Pre-Test of a Light-Weight CFRP Wing Segment of a High Altitude Platform for In-flight Load Measurements Based on Strains

Abstract

For the validation of loads and aeroelastic simulations of a high altitude platform (HAP) in-flight, load measurements are very helpful. One technique to obtain load measurements is to apply strain gages to the primary structure. A calibration procedure enables the reconstruction of the loads from the measured strains. To reduce the risks, gain confidence and establish a feasible measurement set-up, a pre-test based on a CFRP wing segment is performed. This paper presents the theoretical background and the set-up of the measurement equipment. The results of the calibration from three different test cases are presented, showing an excellent agreement between applied and reconstructed loading with a deviation of < +/- 1.0 N and < +/- 2.0 cm for the location. Finally, the strains measured in the experiment are compared with the simulation, showing that a prediction of the strains is possible within a range of < +/- 8%.