Ph.D. Candidate Wins Outstanding Presentation from Society for Experimental Mechanics

Nicholas Bachus, a Ph.D. candidate in the Department of Mechanical and Aerospace Engineering, was awarded Outstanding Presentation in the Residual Stress Technical Division from the Society for Experimental Mechanics, or SEM, Annual Conference and Exposition, for his research paper on the Cold Expansion process as it relates to residual stress in materials.  

Advised by Mechanical and Aerospace Engineering Professor Michael Hill, Bachus' paper "Bulk Residual Stress Measurements for Model Validation of Cold Expansion of Geometrically Large Holes in 7050-T7451 Plates" discusses the Cold Expansion manufacturing process that aims to improve the service life of aircraft. Specifically, the talk, Bachus says, presented process model comparisons of the Cold Expansion process to high-fidelity residual stress measurements using mechanical and diffraction-based techniques.  

This work was in collaboration with the U.S. Air Force Research Laboratory, Fatigue Technology, Inc., Los Alamos National Laboratory, Cornell High Energy Synchrotron Source, and Hill's fatigue-focused firm Hill Engineering. Bachus indicates that it will be used moving forward to inform process models for fatigue life predictions and work will soon be submitted to a journal for publication. 

"There is a big push within the aerospace industry to not only extend the fatigue life of aircraft but also to improve fatigue life model predictions, so the scheduling of inspections and maintenance is more precise and accurate," he said. "This can reduce costs while increasing safety margins." 

SEM is an international organization that comprises members of academia, government and industry "who are committed to the interdisciplinary application, research and development, education, and active promotion of experimental methods." The annual conference focuses on the research and latest technologies pertaining to experimental mechanics, including fatigue and fracture, residual stress, thermomechanics and biological systems.