Infrared Ct Imaging Nondestructive Testing Research

Infrared tomography nondestructive testing has many advantages, such as quickness, non-contact, large detection area, no harmful radiation and so on, which can map the internal characteristics of the object by means of heat conduction model. Since most objects have thermal conductivity, this method is widely used in nondestructive testing field.In order to get materials’ internal defect information, this topics studies infrared tomography nondestructive testing on materials. Firstly, this paper introduces its research background and development, and then establishes nondestructive testing model based on the principle of heat transfer, which is solved by the finite element method. Secondly, composite coefficient conjugate gradient algorithm is raised, which is used to solve the inverse problem of heat conduction model, to map materials’ internal defect information. Thirdly, a hardware and software system constructed can increase the interaction between the user and the program, and can more easily obtain nondestructive testing image and internal defect information. Finally, the experiment and ANSYS simulation are used to obtain the temperature distribution on the outer surface of the test piece of materials, which have different defect depth and thermal conductivity. A reasonable objective function is created, and then conjugate gradient method is used to optimize it. The experimental and simulation results verify the feasibility of the algorithm, and can achieve the purpose of infrared tomography nondestructive testing. Study shows that the depth of subsurface defect and thermal conductivity of material are important factors, which affect the accuracy of the defect detection. The smaller the depth of the defect from the surface is, the higher defect detection accuracy. With the increase of thermal conductivity, the internal heat transmits faster, and spread the defect parts faster. When a momentary steady-state is reached, defect detection accuracy increases at first and then decreases. This method can obtain more accurate information on the location and the size of the defect in the material, providing an assistant way for infrared tomography nondestructive testing.