CONCEPTUAL MODELING AND ANALYSIS OF A NONLINEAR DYNAMIC VIBRATION ABSORBER FOR HELICOPTER APPLICATIONS

This paper presents the conceptual modelling and numerical analysis of a nonlinear dynamic vibration absorber designed for integration into helicopter fuselage structures. While conventional dynamic vibration absorbers are typically tuned to a narrow frequency range and target a single excitation frequency, the proposed system introduces a nonlinear stiffness element, modeled as a polynomial function to enhance performance across multiple frequencies. The analysis focuses on vibration mitigation in the vertical (z-axis) direction, which is particularly critical for pilot comfort and structural durability. A performance comparison is conducted between the linear and nonlinear dynamic vibration absorbers under multiple harmonic excitation forces representative of rotor-induced vibrations. The nonlinear spring coefficients and absorber mass are optimized using a genetic algorithm to minimize the vibration amplitude of the main body. Simulation results show that the nonlinear vibration absorber can improve vibration suppression over a broader frequency range, making it a promising solution for enhancing vibration control in rotorcraft fuselage applications.