The modal distribution method: a new statistical algorithm for analyzing measured acceleration data

Bert Sweetman; Myoungkeun Choi

doi:10.1117/12.658024

11 April 2006 The modal distribution method: a new statistical algorithm for analyzing measured acceleration data

Bert Sweetman, Myoungkeun Choi

Proceedings Volume 6174, Smart Structures and Materials 2006: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems; 61742H (2006) https://doi.org/10.1117/12.658024
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2006, San Diego, California, United States

Abstract

A new statistical method is proposed to quantify the significance of changes in mean frequencies of individual modal vibrations of measured structural response data. In this new method, called the modal distribution method, a power spectrum of measured structural response resulting from a Fourier transform is interpreted as being a series of independent modal responses. Each modal response is isolated over a frequency range and treated as a statistical distribution. The first two spectral moments are calculated directly from each of these distributions. A combined statistical comparison of the means of modal frequencies in separate data windows is used to produce a quantitative significance level of the observed differences between power spectra. Significant changes between these spectra indicate a change in the underlying process, such as damage detection in a structural health monitoring application. The method is general and may find a broad variety of applications, but it seems particularly well suited for structural health monitoring applications because the excitation is not required as input. An example is presented based on measured full-scale acceleration data from a drilling riser. To validate the new method, a power spectrum resulting from the field data is idealized to a target spectrum with known mean and variance of each mode. The idealized spectrum is subtly changed and new acceleration time-histories are simulated from these modified spectra to asses the effectiveness of the new method. The modal distribution method is found to be very effective at detecting subtle changes of mean modal frequencies.

Citation Download Citation

Bert Sweetman and Myoungkeun Choi "The modal distribution method: a new statistical algorithm for analyzing measured acceleration data", Proc. SPIE 6174, Smart Structures and Materials 2006: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, 61742H (11 April 2006); https://doi.org/10.1117/12.658024

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available