Damage detection on a truss structure using Transmissibility Functions

A vibration based structural health monitoring technique based on Transmissibility Functions (TF) is presented in this paper. Advantages of this technique are that for its implementation measuring of the excitation force and the use of a model of the structure are not required. Basic characteristics of the capability to detect damage with the proposed technique regarding the analysed frequency range and the type of the analysed vibrations (longitudinal and flexural) are explained for a simple numerical model, comparable to a four-degree-of-freedom oscillator. The approaches are implemented on a numerical and an experimental model of a 40-bar space truss. It is demonstrated that the method is most effective in the low frequency range. All damaged elements of the simple model and 26 out of 28 investigated bars of the space truss model are detected when damaged. However, the method turns out to be sensitive to measurement uncertainty. Damage, comparable to that simulated o n the numerical model, could not be detected from the measurement results. However, the method yields good detection results for more serious damage. Generally, the presented method is capable to detect damaged elements of a complex structure. More research has to be done applying this method on other kinds of complex structures and on the sensitivity of the approach to different types and severities of damage.