Modal damping measurement for damage detection

This paper describes the application of arrays of surface-bonded piezoelements to determine modal damping characteristics of a tested structure. This information may be used for structural damage detection or structural dynamics evaluation. Any array element can be used as a sender, to generate a mechanical signal sweeping the frequency range of interest. Thus induced mechanical vibrations can be picked up either by the sender, or by another transducer. Modal characteristics, and in particular damping levels, are obtained using standard modal analysis methods from the resulting frequency transfer function. Since structural or material damage is frequently associated with changes in damping, the method described in this paper can be applied for structural health monitoring. It is expected that the approach presented will be particularly useful for testing light-weight and micro-structures.