Effects of centrifugal stiffening and spin softening on nonlinear modal characteristics of cyclic blades with impact–friction coupling

Abstract This paper aims to interpret the coupling modal properties of cyclic blades under impact–friction interactions and their evolution mechanism versus operating points. Therefore, a analytical model is developed based on Lagrange method assumed mode (AMM), after considering centrifugal stiffening, spin softening, stagger angle, twist angle. Then mixed analysis (MMAM) for this extended by combining periodic motion concept (EPMC) with AMM. Wherein classic alternating frequency/time (AFT) continuation are employed overcome numerical divergence problem. damped nonlinear normal modes (dNNMs), including eigenfrequencies, damping ratios, shapes, system shroud joints finally computed discussed different excitation levels contact conditions through synthesis algorithm. After that, influence laws stiffening softening dNNMs explored reveal its operation speeds. Finally, Campbell diagrams successfully obtained discuss effects critical speeds (CSs) shrouded system.