Relationship Between Transient Time-dependent Surface Tempreture Difference And Concrete Defect In Infrared Non-destruction Testing

Infrared thermal image testing can be widely used to evaluate structure's quality and function, but in China the study is at a preliminancy stage and the testing theory of this field is far from complete. So, it is of great significance to study infrared non-destruction testing. In this paper, the experiment and theory study on concrete defect by infrared thermal image testing is one of the main content of National Nature Fund project -quickly detecting the concrete deterioration by infrared remote sensing techniques, which is to discuss the relationship between transient time-dependent surface tempreture difference and concrete defect by means of theory analysis, computer simulation and exprement on the basis of others' research achievements. Details are listed below:1. Different from those one-dimensional models, this paper includes all variables that affect the transient and time-dependent surface tempreture difference, and establishs a three-dimensional thermodynamic similarity model by means of dimension concordant principle and Buckingham theorem. The model can be applied to various material and boundary problem.2. Using the similarity model and finite element method, the variation between transient time-dependent surface tempreture difference and Fournier Number under the boundary of the second and third temperature. Results have shown that the computation results are accordant to experiment.3. Simulating the boundary of actual engineering, the effect of the depth and size of concrete defect to surface tempreture difference is respectively analyzed and the functional relationship is established. On the basis of it, a method is got to detect the depth and size of concrete defect. Considering the action combining the depth with the size, the coupled functional relationship is established. The effect of thickness to surface tempreture difference is also analyzed and the relationship is established. For the convenience of the engineering, the effect is modified and the modified factor is also given.At last, a total function relationship between transient time-dependent surface tempreture difference and concrete defect is established.