A non-intrusive frequency normalisation approach for uncertain response analysis of nonlinear dynamic systems

•A non-intrusive frequency normalisation technique is proposed for nonlinear systems with uncertainty.•The method is applied to a nonlinear system with cubic nonlinearity and a multi-DOF rub-impact rotor.•Working mechanism of the new technique is illustrated and quantitative error analysis is also carried out.•Robust and accurate uncertainty quantification of frequency responses with complex nonlinear behaviours.