Multiscale Simulations of Mechanical Behaviors of Iron: Yannick Mathews and Ngoc Le
Yannick
Mathews
Ngoc
Le
Major: Math
Mechanical Engineering and Honors
College
University: Morehouse
College WSU
Year: Senior
Junior
REU
Program: Mechanical
Engineering – Multiscale
Modeling
Advisors:
Professor Hussein M. Zbib and Professor Ioannis
Mastorakos
Iron is the sixth most abundant element in the universe and accounts for 95 percent of worldwide metal production. Its low cost and high strength makes it indispensible in engineering applications such as structural components for buildings, automobiles, and machine tools. This summer, two undergraduate students share a unique research project pertaining to defects in iron.
Senior Yannick Mathews researches the accumulation of vacancies in iron during irradiation while junior Ngoc Le researches the interaction mechanisms between defects and dislocations in iron. Together they are performing complex numerical simulations to investigate the interaction among defects that form when metals are exposed to intense radiation, such as every day exposure to the sun.
For his part of the research, Mathews performs molecular dynamics simulations to study the fundamental processes involved in the radiation damage in iron. During this process, an initial amount of energy is assigned to a random atom inside the lattice and the accumulation of damage is examined by recording how the atom collides with the neighboring atoms to create vacancies and interstitials. He is also investigating the effect of grains in the crystal and how their size and number affects the formation of defects at different temperatures.
Yannick Mathews works on his molecular dynamics simulations in the lab.
In material science, a dislocation is an irregularity within a crystal structure. The presence of dislocations strongly influences many of the properties of materials. Some types of dislocations can be visualized as being caused by the termination of a plane of atoms in the middle of a crystal.
Le’s part of the research is to study how the dislocations interact with other types of defects, namely prismatic loops, voids and second phase particles using atomistic simulations. The simulated material is bcc iron, which is used in nuclear industry mainly for cladding. The goal of Le’s research is to identify the critical parameters (dislocation capture radius, defects size, distance, temperature, etc.) in the dislocation – defects interaction and their role in the deformation behavior of irradiated materials.
Ngoc Le using atomistic simulations in the lab.
“Although the topic is complex and completely new to both of them,” says Hussein Zbib, professor and director of the School of Mechanical and Materials Engineering, “Yannick and Ngoc have been able to learn in a very short period of time to use a molecular dynamics simulation code to generate new results and shed new light on important phenomena. They are both very dedicated young researchers and eager to learn new ideas. I am delighted to have them working with us this summer.”
“I’m enjoying how independent based the research is,” Le says, “I am treated like a scientist and not like a student.”
“Learning the computer language was difficult,” admits Mathews. Both Mathews and Le agree that learning how to use the computer operating system Unix has been the hardest part of their research so far.
Mathews participated in the REU program last year at University of Washington but did not enjoy the research experience there. “At the end of my research program with UW, I did not feel any sense of accomplishment,” he explains. “But with the research I am conducting right now at WSU, I feel like I am achieving more in the scientific field and I could even get this research published.”
Le is also having a positive experience here. “The REU program has provided me with real work experience which I never seemed to get with internships.” She urges undergraduate students to participate in research programs because the experience looks great on resumes, provides good connections to those in your field, and is ideal for those wanting to attend graduate school.
After undergraduate school, Mathews plans to attend graduate school across the country and hopes to become an architect. Le, on the other hand, is now contemplating graduate school after seeing the kind of research she can do in her field of study. “The REU program has made me think about attending graduate school,” she says.
"The REU program has provided me with real work experience which I never seemed to get with internships," says Ngoc Le.
"I definitely want to participate again in the REU program at WSU," states Yannick Mathews.