Damage Detection Of Typical Aircraft Structures Based On Sequential Non-linear Least-square Estimation

Contrary to the extended Kalman filter and the least square estimation, the sequential non-linear least square estimation has significant advantages in terms of the stability and convergence of the solution as well as the computational efforts involved. For the complex structure, especially the m-dof structure, the technique also has many disadvantages in terms of the computational efforts and efficiency involved. In order to apply the technique to the complex structure, we can make use of substructure analysis method and model reduction method to reduce the degree of freedom of the complex structure. Based on substructure analysis method and model reduction method, the sequential non-linear least square estimation is used to simulate rod-plate structure and beam-plate structure. Simulation results demonstrate that the computational effort and efficiency can be largely improved by using substructure analysis method and model reduction method.Stiffened plate is widely adopted in the aerospace structure for its high strength. In order to simulate the dynamic characteristics of the stiffened plate and to evaluate the possible damage of stiffened plate during the normal operation or right after a major disaster, it is important to develop a suitable finite element model. Based on shell element and beam element which considers shear self-lock effect, the paper establishes a finite element model. The accuracy and effectiveness of the approach have been demonstrated using simulation results. Finally, the paper establishes two experiments. According to compare the difference of the natural characteristics between finite element model and the experiment, the first experiment demonstrates the rationality of the finite element model. To compare the difference of equivalent stiffness between the experiment and the theoretical value, the second experiment demonstrates the efficiency and accuracy of the approach in damage identification of stiffened plate.