Engineering Prediction Research of UAVs Structural Loads and Deformation Using Distributed Strain Measurement

For fixed-wing unmanned aerial vehicles (UAVs), especially during the demonstrator phase, accurate measurement of the actual wing loads and structural dynamic deformation during flight is a critical step. Traditional modeling methods based on rigid-body assumptions struggle to accurately represent real flight conditions. This study leverages distributed strain measurement technology to develop an engineering prediction method for UAV structural loads and deformation. It implements practical measurements during both ground tests and flight trials. By installing resistive strain gauges on the primary load-bearing structures (front and rear spars) and conducting ground flexibility calibration tests, a mapping relationship was established between strain signals and bending moments, shear forces, torque, and nodal displacements. Utilizing Ko's theoretical framework and combining it with aerodynamic calculation results from flight test conditions, the full-wing deformation field was reconstructed from measured strain data. During flight test measurements, precise prediction and monitoring of both load and deformation across the entire flight envelope were achieved. Flight validation demonstrated high prediction accuracy and good engineering robustness: 1) The load and deformation profiles during maneuvers correlated well with the maneuver load factors; 2) After altering the bending moment level via aileron deflection, the load measurements showed strong agreement with results from CFD/CSD fluid-structure interaction simulations.