Shape sensing as a crucial component of structural health monitoring plays a vital role in real-time actuation and control of smart structures,and monitoring of structural integrity.As a model-based method,the inverse...Shape sensing as a crucial component of structural health monitoring plays a vital role in real-time actuation and control of smart structures,and monitoring of structural integrity.As a model-based method,the inverse finite element method(iFEM)has been proved to be a valuable shape sensing tool that is suitable for complex structures.In this paper,we propose a novel approach for the shape sensing of thin shell structures with iFEM.Considering the structural form and stress characteristics of thin-walled structure,the error function consists of membrane and bending section strains only which is consistent with the Kirchhoff–Love shell theory.For numerical implementation,a new four-node quadrilateral inverse-shell element,iDKQ4,is developed by utilizing the kinematics of the classical shell theory.This new element includes hierarchical drilling rotation degrees-of-freedom(DOF)which enhance applicability to complex structures.Firstly,the reconstruction performance is examined numerically using a cantilever plate model.Following the validation cases,the applicability of the iDKQ4 element to more complex structures is demonstrated by the analysis of a thin wallpanel.Finally,the deformation of a typical aerospace thin-wall structure(the composite tank)is reconstructed with sparse strain data with the help of iDKQ4 element.展开更多
A fiber-optic shape sensing based on 7-core fiber Bragg gratings(FBGs)is proposed and experimentally demonstrated.The investigations are presented for two-dimensional(2D)and three-dimensional(3D)shape reconstruction b...A fiber-optic shape sensing based on 7-core fiber Bragg gratings(FBGs)is proposed and experimentally demonstrated.The investigations are presented for two-dimensional(2D)and three-dimensional(3D)shape reconstruction by distinguishing bending and twisting of 7-core optical fiber with FBGs.The curvature and bending orientation can be calculated by acquiring FBG wavelengths from any two side cores among the six outer cores.And the shape sensing in 3D space is computed by analytic geometry theory.The experiments corresponding of 2D and 3D shape sensing are demonstrated and conducted to verify the theoretical principles.The resolution of curvature is about 0.1 m^(-1) for 2D measuring.The error of angle in shape reconstruction is about 1.89°for 3D measuring.The proposed sensing technique based on 7-core FBGs is promising of high feasibility,stability,and repeatability,especially for the distinguishing ability on the bending orientation due to the six symmetrical cores on the cross-section.展开更多
This dissertation aims at providing steady sensing for the shape detection of colonoscopes. The research especially deals with the key techniques of fiber bragg grating (FBG) large curvature sensor and sensor net, int...This dissertation aims at providing steady sensing for the shape detection of colonoscopes. The research especially deals with the key techniques of fiber bragg grating (FBG) large curvature sensor and sensor net, integrates the techniques of mechatronics and computer graphics, and develops real time FBG shape sensing system and incremental shape sensing system for colonoscopies.展开更多
Thin plate and shell structures are extensively used in aerospace,naval,and energy sectors due to their lightweight and efficient load-bearing properties.Structural Health Monitoring(SHM)implementations are becoming i...Thin plate and shell structures are extensively used in aerospace,naval,and energy sectors due to their lightweight and efficient load-bearing properties.Structural Health Monitoring(SHM)implementations are becoming increasingly important in these industries to reduce maintenance costs,improve reliability,and ensure safe operations.This study presents an efficient triangular inverse shell element for thin shell structures,developed using discrete Kirchhoff assumptions within the inverse finite element method(iFEM)framework.The proposed inverse formulation is efficient and requires fewer strain sensors to achieve accurate and reliable displacement field reconstruction than existing inverse elements based on the First Order Shear Deformation Theory(FSDT).These features are critical to iFEM-based SHM strategies for improving real-time efficiency while reducing project costs.The inverse element is rigorously validated using benchmark problems under in-plane,out-of-plane,and general loading conditions.Also,its performance is compared to an existing competitive inverse shell element based on FSDT.The inverse formulation is further evaluated for robust shape-sensing capability,considering a real-world structural configuration under a practicable sparse sensor arrangement.Additional investigation includes defect characterization and structural health assessment using damage index criteria.This research contributes toward developing more reliable and cost-effective monitoring solutions by highlighting the potential application of the proposed inverse element for SHM frameworks designed for thin shell structures.展开更多
基金The author received funding for this study from National Key R&D Program of China(2018YFA0702800)National Natural Science Foundation of China(11602048)This study is also supported by National Defense Fundamental Scientific Research Project(XXXX2018204BXXX).
文摘Shape sensing as a crucial component of structural health monitoring plays a vital role in real-time actuation and control of smart structures,and monitoring of structural integrity.As a model-based method,the inverse finite element method(iFEM)has been proved to be a valuable shape sensing tool that is suitable for complex structures.In this paper,we propose a novel approach for the shape sensing of thin shell structures with iFEM.Considering the structural form and stress characteristics of thin-walled structure,the error function consists of membrane and bending section strains only which is consistent with the Kirchhoff–Love shell theory.For numerical implementation,a new four-node quadrilateral inverse-shell element,iDKQ4,is developed by utilizing the kinematics of the classical shell theory.This new element includes hierarchical drilling rotation degrees-of-freedom(DOF)which enhance applicability to complex structures.Firstly,the reconstruction performance is examined numerically using a cantilever plate model.Following the validation cases,the applicability of the iDKQ4 element to more complex structures is demonstrated by the analysis of a thin wallpanel.Finally,the deformation of a typical aerospace thin-wall structure(the composite tank)is reconstructed with sparse strain data with the help of iDKQ4 element.
基金supported in part by Major Technique Innovation Program of Hubei Province of China(Grant No.2018AAA016)the National Natural Science Foundation of China(NSFC)(Grant No.61575151).
文摘A fiber-optic shape sensing based on 7-core fiber Bragg gratings(FBGs)is proposed and experimentally demonstrated.The investigations are presented for two-dimensional(2D)and three-dimensional(3D)shape reconstruction by distinguishing bending and twisting of 7-core optical fiber with FBGs.The curvature and bending orientation can be calculated by acquiring FBG wavelengths from any two side cores among the six outer cores.And the shape sensing in 3D space is computed by analytic geometry theory.The experiments corresponding of 2D and 3D shape sensing are demonstrated and conducted to verify the theoretical principles.The resolution of curvature is about 0.1 m^(-1) for 2D measuring.The error of angle in shape reconstruction is about 1.89°for 3D measuring.The proposed sensing technique based on 7-core FBGs is promising of high feasibility,stability,and repeatability,especially for the distinguishing ability on the bending orientation due to the six symmetrical cores on the cross-section.
文摘This dissertation aims at providing steady sensing for the shape detection of colonoscopes. The research especially deals with the key techniques of fiber bragg grating (FBG) large curvature sensor and sensor net, integrates the techniques of mechatronics and computer graphics, and develops real time FBG shape sensing system and incremental shape sensing system for colonoscopies.
文摘Thin plate and shell structures are extensively used in aerospace,naval,and energy sectors due to their lightweight and efficient load-bearing properties.Structural Health Monitoring(SHM)implementations are becoming increasingly important in these industries to reduce maintenance costs,improve reliability,and ensure safe operations.This study presents an efficient triangular inverse shell element for thin shell structures,developed using discrete Kirchhoff assumptions within the inverse finite element method(iFEM)framework.The proposed inverse formulation is efficient and requires fewer strain sensors to achieve accurate and reliable displacement field reconstruction than existing inverse elements based on the First Order Shear Deformation Theory(FSDT).These features are critical to iFEM-based SHM strategies for improving real-time efficiency while reducing project costs.The inverse element is rigorously validated using benchmark problems under in-plane,out-of-plane,and general loading conditions.Also,its performance is compared to an existing competitive inverse shell element based on FSDT.The inverse formulation is further evaluated for robust shape-sensing capability,considering a real-world structural configuration under a practicable sparse sensor arrangement.Additional investigation includes defect characterization and structural health assessment using damage index criteria.This research contributes toward developing more reliable and cost-effective monitoring solutions by highlighting the potential application of the proposed inverse element for SHM frameworks designed for thin shell structures.
