Experiments for damage location in a damped structure

In this paper, we present the results of an investigation of significant damping effects and the ability to locate damage. A three-bay, vertically cantilevered laboratory truss testbed was developed to exhibit beam-like response for the first three modes (a pair of first bending modes in orthogonal directions and a torsional mode). Truss members were removed from the testbed to simulate various damage scenarios with reduced stiffness. In addition, up to four visco-elastic damping struts were placed in the truss testbed in various configurations to affect the damping of certain modes of the structure. A comprehensive test matrix of damping and damage effects was designed and completed to construct the data base for the damping and damage identification evaluations. Two representative visco-elastic struts were also tested individually to determine their stiffness and damping characteristics. The damage detection process used the differences between pre- and post-damage vibration characteristics, along with a structural model, to successfully locate and quantify the extent of structural damage in all cases. Damping matrix models were also identified and evaluated.