The Study Of Finite-element Modeling Of Defect Size Measuring For Pulsed Thermography Measurement

Infrared thermal wave non-destructive testing technology is developing rapidly in recent years, there are a wide range of applications in aerospace and machinery manufacturing. According to the subject matter of the material properties and defects of different types, thermal wave non-destructive testing uses different for heating the surface. The heat inside the object is passed down, Because of the defects, the corresponding surface temperature of defect region and non-defective region are different. Then, the thermal imager recorded surface temperature field changes with time. By infrared radiation and material science knowledge to establish contact between thermal excitation source and materials, getting various defects information were seized on the surface or internal and heat transfer law under the boundary conditions, establishing the inner link between the distribution of the surface temperature field and the defect. The change and distribution of material surface temperature field can analyze the defect depth, shape and size of the detected object. At last, we can realize the quantitative calculation of the material size and depth. There are many restrictions in the experiments, such as environmental impact, these factors cannot be solved can be done with the help of simulation, establish a heat conduction model, and simulate the infrared NDT testing process. Using the same method for experiments to get the inside information of the model and calculating the defect size under the ideal condition.ANSYS software is currently one of the more popular large-scale finite element analysis software, can solve the multidisciplinary analysis of the problem, such as:structure, mechanics, thermodynamics, fluid, electromagnetic field and between any two or more physical field coupling problem. Thermal analysis module is mainly used in this thesis. It can analyze various thermodynamic problems in the experiment.Infrared thermal imaging non-destructive testing, quantitative calculations and research of the defect under the surface, using ANSYS finite element software simulation to do the simulation test. Extracting the cloud model of the surface temperature to calculate the internal information, it becomes a reference for the actual testing and provides a basis for optimizing the actual detection.This paper briefly introduces the basic theory of infrared thermal imaging technology, basic principle of ANSYS finite element software and function and application of thermal analysis module. Test the defects of the three different material specimens, the Aluminum flat-bottomed holes, stainless steel flat-bottomed holes and fiberglass flat-bottomed holes. And FWHM (the half high width) method as a criterion, respectively for three kinds of defect size calculation. Discussing to find out defects FWHM error and finding the law of the change over time. ANSYS finite element software breakthrough the limitation of experiment can’t reach, especially for the experiment can’t detect information plays a secondary role. Respectively by use of ANSYS software, the above-mentioned three types of heat transfer rate is large specimen for simulation of infrared thermal wave non-destructive testing. With FWHM method calculating the defect size by using ANSYS software simulation of infrared thermal wave non-destructive testing. Compared with infrared thermal imaging experimental results, show that the finite element software ANSYS can defect quantitative measurement of infrared thermal wave non-destructive testing, and in a sense can be the result of the experiment to supplement and explanation, provides reference for pulse infrared thermal image inspection.