Abstract It is important to discriminate between mechanical strain and thermal output (apparent strain) in fiber Bragg grating (FBG) strain sensors, due to their sensitivity to both mechanical strain and thermal output. Additionally, when FBG sensors are directly bonded on monitored structures, the transverse effect and the strain-transfer error must be considered to correctly measure the strain. The objectives of this study are to develop pre-tension packaged FBG strain sensors with temperature compensation for use in cryogenic environments and to clarify the performance of the developed sensors in the range from room temperature to 4 K. A developed FBG sensor comprises sensor mounting parts and two FBG that are placed in a row on a single fiber. The one of the FBGs is a strain sensor and the other is a temperature compensation sensor. The developed FBG sensor intrinsically prevents both the transverse effect and the strain transfer error. Experimental investigations are conducted to clarify the performance in the temperature range from room temperature to 4 K for the developed FBG strain sensors. Results confirm that the developed FBG strain sensor demonstrates superior gauge factor stability and a reasonable temperature compensation function. Moreover, the compressive fatigue strength of the developed FBG strain sensor is investigated due to its importance in cryogenic structures that are subjected to cyclic compressive deformations by the repeated operation of cooling and warming processes.

中文翻译：

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用于低温结构测量的温度补偿光纤布拉格光栅应变传感器的研制

摘要 由于光纤布拉格光栅 (FBG) 应变传感器对机械应变和热输出都很敏感，因此区分机械应变和热输出（表观应变）非常重要。此外，当 FBG 传感器直接粘合在受监控结构上时，必须考虑横向效应和应变传递误差才能正确测量应变。本研究的目的是开发用于低温环境的具有温度补偿的预张力封装 FBG 应变传感器，并阐明所开发传感器在室温至 4 K 范围内的性能。开发的 FBG 传感器包括传感器安装部件和两个 FBG 并排放置在一根光纤上。FBG 中的一个是应变传感器，另一个是温度补偿传感器。开发的 FBG 传感器本质上可以防止横向效应和应变传递误差。进行实验研究以阐明开发的 FBG 应变传感器在从室温到 4 K 的温度范围内的性能。结果证实，开发的 FBG 应变传感器表现出卓越的应变系数稳定性和合理的温度补偿功能。此外，研究了开发的 FBG 应变传感器的压缩疲劳强度，因为它在低温结构中很重要，低温结构通过反复的冷却和升温过程而受到循环压缩变形。进行实验研究以阐明开发的 FBG 应变传感器在从室温到 4 K 的温度范围内的性能。结果证实，开发的 FBG 应变传感器表现出卓越的应变系数稳定性和合理的温度补偿功能。此外，研究了开发的 FBG 应变传感器的压缩疲劳强度，因为它在低温结构中很重要，低温结构通过反复的冷却和升温过程而受到循环压缩变形。进行实验研究以阐明开发的 FBG 应变传感器在从室温到 4 K 的温度范围内的性能。结果证实，开发的 FBG 应变传感器表现出优异的应变系数稳定性和合理的温度补偿功能。此外，研究了开发的 FBG 应变传感器的压缩疲劳强度，因为它在低温结构中很重要，低温结构通过反复的冷却和升温过程而受到循环压缩变形。