Abstract: In order to inspect cracks of heavy aluminum alloy structures and to optimize the test conditions, the model of vibrothermography (VT) is presented, and the test conditions and factors are studied by analysis method. The effectiveness of VT for crack inspection is illustrated with an experiment, and then the modeling and calculation of VT are implemented based on the theory of forced vibration and transient heat conduction. The function of the surface temperature increase at the crack area versus the mechanics parameters such as the crack damp, force amplitude, excitation frequency and duration, crack depth, etc. is obtained. The results show that the theoretical data are consistent with the experimental phenomenon, and the influence of various mechanics paramerters on VT can be exactly described by the analytical model presented. The study on the principles of heat generation in VT by the modeling and analysis method has universal significance to reveal the intrinsic mechanism and set up standard windows of operation parameters of VT.

Key words: aluminum alloy, cracks, modeling, nondestructive testing, vibrothermography