Time Domain Modeling of Geometrically Nonlinear Viscoelastic Beams for Rotor Blades

A geometrically nonlinear time domain viscoelastic beam model was formulated for modeling rotor blades within the framework of multi-body dynamics-based rotorcraft comprehensive analysis. The formulation was based on a slender beam in a moving frame and undergoing small strain and moderate local rotation. Anelastic Displacement Fields (ADFs) were used to model the viscoelastic materials where internal variables are introduced that interact with the mechanical displacement field of continuum mechanics. Examples of a cantilever beam and simple rotor blade with a viscoelastic flexbeam are provided to show that the beam model can accurately capture damping behavior in viscoelastic beams.