News Release

Prof Steve WaiChing Sun wins Air Force's Young Investigator Program Award

Grant and Award Announcement

Columbia University School of Engineering and Applied Science

Simulation of Fracture and Fragmentation of Geological Materials Due to High Impact Loading

image: This is a simulation of fracture and fragmentation of geological materials due to high impact loading. view more 

Credit: Steve WaiChing Sun, Columbia Engineering

Prof Steve WaiChing Sun Wins Air Force's Young Investigator Program Award to Model Load Response of Granular Materials

Steve WaiChing Sun, assistant professor of civil engineering and engineering mechanics at Columbia Engineering, has won a three-year, $360,000 2017 Young Investigator Research Program (YIP) grant, awarded by the Air Force Office of Scientific Research (AFOSR). He is one of 58 researchers from 41 research institutions to be honored with this early career award. His winning project--"Modeling the High-rate Responses of Wetted Granular Materials Across Scales and the Third-party Replicable Validation Exercises Utilizing 3D Printers"--was selected from more than 230 proposals to AFOSR's YIP program, which fosters creative basic research in science and engineering and the development of outstanding young principal investigators graduated within five years of receiving their PhDs.

Sun works in the fields of theoretical and computational solid mechanics, poromechanics, and multiscale modeling of fully coupled multi-physical systems, looking to improve predictions of large-scale field problems with insight from small-scale observations and simulations. His research is focused on advancing the understanding on multiphase materials under extreme conditions and expanding predictive capabilities for related engineering applications, including geological carbon sequestration, hydraulic fracture, and nuclear waste disposal.

Sun will use the YIP award to lead a combined experiential-modeling effort to help understand the high-strain-rate responses of wetted granular materials to impact loadings released into the soil, such as blasts, explosion, munitions, subsurface exploration, ground improvement, and ballistic vulnerability of military structures. One key component of his YIP project is the introduction of 3D printing to create experimental prototypes that can be replicated and validated by other researchers.

Sun's project has two goals: First, he will introduce new numerical models that make more accurate and efficient predictions on how granular materials respond to high-rate loading using multiscale modeling techniques. This advancement requires better fracture and fragmentation models that are specific to the granular materials, as well as theories and techniques that link nanoscale simulations to field-scale engineering problems with consistency.

Secondly, he plans to develop a systemic and unbiased way to allow other researchers to challenge his results and findings by reproducing his work using 3D printers and open-source codes developed by his team. Sun's 3D printing techniques will enable other researchers to reproduce the same synthetic particles of the same particular size, shape, and material properties used in Sun's research. By making enough data available, he hopes to allow other researchers to perform the same simulations, experiments, and validation exercises as he did. "They can even challenge our results easily," he observes. "A critical issue we want to address is maintaining replication, corroboration, and transparency of research results, and we hope that other researchers will reach out to us and point out our shortcomings so that we all can learn from each other." He adds, "Granular material is the second most handled material in the global industry--second only to water--so the fundamental knowledge we gain will have far-reaching consequences, from helping engineers make more efficient and safer designs for mining and containment of underground explosions to assessment of earthquake damages. It is essential that we foster collaboration because that is how we will advance our field." In 2015, Sun also received the U.S. Army's Young Investigator Program award from Army Research Office to model how microscopic water and air seepages inside each pore of granular materials, such as sand, silt, and sediment, affect the bearing capacity and stability of the ground. In addition to the YIP awards, Sun recently won a three-year $800,000 grant from the U.S. Department of Energy's Nuclear Energy University Programs, which supports university-led nuclear energy research and development projects to develop innovative technologies and solutions.

His project, "An Integrated Multiscale Experimental-Numerical Analysis on Reconsolidation of Salt-Clay Mixture for Disposal of Heat-Generating Waste," will study the thermal-mechanical-hydrologic-chemical coupling effect on reconsolidated granular (or crushed) salt-clay mixture used for seal systems of shafts and drifts in salt repositories. "We think that adding some amount of clay in the re-consolidated clay mixture may make salt, an almost impermeable material, even less permeable so that these materials can be used as sealant for nuclear waste storage sites," he says. "We will be modeling and developing numerical simulations of a broad range of scenarios to see if that's the case and to understand how and why such a small amount of clay makes such a big difference on the engineering properties of the salt."



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