Experimental and Numerical Investigation of the Nonlinear Bending-Torsion Coupling of a Clamped-Clamped Beam with Centre Masses

The vibration characteristics of beams have been extensively studied due to their wide application across multiple fields (i.e. spacecraft antennae, aircraft wings, turbine blades, skyscrapers). Of particular interest, specific geometries of beams have been shown to induce coupling between the fundamental bending and torsion modes. This coupled motion can be observed in a beam’s linear normal modes can be avoided with the correct selection of geometric properties. This work investigates the coupled bending-torsion behaviour of a clamped-clamped beam that is coupled perpendicularly, mid-span to mid-span, to a second beam with tip masses within the nonlinear response regime. The first torsion mode of the beam system is tuned by modifying the mass distribution such that closely spaced bending and torsion linear normal modes can be realized. The nonlinear behaviour is presented using nonlinear normal mode backbone curves and forced responses in the vicinity of the modes of interest.