Influence Of Bonding Composite Patch Repaired Structure On Lamb Wave Propagation

Because of their high specific stiffness and strength,good corrosion resistance and capability of fatigue resistance,carbon fiber reinforced polymer(CFRP)have been widely used in aerospace industry.Due to the influence of the processing and working environment,composite structure often occurs many defects and damage which would seriously affect the overall performance if the damage is not solved in time.Lots of bonding composite patch repaired structures have been used,but the repaired structures will also be damaged possibly,then the strength of the overall structure would be much more dangerous.This paper studied the influence of bonding composite patch repairing circle hole structures on Lamb wave propagation.First of all,this paper introduced and analyzed the Lamb wave,solved the dispersion equations of aluminate plate and dispersion curves were plotted.Piezoelectric equations of piezoelectric effect and inverse piezoelectric effect were presented,and analyzing the vibration characteristics of piezoelectric transducers with different shapes and polarization direction,appropriate shape of piezoelectric transducer was chosen.Secondly,the structure models including piezoelectric transducers(PZTs)with the piezoelectric and inverse piezoelectric effect,aluminum plate,composite laminate patch and adhesive layer were established by means of ANSYS software.The Lamb wave signal was excited and received in the models,and tests were used to verify the correctness of the model.The metal structure with composite patch was simulated to study the effect of different size and shape patches repairing the 2mm hole on the propagation characteristics.The simulation results of circular,square and rhombus patches show that different shapes have different effects on A0 and S0 wave packets.Rhombus patches of different sizes are also different for A0 and S0 wave packets.Thirdly,based on the graphical compilation platform LABVIEW,the semiautomatic experiment platform was set up.Experimentally analyzing the Lamb wave propagation in aluminate and composite plates with different diameter of circle holes,the influence relationship between circle hole diameter and direct mode amplitude of waveform envelope was obtained.Thereinto,there were 120 mm and 180 mm,two distance schemes of the two piezoelectric transducers bonded on the surface of composite plate.Finally,single faced and double faced repairing 10 mm hole of aluminum plate and composite plate were conducted,analyzing Lamb wave response signals,it is concluded that the patch on the other side and the same side of the transducer has larger different influence on wave envelopes of direct modes in the composite plate,providing the basis to test patch structure with Lamb wave.