Dynamic stability of rotating pre-twisted blades with a constrained damping layer

The stability problems of a rotating pre-twisted blade with a viscoelastic core constrained by a laminated face layer subjected to a periodic axial load are studied by using the finite element method. The complex modulus representation is used for the viscoelastic material. A set of equations of motion governing the bending and extensional displacements are derived by Hamilton’s principle. The regions of instability are determined by using Bolotin’s procedure that modified for the complex case. The effects of rotating speed, pre-twisted angle, setting angle and static axial load on the first static buckling load under different shear parameter and core loss factor are presented. The influences of core loss factor, core thickness ratio and stiffness parameter on the unstable regions are also studied. The shear parameter exists an optimal range in which the width of unstable region is narrowest.