Modal analysis of a rotating pre-twisted beam axially loaded by an internally guided tendon

A guided tendon concept in the context of rotating helicopter blades is proposed to modify their dynamic characteristics, so that rotorcraft can operate under a wide range working conditions. In this paper, pre-twisted beam with bending-bending-torsion coupling axially loaded by used model system. An internally attached at several spanwise locations avoid resonant vibrations due insufficient separation between rotor harmonics and natural frequencies beam. set orthogonal polynomials satisfy geometric boundary conditions represent deflections tendon. The equations motion are derived means Lagrange's equation second kind combined appropriate energy expressions. vacuo modal analysis then carried out after properties without validated against reference. effect attachments rotation on free vibration beam-tendon system studied. It found improve structural stability significantly, as allow significantly larger axial force be applied. all studied modes increase centrifugal stiffening effect. tendon-guiding cause an tendon-dominated because reduced effective length but decrease frequency reduction rate beam-dominated applied force. part mode shapes not sensitive varying force, speed or number expect when enter veering regions other neighbouring modes.