August 10, 2011
The decision to come to The University of Texas at Austin was a natural one for Julian Hallai, an engineering mechanics PhD candidate in his fifth year. After finishing his Bachelor's and Master's degrees in marine engineering and naval architecture at the University of Sao Paulo in Brazil and working in the field with offshore pipelines for four years, he knew he wanted to work with an expert in pipelines. Our own Professor Stelios Kyriakides is among the best in the world, so Hallai packed his bags for Austin. (Dr. Kyriakides is director of the Center for Research in Mechanics of Solids, Structures and Materials.)
"It's a very high-level school and it's a small department, so we're able to have contact with all the students and professors and get to know them well," Hallai said. "We have the best researchers and professors."
Hallai's industry years were split between two years at INTECSEA (main office in Houston) and two years at PETROBRAS, where he worked on the design of high-temperature and high-pressure pipelines. His interest in the mechanical behavior of pipelines led him to his research on the behavior of pipelines bent during installation.
The pipelines are constructed from low-carbon steel in which a phenomenon called Lüders' Bands occurs: bands of plastically deformed material coexist with undeformed material. This is a material instability that can interact with other structural instabilities, especially during reel-lay installation where a pipeline is built on land, wound around a large reel and then unwound from a ship offshore.
"We're investigating what happens when we bend pipelines with certain material characteristics around the reel," he said. "We need to understand their behavior and understand our limits."
Hallai said he's fascinated with this research because he gets to investigate the relationship between the material instabilities of the steel and the structural instabilities of the pipeline itself. The minute calculations in the give-and-take of this relationship can have major consequences if companies aren't aware of a pipeline's limits.
"The bottom line is, whenever you're designing pipelines, bending is often involved, so it's important to know how much you can bend these pipelines," Hallai explained. "We're trying to determine how much we can bend them safely, which could be during their installation, normal operation or due to some unforeseen circumstances. If you don't know, you have the risk of overloading the pipeline and having it rupture."
Hallai expects to graduate within the next two years and then hopes to return to the industry and find a research position at a major oil company.
