Simulation on the faults mechanism of wing structure

Structural health monitoring is a new research focus and has being paid more and more attention in engineering. Based on the traditional NDT, SHM improve the ability of faults detection, diagnosis and prognostics. Especially in aeronautics, SHM has been applied to monitor the aircraft status and guide its maintenance, with the aim to improve its reliability, safety and reduce the cost. The faults mechanism, which will directly determine the faults detection results and the precision of prognostics, can explain the reason and the subsequent responses of the faults. Research on the faults mechanism will be useful to determine the monitoring parameters and the corresponding faults characteristics. In this paper, taking the wings of a certain spacecraft as an example, its dynamic characteristics have been investigated with two type modes, joint failure and vibration effect. Based on the fault simulation with finite element method, the structure dynamic response can be obtained under the outer loads. That results show that the wing will not lose bearing capacity in the case of single joint failure. But its harmonic response frequency will reduce to 30Hz∼40Hz while it is 40Hz for undamaged wing. Taking the failure modes into account, the dynamic responses will be changed obviously. That means the failure excitation can be transferred to structure and change the dynamic characteristics of the wing. And the vibration excitation has regional and transient effect on the structure, its internal stress and local vibration near the failure zones will increase rapidly. The response spectral density curve with logarithmic coordinates of each node in wing model has been obtained by using frequency response, input PSD loading and damping field. The methods for failure diagnosis include spectral density curve, total RMS and autocorrelation function are applied to wing structure. The results show that the wing satisfies the design requirements from a structural point of view. Moreover, the faults mechanism can guide engineering experiments and faults diagnosis.