ME Student Awarded NASA Space Technology Research Fellowship (NSTRF)

December 15, 2015

Greenhall research sm
 University of Utah mechanical engineering  Ph.D. candidate, John Greenhall, advised by mechanical engineering assistant professor Bart Raeymaekers, received a 2015 NASA Space Technology Research Fellowship (NSTRF). NASA Space Technology Research Fellows perform research at their respective campuses and at NASA Centers and/or at nonprofit U.S. R&D laboratories.

Through this experience, NSTRF graduate researchers will have the opportunity to work collaboratively with leading engineers and scientists in the students’ chosen area of study; they will be able to take advantage of broader and/or deeper space technology research opportunities directly related to their educational and career objectives, acquire a more detailed understanding of the potential end applications of their space technology efforts, directly disseminate their research results within the NASA/nonprofit U.S. R&D lab community, and enhance their understanding of the research process.

Greenhall’s research is entitled, “Reinforcement of 3D printed nanocomposite materials using ultrasound alignment of carbon nanotubes.” The objective of his research is to understand how ultrasound waves can be used to create user-defined patterns of nanoparticles in a photopolymer resin, which will then be cured using a stereolithography 3D printing process. 3D printing is an attractive method to manufacture prototypes because highly complex geometries can be created with a single device and limited additional processing. This is especially appealing for space exploration and extraterrestrial colonization, where it is expensive and technically difficult to deliver parts from Earth, but on-site manufacturing capabilities are limited.

The critical obstacle that prevents 3D printed polymer parts from being used as actual mechanical components in engineering applications, is their lack of mechanical strength. To increase this strength, carbon nanotubes (CNTs) will be added to the polymer, aligned in patterns tailored to maximize the strength of the part, based on the anticipated mechanical loading of the part. Alignment will be achieved by creating ultrasound standing waves, which exert an acoustic radiation force on the nanoparticles, driving them to desired locations.

In contrast to other CNT alignment techniques, ultrasound alignment can be scaled to large areas and it does not restrict the final material shape. In addition, the nanoscale reinforcement could also be used to provide other functionality to the materials, including conductivity, electromagnetic shielding, or other thermal and electric properties. These composite materials attempt to take advantage of the unique properties of nanostructures in macroscale engineering applications. By creating a novel method to create high-strength nanocomposite structures with complex geometries, this research will result in significant advances in the fields of polymer matrix composite and in-space assembly, fabrication and repair research.

This project will involve:

  1. development of the ultrasound alignment technique within polymer;
  2. integration of the ultrasound alignment and stereolithography into a single device, capable of creating 3D printed nanocomposite structures; and
  3. analysis of the effects of aligned CNT reinforcement on the mechanical performance of the parts.

John Greenhall is a member of the Utah Tribology and Precision Engineering Laboratory.  Learn more about his and his colleagues’ research on their site.


The goal of NSTRF is to sponsor U.S. citizen and permanent resident graduate students who show significant potential to contribute to NASA’s goal of creating innovative new space technologies for our Nation’s science, exploration and economic future.   NASA Space Technology Fellows will perform innovative, space-technology research at their respective campuses and at NASA Centers and/or at nonprofit U.S. Research and Development (R&D) laboratories.  Awards are made in the form of training grants to accredited U.S. universities on behalf of individuals pursuing master’s or doctoral degrees, with the faculty advisor serving as the principal investigator.

In addition to Greenhalls faculty advisor, he will be matched with a technically relevant and community-engaged researcher, usually at a NASA Center, who will serve as his professional research collaborator.  The research collaborator will serve as the conduit into the larger technical community corresponding to Greenhall’s research interests.

The visiting technologist experience is an integral part of a NASA Space Technology Research Fellowship. Ten weeks per year is the target duration, though the actual weeks chosen (number and timeframe during the year) will depend upon Greenhall as the student, his faculty advisor, and the NASA or R&D lab research collaborator.


The Department of Mechanical Engineering at the University of Utah is committed to providing students with broad-based, rigorous and progressive education. By combining state-of-the-art facilities with renowned faculty, the department provides an education that gives students the necessary skills to become the next generation of innovators.