Follower-Force Experiments with Geometric Nonlinear Coupling for Analytical Validation

In the following experimental study, static deflection data were collected from a joinedwing test article using a laser tracker while the test article was subjected to various followerforce magnitudes. The primary goal of this study was to collect accurate experimental data which could be later used to validate analytical methods, such as the geometrically exact beam theory, which are used to predict the nonlinear static response of joined-wings. Previous experimental research efforts did not use follower-forces, and therefore the loads were not representative of what the joined-wing would experience under more realistic loading conditions. The test articles used in these experiments are a qualification model and a joined-wing model. The qualification test article is simply a 72 in long, 8 in wide, and 0.5 in thick aluminum beam used mainly for validating the experimental procedures in preparation for the actual experiment on the joined-wing model. The joined-wing model is made up of two aluminum beams, similar in dimension to the qualification model, joined at the tip to represent the joined-wing configuration. The experimental data is compared to the results obtained from nonlinear finite element analyses to determine how close the analytical predictions are to the experimental data. The results of this study show that follower-force loads result in as much as 34% greater deflections in comparison to stationary direction force loads.