Research On Damage Identification And Location Of Composite Laminates Structure Based On Lamb Wave

The damage of composite materials is a serious threat to aviation safety.Therefore,it is necessary to develop a detection method and technology that can quickly identify structural damage in composite materials.Lamb wave signal has many advantages such as small attenuation amplitude and more sensitivity to suitable damages,and is suitable for damage detection of large-area composite materials.Taking carbon fiber composite laminates as the research object,the location and identification of the hole damage in the carbon fiber composite material plate are studied through the finite element method and experiment.A damage probability method based on Lamb waves is proposed in this paper,which is used to locate and identify damage in composite laminates.According to the three-dimensional elastic theory and the global matrix method,the dispersion equation of Lamb wave propagation in composite laminates is derived,and the dispersion curves and the variation curves of wave velocity with the propagation angle are drawn.The influence of propagation distance and propagation angle on Lamb wave propagation in composite laminates is studied.The global time difference relationship is established by the time difference method,and the global damage probability map of the laminate can be obtained by matching the actual time difference with the global time difference.The healthy and damaged carbon fiber composite laminate model was established for numerical simulation by ANSYS finite element analysis software.There is a 10 mm diameter hole damage in the damaged model.The Lamb wave signal is generated by applying a modulated 5-peak sine signal on the piezoelectric sheet(PZT).The damage reflection signal of the Lamb wave in the carbon fiber composite laminates is analyzed by Wigner Ville Distribution(WVD),and the arrival time of the damage reflection signal is extracted.The location accuracy of the damage center increased by 46% through excitating each PZT.The identification of the damage area is realized by selecting the point where the probability of damage is greater than or equal to 0.99.The damage location and recognition effect of the damage probability method on the damage of the hole with a diameter of 5mm is studied.The applicability and accuracy of the damage probability method for the damage location and identification of the carbon fiber composite laminate structure are preliminarily verifiedThe experimental damage detection platform is built by arbitrary waveform generators,oscilloscopes and other equipments.The test piece used in the experiment is a carbon fiber composite laminate,and a drill hole with a radius of 5 mm was prefabricated.The excitation signal is generated through an arbitrary function generator,and the Lamb signal is detected with an oscilloscope.The accurate arrival time of the damage reflection signal is extracted by WVD.The location of the damage center and the identification of the damage area are realized by the damage existence probability method.The effectiveness of the location and identification of the damage in composite laminates by the damage existence probability method is further demonstrated.