Finite element modeling of the temperature rise due to the propagation of ultrasonic waves in viscoelastic materials and experimental validation

摘要

The ultrasound stimulated thermography method is usually used to detect the temperature rise at a defect position. The temperature rise can be due to the friction between the edges of the defect and/or the plastic deformation around the defect. This paper presents another aspect of the method when the ultrasounds are propagating in a viscoelastic anisotropic material, such as polymers or fiber-reinforced polymers. The attenuation of the waves produces a distributed temperature field. Therefore, even a defect that does not produce some heat can be detected, the ultrasonic field is modified. A finite element model is used for computing the temperature field and for predicting the possibility for an infrared camera of detecting the temperature rise and its modification due to a defect. The model computes the stress and displacement fields associated with the propagation and the loss of energy. Then the heat equation is solved with this loss as a source of heating. An experiment is done with a sonotrode that excites a PVC plate. The ultrasonic displacement at the top of the plate is measured with a laser velocimeter and introduced in the model. Finally, the model result is compared to the image produced by the camera. (C) 2008 Acoustical Society of America. [DOI: 10.1121/1.2998392]