STRUCTURAL DAMAGE IDENTIFICATION USING ASSIGNED PARTIAL EIGENSTRUCTURE

A method of identifying damaged structural elements from measured moda l data using an incomplete measurement set is presented. The method us es a mathematical optimization strategy to minimize deviations between measured and analytical modal frequencies and partial mode shapes. Da mage is identified by determining the stiffness change to a finite ele ment model required to match the measured data of the damaged structur e, Damaged elements are obtained directly from the results of the cost -function minimization because the allowed structural changes are cons istent with the original finite element formulation. The cost-function minimization is based on an assigned partial eigenstructure algorithm in which the physical properties of the structural elements are treat ed as control variables, which are chosen to achieve the measured part ial eigenstructure. An iterative solution is used to solve the nonline ar optimization problem. Experimental results are reported for a canti levered eight-bay truss assembly consisting of 104 elements.