A Numerical Method Study On Damage Identification Based On Structural Modal Information

The research purpose of damage identification of structure is to ensure the reliability and security of engineering structure and supply references to life estimation and maintenance of engineering structures. This is a proceeding subject always concerned by engineering area. A lot of recent papers of this area and different methods of damage identification have been summed up in this paper. But up to today, there is no satisfying one.The purpose of this paper is to understand the influence of damages on structures and compare the sensitivity of different parameters through modal analysis of damaged structures. Then, searching for new parameters in order to improve the precision of damage identification.This paper has two works:Firstly, based on curvature modal analysis of structure, it attained a new conception: differences of curvature modal. The numerical example is conducted through modal analysis of a simple supported beam with ANS YS software. From the result, natural frequency, curvature modal and differences of curvature modal are attained and compared the sensitivity of damage to different damage cases.Secondly, in order to find out a parmeters which has higher precision of damage identification, based on differential equation of free vibration, in combination with tested data (simulated by the computational results of finite element model) from damaged structure, residual vector is gained. Then with the use of general inverse and matrix projection theorem, a new parameter with good identification effect is deduced, which is called projection modulus of residual vector, and with which the damaged element is easily identified from other elements. And then, the damage factor of the damaged element is computed. Based on another computational example, this method is considered very sensitive to the damage in structure. It can identify the minuteness damage in structure andget good effect with first few modes.The work of this paper is based on the modal information of structures, which are identified by dynamic detection. So the paper has some theoretical significance and abroad application in terms of damage identification of engineering structure.