Before June 26th, Chris Budrow was a doctoral student at CHESS, working with his advisor Matt Miller. Now, he is Dr. Christopher Budrow.
As a graduate student, Chris was a staple at CHESS, engaging closely with the InSitu group and helping support outreach efforts by representing CHESS in Washington, DC, and participating his knowledge in the new tour video. His close work with Caterpillar helped steer his studies of applying high-energy X-ray diffraction to quantify multi-axial residual stress gradients.
Abstract of his Thesis:
Synchrotron based high-energy x-ray diffraction (HEXD) is an indispensable tool for measuring multi-axial stress gradients because it is able to non-destructively probe the interior of crystalline solids. The residual stress profile induced by carburization was studied intensely and a new lattice parameter correction method was develop. With this new method multi-axial stresses and stress triaxiality were determined through the case. An important aspect of this method was applying the traction-free surface condition (a mechanical constraint) to determine a surface lattice parameter (a materials problem). The idea of applying mechanical constraints was further developed by incorporating finite elements to impose mechanical constrains over an experimentally measured stress field. The mechanical constraints revealed stress gradients that were obscured by the relatively large gage volumes. Finally, the strain measurements that were used to calculate stress were studied in an effort to make measurements more quickly. Optimum measurement schemes were developed that are constrained by possible experimental configurations and dependent on the input stress state. These developments serve to advance residual stress measurements using HEXD, and elevate it one step closer to becoming a readily applied engineering and industry tool.