EFFECTS OF DATA ACQUISITION CONDITIONS ON MODAL TESTING OF A SIMPLE STRUCTURE

摘要

The results of investigations conducted to determine the effects of data acquisition conditions on the estimation of modal parameters are presented. The varying conditions are excitation level, exciter location, transducer cable attachment, exciter suspension and excitation configuration (portable exciter versus driven-base). The test structure was a lightly damped steel beam and the first four bending modes were measured. The estimation of damping was found to be very sensitive to some test conditions, especially to the method of cable attachment. The estimated residues were fairly stable throughout the whole exercice. The results presented herein demonstrate quantitatively that damping estimates of a lightly damped structure can be significantly altered by inadequate emphasis on details. They show the importance of prudent preparation and performance of a modal test.