Ultrasonic Testing And Evaluation Of RTM Carbon Fiber Composite Defects

RTM carbon fiber composite material with its superior performance,lower cost,in recent years in aviation,aerospace,automobile manufacturing,sports and many other areas have been valued and widely used.However,due to its production process,the environment and other factors,the final shape of the material may have some defects,including two categories calling macro-defects and micro-defects,these defects greatly affect the material's performance.Therefore,it is very important to study the detection and evaluation of the material defects.In this paper,based on the study of RTM carbon fiber composite defects on the basis of the use of ultrasonic feature scanning imaging detection method with the test of non-linear detection of macroscopic defects and pore microscopic defects were evaluated.By analyzing the images formed by ultrasonic detection with defects,the macroscopic defects of various macroscopic defects were summarized,and the method of nonlinear micro-defect detection was optimized.The main work is as follows:(1)Theoretically studied the ultrasonic waveforms and ultrasonic characteristic scanning images corresponding to the macroscopic defects of RTM carbon fiber composites,and provided the theoretical basis for the identification of different macroscopic defects.The macroscopic defects were detected by the method of ultrasonic feature scanning imaging.The morphological features of various macroscopic defects were analyzed by imaging method,and the defects were analyzed and summerized.Finally,the macroscopic defects are analyzed by metallographic analysis to verify the reliability of the test results.(2)Based on the predecessors,the methods of nonlinear ultrasonic inspection of porosity defects are optimized,including improvement of experimental method,improvement of ultrasonic transducer,selection of excitation voltage,selection of optimal probe frequency,time threshold Selection of waveform interval.The authenticity of the optimization results is verified by a sample with known true porosity.The results show that the characteristics of loose defects,delamination defects,inclusions defects and bubble defects are different from those of defective imaging features,which can be used as the basis for judging different types of defects which is an important reality for the study of macroscopic defects.By optimizing the ultrasonic ultrasonic testing method,ultrasonic transducer selection,excitation voltage selection,probe frequency selection and time-domain waveform interval selection,the stability of the experiment is better and the repeatability is stronger,which makes the representation of the rate more accurately.