Xtc. Man et al., VIBRATION MONITORING OF SLOTTED BEAMS USING AN ANALYTICAL MODEL, The Journal of the Acoustical Society of America, 102(1), 1997, pp. 382-390
This paper reports part of a research program aimed at developing the
scientific basis for vibration monitoring in rapid and automatic globa
l inspection of structures for faults. Slotted steel beams in various
conditions were used as experimental samples. A mathematical model of
the slotted beam's vibration was solved using a perturbation method. R
elationships between the defect parameters and the vibration signature
showed a strong dependence of the modal frequency on the slot charact
eristics, including location and size. The method is computationally e
fficient, robust and could be used for on-line signal processing. The
experimental modal parameters were determined from the mobility functi
on calculated from the excitation and response signals. The modal freq
uencies and their shifts were then used to quantify the slot. A test o
f 11 beams with various conditions demonstrated that the slot can be c
haracterized inversely. Frequency shift contours which were numericall
y calculated from the analytical model were used to do this, The slot
locations were assessed with great accuracy, although the slot depths
were estimated to be larger than the actual values, due to the limitat
ion of the perturbation method. (C) 1997 Acoustical Society of America
.