Thermal Elastic-Plastic Analysis Considering Temperature Rise by Rapid Plastic Deformation in Undermatched Joints

The characteristics of dynamic strength and fracture in structural steels and their welded joints particularly for pipelines should be evaluated based on the effects of the strain rate and service temperature. The temperature, however, rises so rapidly in structures due to the plastic work under the high strain rate such as ground sliding by earthquake when the effect of the temperature cannot be negligible for the dynamic fracture. It is difficult to predict or measure the temperature rise history with the corresponding stress-strain behavior, including the region beyond the uniform elongation, though the behavior at the large strain region after the maximum loading point is very important for the evaluation of fracture. In this paper, the coupling phenomena of the temperature and stress-strain fields under dynamic loading were simulated by using the finite element method. A modified rate-temperature parameter was defined by accounting for the effect of the temperature rise under rapid plastic deformation, and it was applied to the fully coupled analysis between the heat conduction and thermal elastic-plastic behavior. The temperature rise and stress-strain behavior, including the coupling phenomena, were studied including the region beyond the maximum loading point in structural steels and their undermatched joints, and then compared with the measured values.