Locating damages of space trusses by combining cross-model modal strain energy and wavelet transform

Abstract

To effectively locate damages of a space truss which usually has hundreds of elements, a new damage index is proposed by combining the cross-model modal strain energy (CMSE) and the wavelet transform (WT). Firstly, the novel CMSE are introduced to construct the damage index CMSEI. It is noted that the traditional modal strain energy (MSE) is calculated based only on mode shapes of the same model, i.e., the undamaged structure or the damaged structure. In contrast, the CMSE is computed by simultaneously utilizing mode shapes from two different models, i.e., both undamaged and damaged structures. Secondly, the WT is further conducted on the space-domain sequence composed of elemental values of the CMSEI, with high-frequency detail coefficients extracted to form the new damage index WT_CMSEI. Finally, damages are located for the elements with outstanding values of the WT_CMSEI. A space truss with as many as 504 elements is numerically analyzed. Results show that the proposed WT_CMSEI can better indicate damage locations than widely used indexes based on traditional MSE. It presents high robustness to resist the influences of noise, and can effectively decrease the disturbances from other undamaged elements. This study provides a potential application of the WT_CMSEI in damage localization for large-scale space trusses which have many elements.