Active infrared thermography in non-destructive evaluation of surface corrosion 2: heat exchange between specimen and environment

A thin plate ? has an inaccessible side in contact with aggressive external agents. On the other side we are able to heat the plate and take temperature maps (thermal data) in laboratory conditions. Detecting and evaluating damages on the inaccessible side from thermal data requires the solution of a nonlinear inverse problem for the heat equation. To do this, it is extremely important to assign correct boundary conditions, in particular on the inaccessible boundary of ?. In several cases the boundary conditions must take account of heat exchange between ? and the environment. Here we discuss, from the quantitative point of view, the relation between the physical constants of the system (conductivity, width of the plate, ...) and the heat transfer through the boundary of ?.