Research On Operating Deflection Shapes And Operational Modal Analysis And Software Implementation

Operating Deflection Shapes (ODS) analysis and Operational Modal Analysis (OMA) havebecome the focus of research at home and abroad because they have the advantages of needn’tmeasure input forces, safety, and don’t influence the operating states of structures. ODS describes theactual deflection shape of the structure at specific time or frequency in operating states, while throughOMA, the modal parameters such as natural frequencies, damping ratio and modal shapes can beobtained. Combine the analysis results of both, the actual vibration deformation and dynamicperformance of structures in operating states can be totally understand, which have vital significancein structure condition monitoring, fault diagnosis and vibration source recognition, etc. Therefore, thispaper studies and realized the time and frequency domain ODS and a operational modal parametersidentification approach based on positive power spectral density--poly references Least SquareComplex Frequency domain (pLSCF) method, which have a strong anti-noise ability. The maincontents of this article are included as follows:（1） The basic properties of ODS, the differences and relationship between ODS and modalshape, the principle and measurement methods of time and frequency domain ODS are studied. Thecalculation of several frequency domain ODS functions and the differences between them areemphasized.（2） In order to better solve the low modal parameter identification accuracy in modal testwith big noise, the pLSCF and stabilization diagram marking method is studied deeply. Through asimulation case, the strong anti-noise ability of pLSCF method is verified, which also produces a clearstabilization diagram. Based on positive power spectral density, the application of pLSCF method inOMA is investigated. Through a simulation case, the modal parameter identification results betweenpLSCF method and professional modal analysis software MACEC are compared, which verify theeffectiveness of pLSCF method for OMA.（3） A ODS animation and OMA software named ODSMA is developed in MATLABplatform. The software can simulate the spatial response of structure’s ODSs by the way of slowmotion, which make observing the actual operating deformation of structures be an easy thing, thusidentify the excessive vibration positions; Combined with OMA, the dynamic properties of structuresunder running state can be comprehensively analyzed. The software is standardly programmed withfriendly interfaces, aided by rich mouse or keyboard control ways to reach a humanized operation. （4） By uses of FRF data measured on classical GARTEUR model and time domain responsedatas of a2D frame structure, the ODS animation function of ODSMA loaded by data obtained withor without input force measurement method is respectively verified. Through vibration modal test ona three-floor frame structure, each function of the software is totally applicated, the results show thatthe software can be operated stably and produce reliable results, therefore easily used for vibrationdeflection analysis and modal parameter identification of structures in operating states.