Research On Probability Of Detection And Damage Extension Monitoring Of Composites For Aircraft Structures

Currently, structural health monitoring technology has been greatly developed and applied in aviation area. Applying the structural health monitoring system to obtain the information about the damage characteristic and severity is of great significance to increase the security of structures and reduce the maintenance cost of aeronautical structures. The mature application of structural health monitoring system will have a huge impact on the future aircraft design. The probability of detection of the SHM system is an important index to evaluate the monitoring level and reliability of the system. Meanwhile, the damage extens ion monitor ing of aircraft structures is of great significance to promote the real application of the SHM system.This thesis focuses on researches about the probability of detection of the SHM system and damage extension monitoring of composites. First the wave packet signal energy and correlation coefficient of Lamb wave are extracted as the signal characteristics, and the probability of damage curve has been obtained by using the signal response analysis model. The POD curve of the fatigue crack in the lug joint structure and the delamination damage of composites have been obtained experimentally. Second, a damage index has been calculated based on the correlation coefficient of Lamb wave, and then an enhanced reconstruction algorithm for probability inspection of damage is applied to obtain a tomogram for damage identification. On this basis, the delamination damage extension monitoring of composites has been realized. At last, a full functioned dual module structural health monitoring system that is based on virtual instrument technology and algorithm develop ed is used for experiments about the probability of detection of the SHM system and damage extension monitoring of composites. The effectiveness and reliability of the structural health monitor ing is validated by experiments.