This study proposed a method capable of reconstructing complex deformations of thin-walled special-section beam structures subjected to highly coupled loading cases, in terms of the combination of tension/compression, biaxial bending, and warping torsion. The complex beam deformation was decoupled, depending on axial strain measurement strategy on beam surface, and leads to reconstructed full-field displacements (deformed shapes) as the linear superposition of deformations subject to individual loading types. Full-filed strain/stress distributions can then be derived based on the reconstructed displacements. Particular efforts were focused on reconstructing beam deformation subject to warping torsion, where both rotations angles and warping displacements across the beam cross-section and along the beam length were identified precisely. As a proof-of-concept validation, the effectiveness of the method was examined using finite element analysis, where the deformed shape of a thin-walled hat-section beam under the coupling between uniaxial bending and warping torsion was reconstructed., Experiments were conducted subsequently to reconstruct deformation of an aluminum hat-section beam using distributed optical fiber sensors for the measurement of axial strains on the beam surface. The reconstructed full-field deformed shapes of the beam were compared with the three-dimensional displacement signals captured using a non-contact digital image correlation system. The effectiveness of the proposed methodology for complex deformation reconstruction is possible to be extended to a variety of thin-walled beam-type structures which are typical in civil and aerospace engineering, showing potential contributions in fields such as on-line structural health monitoring and active structural control.

中文翻译：

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基于原位应变测量的薄壁异截面梁结构全场复杂变形重建

本研究提出了一种方法，能够重建薄壁异型截面梁结构在高耦合载荷情况下的复杂变形，包括拉伸/压缩、双轴弯曲和翘曲扭转的组合。根据梁表面的轴向应变测量策略，复杂的梁变形被解耦，并导致重建的全场位移（变形形状）作为受各个载荷类型影响的变形的线性叠加。然后可以基于重建的位移导出全场应变/应力分布。特别的努力集中在重建受翘曲扭转影响的梁变形上，其中穿过梁横截面和沿着梁长度的旋转角度和翘曲位移都被精确识别。作为概念验证的验证，使用有限元分析检查了该方法的有效性，其中重建了单轴弯曲和翘曲扭转耦合下的薄壁帽形截面梁的变形形状。进行了实验。随后使用分布式光纤传感器重建铝帽截面梁的变形，以测量梁表面的轴向应变。将重建的光束全场变形形状与使用非接触式数字图像相关系统捕获的三维位移信号进行比较。所提出的复杂变形重建方法的有效性可以扩展到土木和航空航天工程中典型的各种薄壁梁型结构，