Study Of Sructure Dmage Identification Based On The Strain Modal

With the increasement of service life and aging of the material, the structure of material may have had an injury in the use of the process, such as appearence of cracks affected by all kinds of natural disasters, environmental corrosion, overload and material fatigue effect, and the wear of mechanical structure in in use process. It not only affects the functional integrity of the structure, but also easily causes safety accidents, loss to the property of the country, people, and even a threat to life safety. Therefore, it is very important to study the method for structural damage detection.Modal analysis is an very important method of damage detection, and compared with the displacement modal parameters of a class, the emergence of the parameters on the stress and strain injury, location and damage degree is more sensitive. Many domestic and foreign scholars studies in damage for strain identification, and there are a lot of achievements.According to the research scheme of theoretical derivation and numerical simulation of mutual authentication, study the change discipline of strain modal structural damage.First, this paper expounds the structural damage identification at home and abroad research situation, development trends, the different structure damage identification method of damage index, as well as the advantages and disadvantages of different methods; Then, is derived from the basic equations of general linear vibration strain modal expression and the strain modal model, and the basic principle of strain modal; Secondly, this paper introduces the theory of modal analysis based on the finite element software and the basic process, using the finite element analysis software ANSYS to establish analysis model and different degree of damage model, the simulation analysis to extract the strain modal value; Finally, according to the results of numerical simulation, calculating the model of displacement mode and strain modal analysis, draw the curve fitting and the damage of mutant strain modal criteria.