Aeronautical structures are increasingly aging, and the occurrence of unexpected loads could reduce their operability. A health and usage monitoring system would enable the continuous monitoring of the state of health of a structure and track its aging by a load monitoring system, which aims at the real‐time reconstruction of the loads acting on a structure. However, sometimes the loads and the induced strain and stress fields are difficult to be reconstructed exactly, as for complex loading due to flight maneuvers. In this work, the full strain and load fields of a structure are reconstructed by an inverse‐direct approach, leveraging on the calibration matrix approach. The latter exploits a least‐squares minimization of an error functional, defined as the comparison between measured strains in discrete positions and a numerical formulation of the same, to reconstruct an equivalent, however representative, load set. By assuming a linear relationship between strain and load through a calibration matrix, this minimization can be performed analytically, leading to a computationally very efficient algorithm that can be operated online. Once the equivalent load set is computed, the full strain field can be estimated relying on a second calibration matrix linking the external loads to the strain field of the complete structure. The method has been numerically tested with an unmanned aerial vehicle (UAV) subjected to aerodynamic pressure loads simulating flight maneuvers. Finally, the results are experimentally validated during a ground test program on a real UAV, proving the robustness to different experimental uncertainties.

中文翻译：

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航空结构载荷和应变监测的反直接方法的数值和实验验证

航空结构日益老化，意外负载的出现可能会降低其可操作性。健康和使用情况监视系统将能够通过负载监视系统连续监视结构的健康状态并跟踪其老化，该监视系统旨在实时重建作用在结构上的载荷。然而，有时由于飞行操纵而导致复杂载荷的情况下，载荷，感应应变和应力场难以精确地重建。在这项工作中，利用标定矩阵方法，通过逆向直接方法重建了结构的整个应变场和载荷场。后者利用误差函数的最小二乘最小化，定义为离散位置上测得的应变之间的比较及其数值公式，以重建等效但具有代表性的载荷集。通过假设应变和载荷之间通过校准矩阵的线性关系，可以通过分析来实现这种最小化，从而可以实现可在线操作的计算效率很高的算法。一旦计算出等效载荷集，就可以依靠将外部载荷链接到整个结构的应变场的第二个校准矩阵来估算整个应变场。该方法已在无人飞行器（UAV）上经受了模拟飞行机动的气动压力载荷的数值测试。最后，在实际的无人机上进行地面测试的过程中，对结果进行了实验验证，