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Journal of Undergraduate Research

Keywords

microcracks, electromagnetic excitation, acoustic resonances

College

Physical and Mathematical Sciences

Department

Physics and Astronomy

Abstract

Stainless steel structures are often affected by stress corrosion cracking, which makes microscopic cracks that can go unnoticed and eventually cause the structure to fail. A useful method for detecting stress corrosion cracking is nonlinear resonant ultrasound spectroscopy (NRUS). NRUS involves vibrating a sample and looking for amplitude-dependent shifts in the sample’s resonance frequencies. NRUS tests are typically performed by driving vibrations in rods with piezoelectric transducers and measuring the amplitude-dependent shifts in the resonance frequencies. I am developing a different technique for driving the vibrations, which has never been used for NRUS. The technique uses a coil attached to the rod, which is placed in a strong magnetic field. Compared to the piezoelectric technique, which can only excite longitudinal vibrations, this electromagnetic technique allows us to excite three different types of vibrations in a rod sample: longitudinal, torsional (twisting), and bending vibrations, and conduct NRUS measurements for each type.

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