Research On The Ultrasonic Testing For Large Composite Components

There are many large composite components made of fiber reinforced resin matrix composites.Due to the large size,self-weight,design versatility of large-scale composite materials,laminated structure commonly used in the design.Because the component is a laminated structure,defects such as delamination and cracks are inevitably generated in the component forming process.Bubbles and inclusions may also exist inside the sandwich material and the composite substrate.It is the important method to ensure the quality of the component that the full-size inspection of the large component.According to the forming process of FRP pipe manufacture,the technology of detecting the FRP pipe defects by ultrasonic wave was studied.The influence of different probe parameters on the sound field distribution of the probe was analyzed.The optimization method for composite structure probes with sand-containing layers was studied.A water jet ultrasonic dual crystal straight probe for detecting the laminated structure of FRP pipe was designed,and a judgment program to detect the FRP defects was developed too.The specific work of this dissertation is as follows:(1)The research status of ultrasonic testing method for large composite materials at home and abroad was reviewed.The research status of ultrasonic sound field calculation model and sound field simulation was summarized.The ultrasonic double crystal probe was designed and the method for calculating the structural parameters of the probe was improved.(2)Optical microscopic observation,compositional and structural analysis,ultrasonic attenuation performance measurement,defect types and size analysis,sound velocity measurement,DR detection and phased array detection were carried out on the FRP composite material.These experiments provide the basis for probe design.(3)The space impulse response calculation model was studied.Based on the Field II sound field simulation software toolkit,the acoustic field simulation calculation model of the dual-crystal probe was proposed.Based on the Matlab GUI toolbox,the dual-crystal sound field simulation graphical user platform can realize the input of simulation parameters and the output of simulation data.Based on the Matlab platform,the sound field distribution of the dual crystal probe under different parameters was simulated and the influence of the probe parameters on the sound field distribution was obtained.According to the distribution of sound field with different crystal sizes,crystal inclination angle and the size of the component,the square crystal size and the crystal inclination angle were determined.An ultrasonic probe was fabricated by using piezoelectric ceramics(PZT)and composite crystal(1-3 composite crystal).The results of the two crystal were compared and analyzed to determine the material of the ultrasonic probe crystal.(4)Design and fabricate an ultrasonic probe continuous coupling medium application structure.The probe designed in this dissertation is used to detect the component.According to the test results of different defects,the calibration methods was determined,such as layered defect echo,traverse hole defect echo,hole defect echo and structural interface echo.The design of an ultrasonic probe for the detection of sand-filled composite component was designed and manufactured,and the method for the flaw detection of flaw echo signals was studied.