Null-Subspace Analysis for Structural Damage Monitoringin Fatigue Testing of Luminaires

摘要

A damage detection method of mechanical system based on output measurements only and on thernsubspace identification concept is presented. The method uses the definition of null subspace analysis ofrnthe Hankel matrix. It is demonstrated to be sensitive to small-size structural damages and suitable forrncontinuous on-line monitoring. The measured response records of structures under environmental orrnartificial vibrations are assembled in the Hankel matrix that is further factorized into special subspaces.rnThe active subspace defined by the first principal components is shown to be orthonormal to the nullrnsubspace defined by the remaining principal components. Therefore, any evident increase of the residuesrnsignifies possible structural damages. The method is illustrated by an application to fatigue tests of a streetrnlighting device (luminaires). Experimental methods and numerical calculations on luminaires are simplyrndescribed and discussed. The test results show that the developed methods may be easily used torneffectively monitor the damage evolution during the fatigue tests.