TY - GEN
T1 - Experimental investigation of the structural scattering due to impedance discontinuities on a cylindrical shell
AU - Glotzbecker, Ryan J.
AU - Hambric, Stephen A.
AU - Pollack, Martin L.
PY - 2005
Y1 - 2005
N2 - Experimental, numerical, and analytical work has shown that the response of a shell to a distributed force wave possesses unique characteristics which are dependent on the nature of structure attached to the shell. Specific characteristics which influence the response are the distribution of the discontinuities around the circumference (periodic/a-periodic), the impedance of the discontinuities relative to that of the shell, and the type of impedance (mass or stiffness). An experimental investigation into the harmonic scattering behavior of a shell due to mass discontinuities is presented in this paper. Knowledge of the key structural characteristics which influence scattering and their behavior will allow for a diagnostic tool when assessing the structural response of more complex cylindrical structures. Changes in structural response on a mode number basis as a result of the change in mass discontinuities are explored. Spatial Fourier analysis of both the input force and output response is used to provide a measure of the structural response matrix on a mode-by-mode basis. A distributed input force is simulated by applying forces around the circumference of the shell, then subsequently weighting the phase and amplitude of the measured transfer function according to the input force wave desired. This technique was applied to a shell in its unmodified condition, with periodic masses attached, and with a-periodic masses attached. Test results indicate that some harmonic scattering is present in the clean structure (no attached mass), likely due to non-ideal boundary conditions and the weld seam of the pipe used. Test results for the structure with periodically distributed masses indicate that response harmonics equal to the sum of input the harmonic number and an integer multiple of the number of discontinuities were excited. The structure with a-periodically distributed masses appears to scatter energy from the force harmonic into all response harmonics.
AB - Experimental, numerical, and analytical work has shown that the response of a shell to a distributed force wave possesses unique characteristics which are dependent on the nature of structure attached to the shell. Specific characteristics which influence the response are the distribution of the discontinuities around the circumference (periodic/a-periodic), the impedance of the discontinuities relative to that of the shell, and the type of impedance (mass or stiffness). An experimental investigation into the harmonic scattering behavior of a shell due to mass discontinuities is presented in this paper. Knowledge of the key structural characteristics which influence scattering and their behavior will allow for a diagnostic tool when assessing the structural response of more complex cylindrical structures. Changes in structural response on a mode number basis as a result of the change in mass discontinuities are explored. Spatial Fourier analysis of both the input force and output response is used to provide a measure of the structural response matrix on a mode-by-mode basis. A distributed input force is simulated by applying forces around the circumference of the shell, then subsequently weighting the phase and amplitude of the measured transfer function according to the input force wave desired. This technique was applied to a shell in its unmodified condition, with periodic masses attached, and with a-periodic masses attached. Test results indicate that some harmonic scattering is present in the clean structure (no attached mass), likely due to non-ideal boundary conditions and the weld seam of the pipe used. Test results for the structure with periodically distributed masses indicate that response harmonics equal to the sum of input the harmonic number and an integer multiple of the number of discontinuities were excited. The structure with a-periodically distributed masses appears to scatter energy from the force harmonic into all response harmonics.
UR - https://www.scopus.com/pages/publications/33645970695
UR - https://www.scopus.com/pages/publications/33645970695#tab=citedBy
U2 - 10.1115/IMECE2005-79724
DO - 10.1115/IMECE2005-79724
M3 - Conference contribution
AN - SCOPUS:33645970695
SN - 0791842258
SN - 9780791842256
T3 - American Society of Mechanical Engineers, Noise Control and Acoustics Division (Publication) NCA
SP - 263
EP - 269
BT - American Society of Mechanical Engineers, Noise Control and Acoustics Division (Publication) NCA
T2 - 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005
Y2 - 5 November 2005 through 11 November 2005
ER -