Thermal deformation monitoring of large-scale composite honeycomb spaceborne antennas with limited strain measurements

Shape reconstruction of spaceborne antennas is essential for calibrating phase signals and ensuring structural safety, particularly in large-scale composite honeycomb structures subjected to thermal load. The inverse finite element method (iFEM) has emerged as a promising technique for shape reconstruction using surface-measured strains. However, due to the dense coverage of transmit/receive modules on one side of the structure and weight constraints, only a limited number of sensors can be attached to the surface without payloads. To overcome this limitation, this paper proposes a strain surrogate model-based inverse finite element method (SSM-iFEM) for real-time shape reconstruction using limited strain measurements from a single surface of the structure. The strain surrogate model employs a parallel multilayer perceptron (PMLP) neural network to establish the relationship between sparse strain measurements and strains on both surfaces. The PMLP consists of six parallel branches corresponding to the strain components in three directions on both surfaces. Furthermore, the displacement-curvature-strain relation is utilized for strain sample construction. In the iFEM formulation, an integral error function is applied to enhance the robustness of the algorithm. The proposed SSM-iFEM and strain sample construction method are validated using a numerical model of a large-scale composite structure under thermal load. Finally, the proposed method is applied to monitor the shape of the large-scale composite honeycomb structure during heating and cooling processes.