Resonances of Unconstrained Compressive, Shear and Flexural Waves in Free-Free Cylinder Specimens

자유단 공시체에 있어서 압축파, 전단파, 휨파의 공진특성

Shear wane velocity is important property for grasping the dynamic characteristics of material. It is has been used in various fields such as non-destructive testings of structures, seismic analysis of geotechnical structures and maintenance of concrete structure, and etc. Usually, shear wave velocities of rock cores and concrete cylinders are determined by free-free resonance tests, Shear wave measurement in free-free resonance tests is not straightforward, as compared with rod wave and flexural wane measurements. In This study, a new technique using resonance features of flexural and shear waves were proposed in which the nodal points for the fundamental mode of flexural waves were employed to generate and measure the shear waves with the flexural waves minimized. The real measurements for aluminum cylinders proved validity and reliability of the proposed algorithm. In addition to the proposed algorithm, the effects of material properties on elastic-wave velocities in resonance measurements were also studied. In summary, a new framework of the resonance measurements for shear-wave velocity determination was established, based on the results of this thesis.