Abstract: The differential equation of heat energy wave transmission expresses the unbalanced state of heat in the heat energy wave transmission formed by the modulation infrared pulse wave injected into an insulation as well as expresses the relationship between the thermal diffusion coefficient, medium consistency and mechanical performance. It furnishes the medium information heat transmission theory within the insulation and its calculation method. Dynamic response can determine the temperature distribution of the insulation and the flaw. Measuring the swings and phases of radiation signals under different modulation frequencies and increasing the peak value of heat energy waves can find corresponding parameter values and determine the place, thickness, heat conductance and thermal diffusion coefficient of a flaw. The technique is especially applicable to complex material, surface coating or plating to detect the inanition or cracks of different insulations.

Key words: modulation infrared pulse wave, differential equation, dynamic response, insulation within flaw