High-fidelity modeling of flight control actuators in the presence of degradations in the rod-end.

In this thesis, the development of a model on Simulink of a rod-end will be discussed, which is modeled as a spherical joint. This thesis is a continuation of a previous thesis in which the rod-end had been simulated as a revolute joint and thus in 2D, while in this thesis, the decision was made to attempt to create a 3D model of the rod-end. Rod-ends are mechanical components that play a very important role in numerous mechanical applications, with one of the most important examples being the connection between the actuation system and the flight control surface of an aircraft. Therefore, it is necessary to create a model that can simulate their behavior as they are key components for safety. The rod-end has been modeled as two spheres, one inside the other, where the movement of the outer sphere is due to the actuation system while the movement of the outer sphere will move the flight control surface to which it is connected. The actuation system is a crank-connecting rod system where the actuator is positioned on the connecting rod. Thus, the actuator positioned on the connecting rod is subjected to elongation over time; the outer sphere, being integral with the end of the actuator, will move and collide with the inner sphere. The two spheres will exchange a force due to the contact, initiating motion in the inner sphere, which, being connected to the flight control surface, will generate an angular movement of the surface itself. Initially, the actuator is not considered, and the elongation is directly imposed at the end to which the sphere is connected to the connecting rod, in order to have a position input with infinite stiffness. Subsequently, the rod-end model with its actuation system is integrated with the model of an actuator, which was not the subject of study in this thesis, in order to have a more realistic and complete actuation system. Finally, the results generated by the model were analyzed to assess whether its performance can be considered satisfactory.