Identification Of Structural Damage Based On Modal Strain Energy

The general engineering structure were under the long term external static or dynamic loads in service stage,engineering structure would inevitably happen to a certain degree of damage in the partial or the whole.As the partial damage accumulated in service stage,the engineering structure would happen to the partial or whole failure.The positioning and recognition of existing state of damage of the structure was necessary,when conducting the maintenance or reinforcement of the existing engineering structure.The traditional method for structural damage identification was difficult to operate,and precision was not enough.The Research on gradually attention to the importance of the structural dynamic characteristics used in structural damage identification was recognized by the researchers.The relationship between the structural dynamic characteristics and structural damages has been found by the researchers.Based on the research of the relationship between the structural dynamic characteristics and structural damages,a variety of the structure damage identification method and index were put forward including the damage identification method and index based on modal strain energy.The existing structural damage identification method based on modal strain energy mainly included two kinds,they were the damage identification method and index based on variation of modal strain energy and variation of modal strain energy ratio.The research of these two methods was conducted in this paper.First of all,based on the modal strain energy of the two methods of structural damage identification and damage degree of estimation method has carried on the theoretical derivation.The damage location and damage degree to estimate formula were concluded.Taking a plane truss structure as the research object using the method of finite element analysis,two damage detection methods to verified the damage index of different damage conditions of plane truss structure is used to estimate location and damage degree,verified the applicability of the two kinds of damage identification method,and compared two methods of damage location and damage degree of the accuracy of estimation.The research results showed that the damage identification method based on the variation of the modal strain energy ratio is superior to the damage identification method based on modal strain energy variation ratio,which in the case of unknown damage units,damage degree is shallow,interference unit is more,it is difficult to get precise results of damage identification;The former in different damage cases have more accurate identification results;In terms of damage estimation,damage identification method based on modal strain energy variation rate is better than variation rate based on modal strain energy ratio of damage identification methods,but both in structural damage identification accuracy is not ideal.