Method for vibration analysis
OwnerRune Brincker, Palle Anderseninventors
Life of this patent
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Abstract
Output-only modal testing of an object. Vibrations are excited in said object and measured by a number of vibration sensitive detectors. From the data of the measurements, a spectral density matrix function is determined. From this density matrix, auto spectral densities for the individual modes are identified performing a decomposition based on the Singular Value Decomposition technique. From the auto spectral densities of the individual modes, natural frequencies and damping ratios for the modes can be estimated, and from the singular vectors of the Singular Value Decomposition, the modes shapes can be estimated.
Claims10
Method for testing an object with respect to its vibration modes, comprising exciting vibrations in said object, measuring said excited vibrations by at least one vibration sensitive detector, and obtaining data quantitative of said excited vibrations of said object, wherein the method further comprises;
- determining a spectral density function
- identifying in said spectral density function at least one auto spectral density function corresponding to a single degree of freedom system and obtaining a decomposition of said excited vibrations into mutually independent vibration modes.
Method for testing an object with respect to its vibration modes, comprising exciting vibrations in said object, measuring said excited vibrations by at least one vibration sensitive detector, and obtaining data quantitative of said excited vibrations of said object, wherein the method further comprises
- determining a spectral density function
- identifying in said spectral density function at least one auto spectral density function corresponding to a single degree of freedom system and obtaining a decomposition of said excited vibrations into mutually independent vibration modes,
- wherein the determination of said spectral density function comprises Fast Fourier Transform, and wherein the determination of said spectral density function further comprises Random Decrement Transform of said data preceded by the Fast Fourier Transform.
Method for testing an object with respect to its vibration modes, comprising exciting vibrations in said object, measuring said excited vibrations by at least one vibration sensitive detector, and obtaining data quantitative of said excited vibrations of said object, wherein the method further comprises
- determining a spectral density function
- identifying in said spectral density function at least one auto spectral density function corresponding to a single degree of freedom system and obtaining a decomposition of said excited vibrations into mutually independent vibration modes,
- wherein said determination of said spectral density function comprises the derivative of the covariance function obtained by the Random Decrement Transform of the time data.
Dependencies are inferred from the claim text.