Background Temperature gradients significantly affect the material fatigue process. A reliable and robust test procedure is needed for quantifying the effects of temperature gradients on the evolution of fatigue damage in nickel-based superalloys. Objective The present study aims to develop a radiation heating system for universal material testing machine for simulating thermal gradient mechanical fatigue in turbines. Methods The developed heating system mainly consists of halogen lamps, reflectors, cooling subsystems, and control units. Based on extensive experimental and computational investigations, a thermal model is developed for accurate thermo-mechanical fatigue testing under given temperature gradients in the heating system, and it is applied to variable temperature fatigue tests. The detail procedure for determining heat transfer coefficients is presented based on experimental and computational results. Results TGMF tests are successfully performed with the developed radiation heating system. The temperature gradients are found to reduce the TGMF life significantly in comparison to that of the TMF life. Conclusions It is confirmed that the developed thermal gradient mechanical fatigue methodology can be applied to different thermo-mechanical fatigue tests with various temperature gradients.

中文翻译：

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镍基高温合金热梯度机械疲劳试验方法研究

背景 温度梯度显着影响材料疲劳过程。需要一个可靠和稳健的测试程序来量化温度梯度对镍基高温合金疲劳损伤演变的影响。目的本研究旨在开发一种用于模拟涡轮机热梯度机械疲劳的万能材料试验机辐射加热系统。方法开发的加热系统主要由卤素灯、反射器、冷却子系统和控制单元组成。基于广泛的实验和计算研究，开发了一种热模型，用于在加热系统中给定温度梯度下进行精确的热机械疲劳测试，并将其应用于变温疲劳测试。确定传热系数的详细程序是根据实验和计算结果提出的。结果 TGMF 测试通过开发的辐射加热系统成功进行。发现与 TMF 寿命相比，温度梯度显着降低了 TGMF 寿命。结论 已证实，所开发的热梯度机械疲劳方法可应用于具有各种温度梯度的不同热机械疲劳试验。