Hosten B, Bacon C, Biateau C
Laboratoire de Mécanique Physique, Université de Bordeaux, UMR CNRS 5469 351, Cours de la Libération, Talence Cedex, France.
J Acoust Soc Am. 2008 Dec;124(6):3491-6. doi: 10.1121/1.2998392.
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.
超声激发热成像方法通常用于检测缺陷位置处的温度升高。温度升高可能是由于缺陷边缘之间的摩擦和/或缺陷周围的塑性变形。本文介绍了该方法的另一个方面，即超声波在粘弹性各向异性材料（如聚合物或纤维增强聚合物）中传播时的情况。波的衰减会产生一个分布式温度场。因此，即使是不产生热量的缺陷也能被检测到，因为超声场会被改变。使用有限元模型来计算温度场，并预测红外热像仪检测由于缺陷导致的温度升高及其变化的可能性。该模型计算与波的传播和能量损失相关的应力和位移场。然后，以这种能量损失作为热源来求解热方程。使用一个激励PVC板的超声焊极进行了一项实验。用激光测速仪测量板顶部的超声位移，并将其引入模型。最后，将模型结果与热像仪生成的图像进行比较。
