
Habtour uses 3-D printing to develop and transition technologies to other military organizations and small businesses based on the maturity of the technology.
Riddick said if these materials are to be used to manufacture real parts, as opposed to prototypes, the material properties must be well understood.
"The actual process of 3-D printing changes the properties," Riddick said. "For some processes involving metals, the temperature, spot size where the printer's laser points to melt the metal or the architecture, how the object is built one layer at a time, horizontally versus vertically, changes the material properties and performance."
Last fall, Army and Purdue University researchers, created a structure using brittle 3-D-printed materials with pseudo-ductile behavior, "which is somewhere between brittle and flexible," Habtour said.
Exploiting the pseudo-ductile behavior of logical structures, known as topologically interlocked structures, researchers showed improvements in energy absorption and dissipation, productivity and lower maintenance costs. The team developed computer models using commercial and open source code to provide an automated process for auto-generation of the geometries, models, materials assignments and code execution, Habtour said.
"The benefit for the Soldier is an aftereffect," Habtour said. "[It] would provide an excellent energy absorption and dissipation mechanism for future vehicles using additive manufacturing."
Army researchers used the fused deposition modeling 3-D printing process to create a structure with good energy absorption from materials that do not exhibit good absorption.
"Now we have a modeling tool, which wasn't available before," Riddick said. "We're planning to ultimately reduce maintenance and logistics burdens by being able to deploy the capability to produce the products for repair on-the-spot, rather than transporting them from far-off locations."
Riddick said a collaboration with Howard University is under way to build upon these results by measuring dynamic response of 3-D printed polymer materials fabricated with this process.
The Army Research Office funded Howard researchers to investigate high strain rate properties of materials. Results of testing show that dynamic response of the structures can be manipulated by 3-D printing.
"The challenges of moving additive manufacturing from a prototyping technique to an actual manufacturing capability are rooted in basic scientific research and fundamental advances," Riddick said.
"Additive manufacturing has the strong potential to increase the military's agility and efficiency but this is not exclusive to America," said Dr. Jeffrey Zabinsky, chief of ARL Materials and Manufacturing Science Division.
Zabinsky said 3-D printing may also provide adversaries with capabilities they have not had in the past.
"We will need to close the gaps and stay several steps ahead of our adversaries," he said.
The Army Research Laboratory is part of the U.S. Army Research, Development and Engineering Command, which has the mission to develop technology and engineering solutions for America's Soldiers.
RDECOM is a major subordinate command of the U.S. Army Materiel Command. AMC is the Army's premier provider of materiel readiness -- technology, acquisition support, materiel development, logistics power projection, and sustainment -- to the total force, across the spectrum of joint military operations. If a Soldier shoots it, drives it, flies it, wears it, eats it or communicates with it, AMC provides it.