Abstract
Recently, the influence of heat conduction has been considered to be a big problem. Hence, the system is developed which corrects an error in the images of the sum of the principal stresses by inverse analysis taking into consideration the influence of the heat conduction. Then, the influence of heat conduction was investigated by the experiment which changed the material, thickness of the specimen and frequency of experiment, hi the case of the analyses of the material of the low heat conductivity, even if it does not take the influence of heat conduction into consideration, a highly precise stress analysis is possible. The stress analyses obtained by infrared thermography at low frequency cyclic load have a large error in metals with high heat conductivity. However, the influence of the heat conduction included in the infrared stress images obtained at high frequency cyclic load can be modified by the inverse analysis of non-steady heat conduction. In this study, we investigated the acrylic resin specimens of the viscoelastic material which is influenced greatly by a frequency change. The optimal frequency for exact principal stresses separation was examined changing the frequency with 4 to 30 Hz by the comparison with the 3-D finite element method. It was found that the optimum frequency of the cyclic load of acrylics material is from 6 Hz to 10 Hz. Moreover, the validity of this approach was discussed paying attention to the hysteretic characteristics as seen in viscoelastic materials, such as acrylic material.
