MAE Seminar: Computer Simulation, a Powerful Tool for Studying Physical Systems

Abstract: The latest developments in computing power and technique make computer simulations more powerful tools to understand physical phenomena and solve engineering problems. In this talk, Kang will present three examples in which numerical simulations played a pivotal role in adding fundamental knowledge and suggesting a new structural/material design.

1. The semiconductor industries have reduced the size of semiconductor devices for higher packing density and better operating performance, but miniaturization also brought issues like RC delay and power dissipation. These issues can be overcome by using low k-materials, one of which is silica aerogel, whose permittivity can be much lower than conventional low k-materials by introducing high porosity. However, low-density structures (or highly porous structures) are usually known for weak mechanical strength, and can hardly maintain mechanical integrity under CMP (chemical-mechanical polishing), a typical process in semiconductor fabrication. Silica porous structures have been studied for both low permittivity and high mechanical strength, and a smart structure was suggested from FEM simulations.
2. Advances in surface engineering enable us to control wettability of a liquid droplet by surface patterning. Sometimes, the surface pattern can be so complex that an analytical model cannot predict wetting behavior and a numerical model replaces the role. A 2D numerical tool, based on the line tension model, has been developed and tested its predicting ability in Wenzel and Cash-Baxter modes. This tool contributed physical understanding of wetting phenomena of small liquid drops on rough surfaces and revealed some interesting findings overlooked from the conventional wetting theory.
3. In nuclear-fusion plants, facing materials in divertor are exposed to neutron irradiation and extreme thermal load and become deteriorated over time. It is not an easy task to predict the material behavior in this harsh condition by experiment. Using atomistic simulations, we investigated defect formation mechanism and microstructure change in W and its alloys, and shed a light on understanding the change in mechanical properties due to the irradiation.

Bio:  Kang earned his Ph.D. degree in 2011 in mechanical engineering at Stanford, and worked as a postdoctoral researcher at Los Alamos National Lab for two years before he joined the mechanical engineering department at Yonsei University, in Seoul, S. Korea. Currently, Kang runs the computational mechanics of materials lab and investigates physical problems such as deformation mechanisms in metal, the mechanical behavior of 2D materials, material behaviors in harsh environments, and wetting phenomena. Full journal publication list can be found at sites.google.com/site/kwkang.