A nonlinear deformation field reconstruction approach for hull girder structures

Le résumé fourni par la source

Among essential methodologies for ensuring the safety and integrity management of ship structures, Structural Health Monitoring (SHM) plays a fundamental role. The real-time reconstruction of structural deformation fields, derived from surface strain data collected by an array of on-board strain sensors, is generally known as Shape Sensing. Nevertheless, evaluating the nonlinear deformation fields and failure modes of complex ship structures under significant load remains a formidable challenge. This study proposes an innovative shape sensing methodology aimed at precisely and efficiently reconstructing the nonlinear deformation fields of thin-shell structures, employing limited discrete strain measurement data. First, based on First-order Shear Deformation Theory (FSDT), NURBS basis functions are employed in place of traditional interpolation shape functions used in finite element analysis to derive the relationship between measured strains and theoretical strains. A four-node inverse shell element, consistent with Kirchhoff shell theory, is utilized to obtain measurement data of membrane strain and bending strain. Subsequently, the model is optimized through a combination of the weighted least squares variational principle and reduction basis matrices constructed based on nonlinear strain increments. During this process, the model undergoes geometric updates via predicted deformation increments, integrating deformation continuity conditions and boundary conditions, thereby establishing a method suitable for real-time reconstruction of nonlinear deformation fields in complex ship structures. Finally, the validity and accuracy of this approach are verified through a four-point bending experiment on a box beam. Experimental results demonstrate that this nonlinear deformation field reconstruction method effectively captures the large deformation fields and failure modes of structures under ultimate loads, providing a novel research pathway for the rapid assessment of local hull failures, adjustment of model test decisions, and evaluation of structural failure behaviors.

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