Analysis of Influence Factors in Step Heating Thermography to Composite Materials

In process of Thermal Wave NDT, as a result of influence from kinds of factors, such as noise, intensity of heating signal, defect dimension, it is very difficult to get good testing data. In order to resolve it, the method of numerical computing was taken to simulate the process of heat conduction in sample. At the simulating process, some valuable phenomenon were found, and as follows: When time of heating time was enough, temperature changing at surface would be steady, and rate of changes could be approximately considered as a constant; the biggest contrast would delay, as depth and diameter increased; the greater intensity of heating signal was, the quicker change of contrast was; and it was more important to ascertain the best testing time when the biggest contrast occurred. And these were valuable to acquire more precise testing result.