Abstract
To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half.
Highlights
In recent years, large scale composite structures have been widely applied in large aircrafts [1,2,3].On-line impact monitoring of these structures on-board and off-board during their whole service lifetime is very important [2,3,4,5,6,7]
Considering the following two aspects, the phase synthesis time reversal impact imaging method is adopted based on some simplifications: (1) only the impact alarm region needs to be localized but not the accurate impact position because the digital monitor can only acquire digital sequences but not impact response signals; (2) for further study, a simple, stable and low power consumption method is more suitable because the whole method needs to be implemented in the Field programmable gates array (FPGA) to fulfill the on-line and on-board impact monitoring needs
The results indicate that the accuracy rate decreases when the area of impact monitoring region becomes larger because of the anisotropic propagation of impact signals
Summary
Large scale composite structures have been widely applied in large aircrafts [1,2,3]. Considering the following two aspects, the phase synthesis time reversal impact imaging method is adopted based on some simplifications: (1) only the impact alarm region needs to be localized but not the accurate impact position because the digital monitor can only acquire digital sequences but not impact response signals; (2) for further study, a simple, stable and low power consumption method is more suitable because the whole method needs to be implemented in the FPGA to fulfill the on-line and on-board impact monitoring needs. (2) In Section 3, the impact alarm region imaging and localization method is proposed and the details of the method are studied including the following contexts: (1) the frequency band of the impact response signals is discussed and a frequency band estimation method based on digital sequences is studied; (2) the frequency band of the sinusoidal modulation signals is analyzed. (3) In Section 4, an experiment is implemented on the composite wing of a real aircraft to validate the performance of the method
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
