Mode Selection for Offshore Platform Damage Identification Using CMSE Sensitivity

A sensitivity-based mode selection strategy for cross modal strain energy (CMSE) method is proposed to identify damage more effectively. The cross modal strain energy sensitivity is defined as the sensitivity index. For this purpose, the cross modal strain energy sensitivity to structural damage is deduced, and is used to select the preferable mode combinations that are sensitive to damage. By using the preferable mode combinations, the CMSE system is refined and the degree of ill-posedness of the CMSE system is reduced. A numerical study is conducted on an offshore platform structure to demonstrate the effectiveness of the proposed scheme. The performances of the CMSE method with and without using the mode selection strategy are compared in the presence of noise. Results show that: (1) the accuracy of damage localization is improved when only a few mode combinations are utilized; (2) On account of excluding substantial low-sensitivity mode combinations, the amount of computation is significantly reduced.