Study of Debonding Detection of Thermal Protection Structure Based on Distributed Optical Temperature Sensing

本文研究了基于金属结构基体表面温度场在极短时间内的变化情况推断热防护结构的脱粘事件。分别采用有限元计算方法和基于光频域反射(OFDR)解调的瑞利散射分布式光纤传感技术，对外界环境温度、热防护结构脱粘面积和脱粘厚度等可变因素下的金属结构基体表面温度场变化展开评价，进而总结其内在联系。通过高空间分辨率的热力学仿真及光纤测量数据能够表明：外界温度越高、热防护结构脱粘面积越大、脱粘厚度越大，金属结构基体表面温度短时间内上升得越高，且通过温度场梯度变化能够对热防护结构脱粘面积进行较精确的估计。This study investigates the inference of debonding events in thermal protection structures based on transient changes in the surface temperature field of a metallic substrate. Both finite element simulation and Rayleigh backscatter distributed optical fiber sensing technology, demodulated using Optical Frequency Domain Reflectometry (OFDR), were employed to evaluate variations in the substrate surface temperature field under variable factors, including ambient temperature, debonded area, and debond thickness. Subsequently, the intrinsic relationships were elucidated. High-spatial-resolution thermodynamic simulations and optical fiber measurement data demonstrate that: The higher the ambient temperature, the larger the debonded area, and the greater the debond thickness, the more pronounced the transient temperature rise on the metallic substrate surface. Furthermore, analysis of the thermal gradient enables a relatively precise estimation of the debonded area within the thermal protection structure.