A Research Of Wind Turbine Blade Delamination Testing Technology Based On The Acoustic Impact

Non-destructive testing for wind power generation equipment is an effective means to extend itslife and reduce its maintenance costs. It became extremely important to discover the existence of theblade damage during the life of the blade, especially delamination early.This paper first introduced the types of delamination in various stages of blades’ life cycle andsummarized non-destructive testing method for detecting composite material at home and abroad.Then, the theoretical model of acoustic impact was analysized in detail, and the characteristicparameters of delamination defect information were established as basises for the design ofinstrumentation.The paper discussed the working principle of FPGA-based wind turbine blade delaminationdetector. Through tapping the blade, the instrument analysis characteristics of the stress signal inhammer. When delaminates were appeared, the stiffness of defects was decreased and the duration oftap stress was increased.To produce the instrument includes three parts: tap hammer manufacture, hardware design andsoftware design. Considering its material properties and quality requirements the hammer chose nylonhead, steel body structure. The piezoelectric film sensor was embedded in the hammer head section.Hardware design consists of impedance matching circuit, polarity reversal circuit and filter amplifiercircuit. The final signal was input digital signal processing module and analog signal processingmodule separately. The software part of core device Altera’s FPGA includes two aspects, one is thedigital logic module for the duration of the stress signal, which can be used as a peripheral componentfor the follow-SOPC system; the second is SOPC system, which is aimed to collect, analysis, display,communication data.Finally, the standard specimen and actual damaged wind turbine blades were studied by thedeveloped instrument. Experimental data showed that this instrument has good performance indetecting the thin layer delamination, and detection path could be planned based on the trend of testresults.