【作者】 付仁；

【导师】 康国政； 阚前华；

【作者基本信息】 西南交通大学 ， 固体力学， 2013， 硕士

【摘要】 核动力工程压力管道的热棘轮边界问题近年来深受国内外学者和工程界关注。各国规范均给出了热棘轮边界明确的校核要求,但是由于它们自身的局限性,不能适用于复杂的载荷和结构。因此,分析各国规范热棘轮边界的局限性和Bree图的适用性,进而对Bree图中的热棘轮边界进行适当修正是十分必要的。该项工作对于提高核动力工程压力管道设计的安全性,有着重要的参考价值。根据上述研究现状,本论文主要开展如下工作：1.Bree图的有限元验证验证了通过安定的定义、塑性应变增量与机械应力的线性关系和C-TDF规范中等效塑性应变增量法能够很好地模拟Bree图的不同分区的边界。2.热棘轮边界的影响因素(1)理想弹塑性本构模型模拟的热棘轮边界最为保守,多线性本构模型模拟的结果处于上限；根据Bree图热棘轮边界的方程式,分别基于Chaboche模型、多线性模型和Abdel-Karim-Ohno模型提出了修正的热棘轮边界；(2)压力管道壁厚和径厚比对热棘轮边界的影响不大；(3)承受常内压和循环温度载荷的薄壁圆筒在拉伸应力作用下,随着轴向载荷的增加,热棘轮边界上移；压缩应力作用下,随着轴向压应力的增加,热棘轮边界趋于保守；根据轴向载荷作用方式的不同,提出了修正的热棘轮边界。3.管道过渡段热棘轮边界的包络线基于理想弹塑性本构模型和Abdel-Karim-Ohno模型,模拟了管道过渡段的热棘轮边界,进而根据Bree图热棘轮边界的函数式,提出了涵盖不同过渡段尺寸模拟的热棘轮边界的包络线。更多还原

【Abstract】 Thermal ratcheting boundary of pressure pipeline in nuclear power engineering is popular topic to researchers and engineering recently. The requirement for checking the thermal ratcheting boundary was specified by many national codes. However, they are not suitable for the complex loadings and structures due to their limitation. Therefore, it is necessary to improve the existed thermal ratcheting boundaries by analyzing their limitation and applicability. This study has an important theoretical significance for improving the structural design of the nuclear power engineering.According to the state-of-art of thermal ratcheting boundary, the main contexts of this thesis are summarized as below:1. Validation of Bree’s diagram by finite element methodIt is demonstrated that Bree’s diagram can be simulated reasonably by combining the definition of shakedown, the linear relationship between the plastic strain increment and mechanical stress and the method of equivalent plastic strain increment from C-TDF codes.2. Influence factors of the thermal ratcheting boundary(1) The thermal ratcheting boundary simulated by elastic perfectly-plastic model is most conservative and the result by multilinear model is the upper bound. The modified thermal ratcheting boundaries are proposed on the base of Chaboche, multilinear and Abdel-Karim-Ohno models respectively.(2) The influence of wall thickness and ratio of radius to thickness of pressure piping on the thermal ratcheting boundary is very small.(3) The thermal ratcheting boundary is more conservative with a decreasing axial load for thin-walled tubular subjected to cyclic temperature, internal pressure and axial tensile stress. However, the thermal ratcheting boundary is more conservative with an increasing axial compression stress. The modified thermal ratcheting boundary is proposed based on the different axial loads.3. Envelope curves of the thermal ratcheting boundary of transition in pipeThe thermal ratcheting boundary of transition in pipe is investigated on the base of the elastic perfectly-plastic and Abdel-Karim-Ohno models. And then, the envelope curves of the thermal ratcheting boundary are proposed by using Bree’s diagram, which covers different sizes of transition.更多还原