Issue 29

E. Grande et alii, Frattura ed Integrità Strutturale, 29 (2014) 325-333; DOI: 10.3221/IGF-ESIS.29.28 332  =[  3 ,  5 ,  7 ]  =[  3 ,  4 ,  6 ] Figure 9 : rdi and MSECRj index vs. DF technique – M6,11D10N0.5 damage case (100 simulations).  =[  3 ,  5 ,  7 ]  =[  3 ,  4 ,  6 ] Figure 10 : MDF technique – M6,11D10N0.5 damage case (100 simulations) C ONCLUSIONS he approaches here proposed combines the use of some damage indicators with the evidence theory based on the Dempster’s rule of combination through a procedure devoted to obtain more reliable and evident information concerning the position of damage in linear systems. The results carried out with reference to the numerical applications reported in the paper have clearly underlined the ability of the proposed approach in improving the performances of damage indicators both in the case of single damage scenarios and in the case of multiple damage scenarios. In particular, the MDF have underlined a better capability to detect the location of damage with respect to the DF where a simple fusion is performed. Indeed, it has been observed that the MDF particularly emphasizes the values of damage indicators corresponding to the damaged members and, at the same time, leads to a significant reduction of the value of the indicators of the undamaged members. This peculiarity is indeed mainly due to the subsequently data-fusion multiple steps procedure which allows to refine the vectors of local decisions. The ability of the proposed approach has been also confirmed in the presence of scenarios characterized by damages with lower damage severity (stiffness reduction less than 5%). Nevertheless, although this aspect has not been analyzed in the present paper, in this case it has been observed a greater sensibility of the data fusion to the set of the selected modes of vibration. Although the proposed approaches have shown a sensibility to errors affecting the identified modes, as occurs for the classical approach based on the rdi and the MSECR, it has been observed that the most significant variations concern the only indicators corresponding to the damaged members; on the contrary, in the case of the classical approach, the indicators of all the members are significantly affected by the noise. Finally, as underlined in [6], the ability of the proposed approach in providing an efficient detection of the damage position in structures represents an important basis for the further step of the identification process that is the determination of the damage severity. Indeed, the precision of most of the methods available in the current literature [13] in detecting the damage amount is strongly dependent on the correct identification of the damage position. Moreover, the proposed data fusion approach could be generalized in order to improve not only the identification of the damage position but also the damage extent. 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 elements rdi index 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 elements MSE index 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 elements index from fusion rdi index MSE index datafusion 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 elements rdi index 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 elements MSE index 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 elements index from fusion rdi index MSE index datafusion 0 5 10 0 0.2 0.4 0.6 0.8 1 elements BPAs(rdie 2 ) Multiple DataFusion MDF - rdie 2 index 0 5 10 0 0.2 0.4 0.6 0.8 1 elements BPAs(MSECR j ) Multiple DataFusion MDF - MSECR j index 0 5 10 0 0.2 0.4 0.6 0.8 1 elements BPAs(rdie 2 ) Multiple DataFusionMDF - rdie 2 index 0 5 10 0 0.2 0.4 0.6 0.8 1 elements BPAs(MSECR j ) Multiple DataFusion MDF - MSECR j index