Improved Damage Location Accuracy Using Strain Energy-Based Mode Selection Criteria

A method is presented for selecting the subset of identified structural vibration modes to be used in finite element model correlation for structural damage detection. The method is based on a ranking of the modes using measured modal strain energy, and is a function of only the measured modal parameters. It is shown that a mode selection strategy based on maximum modal strain energy produces more accurate update results than a strategy based on minimum frequency. Strategies that use the strain energy stored by modes in both the undamaged and damaged structural configuration are considered. It is demonstrated that more accurate results are obtained when the modes are selected using the maximum strain energy stored in the damaged structural configuration. The mode selection techniques are * Presented as Paper 93-1481 entitled “Selection of Experimental Modal Data Sets for Damage Detection via Model Update,” at the 34th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, La Jolla, CA, April 1993. † Technical Staff Member, Engineering Analysis Group (ESA-EA), Mail Stop P946, Los Alamos National Laboratory, Los Alamos, NM, 87545. Member AIAA. ‡ Assistant Professor, Department of Mechanical Engineering of Soils, Structures, and Materials. Member AIAA ** Associate Professor, Center for Aerospace Structures and Department of Aerospace Engineering Sciences. Senior Member AIAA. †† Professor, Center for Aerospace Structures and Department of Aerospace Engineering Sciences. Senior Member AIAA. Improved Damage Location Accuracy Using Strain Energy-Based Mode Selection Criteria Scott W. Doebling, Francois M. Hemez, Lee D. Peterson, Charbel Farhat 1/3/97 Page 2 of 35 applied to the results of a damage detection experiment on a suspended truss structure that has a large amount of localized modal behavior.