Development of Simulation Software for the Evaluation of Small Defects to Build a Remaining Life Assessment if High-Temperature Structures

在本研究中，新开发了一套用于预测燃煤电厂锅炉、汽轮机等高温部件剩余寿命的系统及其软件。所得结果总结如下：1。为了预测蠕变疲劳小裂纹的萌生和扩展行为，采用晶界随机断裂抗力模型进行了数值模拟。一种基于仿真结果的构件剩余寿命估算系统。一种确定仿真条件的逆方法，即。从小裂纹的实际分布出发，给出了断裂驱动力。这种逆方法使我们能够将仿真引入剩余寿命预测系统。将该方法应用于规定条件下的结果，证明了该方法的有效性。即使在行驶过程中驱动力突然变化的情况下，该方法仍然有效。为了验证该系统的适用性，对高温合金在多轴载荷作用下的裂纹进行了数值模拟研究。本课题还对损伤力学和蠕变分析进行了基础研究。

In this research, a system and its software were newly developed for predicting remaining life of such high-temperature components as boilers and turbines, which comprise a fossil power plant. Results obtained here are summarized as follows :1. To predict the initiation and propagation behavior of small creep-fatigue cracks, numerical simulation was carried out using a model of random fracture resistance of grain boundaries. A new system estimates components remaining lives based on the simulation results.2. An inverse method of determining the simulation conditions, uiz. fracture driving force, from the actual distribution of small cracks was presented. This inverse method enabled us to introduce the simulation into the remaining life prediction system.3. The validity of the inverse method was proved by applying this to the results for prescribed conditions. The method was valid even when driving force changed abruptly on the way.4. To examine the applicability of the present system, numerical simulation for cracks under multi-axial loading or the on for cracks on a superalloy were investigated. Damage mechanics and creep deformation analysis were also discussed as a fundamental study in this research project.