Comprehensive Modeling and Dynamic Stiffness Analysis of an Electromechanical Fin-Actuator System Considering Multiple Nonlinear Couplings

Electromechanical actuators play a crucial role in diverse engineering and physics fields, particularly in the aerospace and automotive industries. Their dynamic characteristics significantly affect the aeroelastic behavior of fins, especially regarding the flutter boundary. Nevertheless, ascertaining the dynamic characteristics of these actuators requires navigating the intricate interactions of multiple linear and nonlinear components. This study introduces a high-fidelity dynamic model designed to effectively address the complexities inherent in an electromechanical fin-actuator system. The model incorporates essential nonlinear elements, such as friction torque and dynamic backlash, along with fundamental components like the gear reducer, ball screw, transmission fork, and servomotor. To clarify these complex interactions, advanced models, namely, the LuGre model, the Bai model (an enhanced version of the Flores model), and the Kahraman model—are integrated into our framework. A comparative analysis is conducted between this complex nonlinear model and a simpler linear counterpart. This comparison is facilitated by rigorous numerical simulations that employ stepped frequency sweeping across various parameter configurations. The findings reveal that the dynamic stiffness characteristics of the fin shaft are markedly complicated under the combined effects of numerous nonlinear factors. Specifically, nonlinear friction originating from the friction ring diminishes response amplitude and seemingly augments the dynamic stiffness of the actuator due to reduced deflections under loads. Conversely, increased clearance among components can lead to a decrement in the dynamic stiffness amplitude of the actuator.