第1部分:SS-316结构的双轴热机械疲劳响应:SS-316型等温和热机械疲劳寿命评估加压设备的设计涉及多种复杂载荷组合的考虑。涉及结构疲劳的循环荷载是最复杂的工程问题之一。本项目的目的是为设计工程师提供一种方法，以解决高温下双轴疲劳问题的复杂性，其中载荷既有机械载荷，也有热载荷，且它们之间的相位关系在- 相位到相位差。该项目还展示了进行双轴热机械疲劳（TMF）测试的能力。典型的疲劳数据是在恒温（等温）和单轴条件下进行的。然而，典型的反应器、压力容器、管道或其他结构部件可能会受到复杂的热和机械瞬态载荷条件的影响，具有各种各样的相位关系。本项目的目标是为设计工程师提供解决这些问题的工具。第2部分:不锈钢的双轴热机械疲劳响应- 316结构:双轴效应扩展结构热机械疲劳响应的表征双轴热机械疲劳（TMF）模型是通过扩展等温条件下的双轴疲劳模型开发的。提出的模型评估了同相和异相循环，考虑了氧化和蠕变的影响。等温疲劳模型采用了三轴系数（TF）的概念，它解释了应力状态对材料断裂韧性的影响。在399的循环温度下，TMF双轴应变比在0到3.65之间变化- 621摄氏度（750-1150华氏度）。所有试验均采用管状试样进行应变控制。加热采用感应方式，冷却采用自然对流方式。

Part 1: Biaxial Thermo-Mechanical Fatigue Response of SS-316 Structures: Isothermal & Thermo-Mechanical Fatigue Life Assessment for Type SS 316The design of pressurized equipment involves consideration of a wide range of complex load combinations. Cyclic loading involving fatigue of structures is one of the most complex engineering issues. The purpose of this project is to provide the design engineer with a methodology for addressing the complexity of biaxial fatigue problems at elevated temperature where the loading is both mechanical and thermal and the phase relationship between them varies from in-phase to out-of-phase. The project also demonstrates the ability to perform biaxial thermo-mechanical fatigue (TMF) testing.Typical fatigue data was performed at a constant temperature (isothermal) and under uniaxial conditions. However, typical reactors, pressure vessels, piping or other structural components may be subjected to complex thermal and mechanical transient loading conditions with a wide variety of phase relationships. The objective of this project is to provide the design engineer with a tool for addressing these issues.Part 2: Biaxial Thermo-Mechanical Fatigue Response of SS-316 Structures: Characterization of Thermo-Mechanical Fatigue Response of Structures Extended for Biaxiality EffectA biaxial thermo-mechanical fatigue (TMF) model has been developed by extending a biaxial fatigue model for isothermal condition. The proposed model assesses the in-phase and out-of-phase type cycle incorporating the effect of oxidation and creep. The isothermal fatigue model utilizes the concept of triaxiality factor (TF) which accounts for the state of stress effect on material's fracture ductility. The TMF biaxial strain ratios varied from 0 to 3.65 at cyclic temperature of 399-621°C (750-1150°F). All tests were strain controlled using tubular specimens. Heating was by induction and the cooling was by natural convection.