Infrared Delamination Defect Detection of Type III Aluminium Lined Gas Cylinder

Abstract

In this study, the influence of two thermal loading methods, internal excitation and external excitation, on the defect detection effect is systematically investigated for the difficult problem of detecting delamination defects in carbon fibre-wound gas cylinders with aluminium inner liner of type III. By establishing an axisymmetric two-dimensional model of the gas cylinder, the heat conduction process under different defect parameters (length, thickness and depth) was simulated, and the multi-parameter coupling effect was analysed by using orthogonal tests. The results show that the external thermal excitation method is significantly better than the internal excitation in terms of detection sensitivity, temperature difference contrast and time resolution, and the optimal detection time window is 45-90 seconds. The peak thermal image temperature difference increases approximately linearly with the defect length, and its growth rate increases with the defect thickness and tends to stabilise, and the defect depth increases, resulting in a gradual decrease in the peak thermal image temperature difference and a slower decrease in the magnitude of the peak temperature difference; on the analysis of the significance of the defect parameters, the depth of the defects has the most significant effect on the temperature difference (contribution rate of 53.7%), followed by the length of the defects (contribution rate of 19.2%), and the defect thickness has a smaller effect (contribution rate of 6.5%). 6.5%). This study provides a theoretical basis and optimisation scheme for the non-destructive testing of delamination defects in type III gas cylinders.