Application of dynamic system identification to timber beams. II

In a companion paper, a method of global nondestructive evaluation (NDE) fo r identifying local damage and decay in timber beams was developed and veri fied analytically using a finite-element model of a timber beam. The previo usly presented method of damage localization employs experimental modal ana lysis and an algorithm that monitors changes in modal strain energy between the mode shapes of a damaged beam with respect to the undamaged state of t he beam. In this second part of a two-part paper, experimental laboratory t ests on simply supported timber beams are presented to verify the capabilit ies and determine the limitations of the proposed method of NDE in locating simulated damage in simply supported timber beams. Due to the natural vari ability inherent within a timber beam, the required severity of inflicted d amage before the algorithm could correctly identify damage location was a 5 .08-cm (2-in.) deep saw cut in a beam with a depth of 15.88 cm (6.25 in.). For practical applications, the proposed technique could be used to identif y the presence and general location of severe decay or damage, and if neede d, more refined NDE techniques could be used to map the specific region aff ected by the decay or damage.