IMPROVEMENTS IN THE DYNAWORKS? ISSPA IDENTIFICATION MODULE

摘要

A modal identification method is proposed in theDynaWorks? software: the ISSPA method(Identification of Structural Systems Parameters)developed by the University of Kassel (UKL) enablesto identify natural frequencies and modes, generalisedmasses and damping matrices from measured dynamicresponse data. These response data may be obtainedfrom vibration tests with either base excitation orsingle or multipoint force excitation.Improvements have been implemented in theDynaWorks? module to include new featurescorresponding to the original UKL method and in orderto be more efficient for industrial modal identification.Two methods, curve-fitting of measured frequencyresponse curves and Isspa, identification of physicalsystem matrices, can now be applied separately,depending on the user's selection based on resultsquality. Indeed in some cases, such as non diagonaldamping, ISSPA is more appropriated.A second improvement is implemented on the residualcorrection step used for better representation of theout-of-band modes: the correction is applied on thewhole frequency range consisting of one or more sub-ranges either with the correction obtained from curve-fitting, or with the static correction calculated frommeasured responses in the lowest frequency ranges, orwith user's values.The third feature is the response synthesis using a non-diagonal damping matrix in the case of non-proportional damping, in conjunction with the realmodes which represents an alternative to the complexmodes formulation which is normally used in the caseof non-proportional damping.The method is finally applied on an industrial structurewith base excitation. And the results are presented inthis article.