Study On The Distribution Detection Of Fiber Bragg Grating With Deformation Of Thin-plate Structure

The thin-plate structures are widely used in aerospace,shipbuilding,automobile and other industries.The aircraft wing,satellite solar panel,ship deck,aircraft engine casing,rocket propeller housing are all thin-plate structures.The deformation detection technology of thin-plate structures is one of the key technologies for health monitoring and fault diagnosis of various types of advanced mechanical equipment,with wide engineering application prospect.At present,the strain detection and deformation reconstruction of thin-plate structure based on fiber grating sensing technology is one of the most important research directions in this field.In order to meet the technical requirements of real-time sensing and reconstruction of thin-plate structure deformation,a strain amplification sensor based on fiber Bragg grating was designed first to realize the strain detection for thin-plate structure in this paper.Then,the deformation reconstruction algorithm of thin-plate structure was deduced based on the distributed strain information.Finally the deformation detection system of thin-plate structure based on strain-deformation principle was established.The main contributions of the dissertation are as following:(1)In order to solve the problem that the traditional FBG strain sensors can not meet the requirement of high strain measurement accuracy in thin-plate structure deformation reconstruction,a novel FBG strain sensor based on lever sensitization structure was designed through the analysis of the mechanism of FBG strain transfer.The sensing characteristics of the designed sensor were studied theoretically and experimentally.The results showed that the strain sensitivity of designed sensor is 5~6 times higher than the conventional bare FBG sensor.The strain measurement precision and stability of the developed sensor are better than the bare FBG strain sensor,which can meet the strain detection requirements in the deformation process of thin-plate structures.(2)According to the structural and deformation characteristics of thin-plate structure,based on the theory of elastic mechanics and finite element analysis method,the mapping relations between strain and deformation of thin-plate structure was built to realize the mathematical transformation from the distribution strain to the continuous curvature information of the thin-plate structure.The angle-recursive algorithm was analyzed and improved,and then it was extended to a two-dimensional curvature recursion algorithm.Therefore,the deformation state of the thin-plate structure can be constructed by using the continuous curvature information.Through simulation comparison analysis,the effectiveness of the developed two-dimensional curvature recursion algorithm was verified.(3)An experimental platform for the deformation detection of the thin-plate structure was established.By arranging the improved FBG strain sensors,the two-dimensional strains at different positions of the thin-plate structure were detected.Then,the deformation of thin-plate structure was reconstruction by the two-dimensional curvature recursive algorithm.The effect of the reconstruction algorithm was verified by the laser displacement sensor and finite element simulation results.The results showed that the two-dimensional curvature recursion algorithm could accurately reconstruct the deformation of thin-walled structural members with the maximum error less than 6%.The FBG-based strain detection and deformation reconstruction technology for thin-plate structure has a good engineering application value.