07/15/20: Prof. Lee heads UMass Amherst portion of new NSF Project.

Assistant Professor Jae-Hwang Lee of the Mechanical and Industrial Engineering Department is the principal investigator for UMass Amherst on a three-year, $700,000 project, funded by the National Science Foundation (NSF), to develop pioneering high-performance materials required by many of the world’s most significant industries. Lee is collaborating on the NSF project with Rutgers University principal investigator Professor Jonathan Singer and co-principal investigator Assimina Pelegri.

The UMass portion of the NSF grant is $304,999, and the Rutgers segment is $397,276.

As Lee explains about the NSF project, “The rate-dependent and temperature-dependent mechanical responses of porous micro- and nano-composites will provide the core knowledge of high-performance, lightweight materials and protective coatings, which are required by automotive, aerospace, and defense industries.”

According to Lee, “The Rutgers team will produce hierarchical composite materials and will perform near static mechanical characterization. My [UMass] team will perform the micro-ballistic characterization (laser-induced projectile impact testing or LIPIT) to understand the composite materials’ mechanical properties under extreme deformation.”

Lee also observes that, in addition to the existing dynamic mechanical analysis, the energy loss spectra from the proposed micro-ballistic method being performed by his UMass team will open a new path to discovering high-strain-rate rheological properties of various viscoelastic materials that have complex phases.

As background to this NSF grant, the research team’s abstract explains that porous materials are ubiquitous in applications ranging from filtration and construction to ones in extreme environments, such as the Arctic, deep sea, and space. However, the methods of manufacturing these materials often require bulk processing techniques, and it can be difficult to tune the structure and composition deterministically and independently.

In response to these factors, as the NSF research abstract states, “This collaborative proposal employs self-limiting electrospray deposition (SLED) to create controlled libraries of porous microfilms, enabling rapid screening of their characteristic material and architecture parameters while facilitating customized property tunability.”

The researchers say they will undertake mechanical analysis covering testing conditions from quasi-static to ballistic impact at room or elevated temperatures, thus allowing probing of the materials’ mechanical response to thermomechanical stimulus.

For ballistic analysis, according to Lee, his team will employ LIPIT testing, an innovative method of using laser-propelled microparticles to create controlled micro-ballistic impact.

“These experiments inform a semi-empirical model that in turn guides the direction of future experiments,” say the researchers, “ultimately leading to a platform to design and optimize porous materials for myriad applications, including exploration of SLED thin films as low-thickness alternatives to bulkier coatings.”

The project team consists of experts in SLED fabrication, nanomechanical testing and modeling, and micro-ballistic analysis. Meanwhile, each stage of these studies will be supported by multiscale computational simulations to create predictive models to guide both the course of the experiments to be conducted and the design of future materials. (July 2020)