Numerical Simulation Of Infrared Nondestructive Testing For Carbon Fiber Composite

Using the large-scale finite element analytic software ANSYS , the transient temperature field of carbon fiber composite, stainless steel 9Cr18 and cast aluminium ZL201 and titanium alloy TC3 were simulated. The defect depth, size and thickness, intensity of heat current, monopulse, multi-second heating on the thermography difference and thermography contract of the carbon fiber composite were calculated and analyzed. The effect of different and defects materials on thermography difference and contrast were analysised. The main results were obtained by computational analysis as follows:(1) When there are some surface defects, bigger defects, thicker defects in the sample, the values of temperature difference and the extreme thermography contrast are larger, the results show that the surface defects, bigger defects and thicker defects are easy to be detected, and have the higher sensitivity.(2) The intensity of heating has changed thermography difference, but which has no effect on the best detection time and thermography contract. The results show that the theoretical detection sensitivity and the best detection time have relative with the heating intensity.(3) The different size and the depth of the air defects in carbon fiber composite materials have been quantitatively analyzed. The results show that the major shortcomings of the surface need the minimum heat flux; in the deeper detection of small defects need the greatest heat flux in the testing. When the heating time is for the 0.05s and the extreme value of surface temperature contract is 0.2℃.(4) The total heat input constantly, the monopulse is studied by changing the heating time and heat flux. The results show that, the shorter heating time and the more sensitivity of heat flux have more beneficial to detect and the theoretical detection sensitivity is higher. The total heat input constantly, by changing the quantity of heat twice and cooling time between two heats. The results show that intermittent heating is not conducive to testing. The distribution and continuity of heat have a great influence on the theoretical detection sensitivity.(5) By changing the sample and defect materials the effect of different materials on thermography difference and thermography contract is calculated. The results show that when the sample is made from cast aluminium ZL201, the defect is easier to be detected and have higher theoretical detection sensitivity; when the sample is made from carbon fiber composite material the defect is more difficult to be detected and have lower theoretical detection sensitivity. The defect is the dry air, the defect is easier to be detected and have higher theoretical detection sensitivity; the defect is the epikote, the defect is more difficult to be detected and have lower theoretical detection sensitivity.