低温环境下光纤光栅传感器的抗疲劳设计

项目名称： 低温环境下光纤光栅传感器的抗疲劳设计

项目编号： No.51505150

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 机械、仪表工业

项目作者： 徒芸

作者单位： 华东理工大学

项目金额： 20万元

中文摘要： 面向保障重大机械产品服役安全的需求，针对低温下缺乏可靠传感装置的问题，开展低温下光纤光栅传感器疲劳失效机理及抗疲劳设计的研究。包括：（1）研究裸FBG在低温-循环应变共同作用下光学特征量退化规律，揭示循环温度幅对热疲劳寿命以及温度对机械疲劳寿命的影响规律，建立考虑温度效应的疲劳寿命模型；（2）研究FBG温度/应变传感器在低温-循环应变共同作用下光学特征量退化规律，厘清低温下涂层/封装的材料/结构/工艺参数及界面结合性能对疲劳寿命的影响规律，建立包含温度效应、涂层/封装效应及界面效应的疲劳寿命模型；（3）基于微观分析，揭示裸FBG和FBG传感器的疲劳失效机理及光学性能退化机制，建立光学性能退化特征量与含疲劳损伤光栅内非均匀应力/应变分布的映射关系，提出考虑低温下疲劳性能及其对光学性能影响的耐低温光纤光栅传感器抗疲劳设计方法。本研究将为高可靠长寿命耐低温光纤光栅传感器的设计制造提供基础理论支撑。

中文关键词： 光纤光栅传感器；低温；结构完整性监测；循环应变；疲劳寿命

英文摘要： The increasing concerns on energy and environment call for modern plant operating under extreme environments. It is thus important to ensure the safety of critical industrial equipment. However, reliable sensors to measure temperature and deformation at cryogenic temperatures have been a long standing challenge. In this research project, fatigue failure mechanisms and fatigue design of fiber Bragg grating (FBG) sensors at cryogenic temperatures will be investigated. Main contents are as follows: (1) The degradation of the optical characteristics of bare FBGs is obtained under strain cycling at cryogenic temperatures. The effect of temperature amplitude on the thermal fatigue life of bare FBGs is demonstrated, as well as the effect of temperature on the mechanical fatigue life. The prediction models are proposed to account for the temperature effect on the thermal and mechanical fatigue life of bare FBGs, respectively. (2) The degradation of the optical characteristics of FBG temperature/strain sensors is also obtained under strain cycling at cryogenic temperatures. The effects of materials, thickness and process parameters of coating, as well as interfacial bonding characteristics between coating and optical fiber, on the thermal fatigue life of FBG temperature sensors are presented. And the effects of materials, structural parameters and process parameters of packaging, as well as interfacial bonding characteristics between coating and optical fiber, on the mechanical fatigue life of FBG strain sensors are demonstrated. The prediction models are proposed to account for the effects of temperature, coating/package characteristics and interfacial bonding characteristics on the fatigue life of FBG temperature/strain sensors, respectively. (3) Mechanisms of fatigue failure and optical degradation of the bare FBGs and FBG sensors are demonstrated based on microscopic analysis. The relationship between the degraded optical characteristics and the stress/strain distribution in damaged fibers is established. The fatigue design method of FBG sensors is therefore proposed to account for the fatigue properties and their effects on the optical properties at cryogenic temperatures. This basic research thus could provide the fundamental theories and concepts for design and manufacturing of long-term reliable and durable FBG sensors at cryogenic temperatures.

英文关键词： fiber Bragg grating (FBG) sensor;cryogenic temperature;structural integrity monitoring;cyclic strain;fatigue life