In the late 2020s, Fermilab will begin sending the world's most intense beam of neutrinos through Earth's crust to detectors in South Dakota for the international Deep Underground Neutrino Experiment, or DUNE. When the new PIP-II particle accelerator comes online, an intense beam of protons will travel near the speed of light through a series of underground accelerator components before passing through metallic windows and colliding with a stationary target to produce the neutrinos. Researchers intend to construct the windows out of a titanium alloy and are testing the fatigue endurance of samples exposed to proton beams to see how well they will perform in the new accelerator complex.