Strain-temperature monitoring and decoupling by distributed fiber optic sensors for typical astronautic structures

Aerospace structures, when serving in complex environments with multi-field coupling over the long term, are prone to the effects of extreme temperatures and external forces. However, fiber optic sensors, due to their inherent cross-sensitivity characteristics, struggle to simultaneously monitor temperature and strain. To address this, this paper develops a method for decoupling fiber optic strain and temperature mixed signals based on parameter adaptive time-varying filter empirical mode decomposition. A gray wolf optimization algorithm objective function based on the Pearson correlation coefficient is proposed to adaptively optimize the core parameters of the time-varying filter empirical mode decomposition, such as the bandwidth threshold and B-spline order, thus solving the modal aliasing phenomenon caused by unreasonable parameter settings in traditional empirical mode decomposition algorithms. A method for identifying strain and temperature sensitive components based on multi-dimensional weighted indicators is proposed, achieving synchronous measurement and decoupling of strain and temperature parameters using the same sensing fiber. An experimental system for fiber optic strain and temperature monitoring and decoupling of typical aerospace panel structures was constructed, with a temperature decoupling root mean square error of 0.4℃ and a strain decoupling error of 15με. On this basis, a strain and temperature monitoring and decoupling system for rotating mechanism gear pairs was also built. The research results are applicable to the construction of high-precision multi-parameter synchronous monitoring networks and can provide important technical support for the in-service identification, health assessment, and maintenance decision-making of key aerospace structure states.