Forced Response Analysis Research Articles

Generalized coordinates affected by external term in dynamic response analysis (2nd report, Application to component mode synthesis)

In dynamic response analysis by component mode synthesis, we present the calculation method which always gives accurate value about not only nodal point displacement but also element stress. We consider that Craig-Bampton's method is excellent in free vibration analysis. But, when their method is applied to forced response analysis, there are instances where we can not bet correct stress value. We present new generalized coordinates that are shown in Fig.7(b). In this method gNh is zero, and generalized coordinates are orthonormalized about stiffness matrix. These generalized coordinates give fully satisfactory result (in Table 3, compare D with E, where A is exact).

Some results on the effect of interface friction damping on turbomachinery blade dynamics

The presentation will review problems of damping in turbomachinery blades and bladed disks. The blade-disk and blade-to-blade interface effects represent an important source of damping controlling vibration and stress levels. These effects are substantially nonlinear and depend on different factors (physical, micro, and macro-geometrical, kinematical). Their magnitude, however, exceeds the magnitude of damping brought to the system by internal (material) and external (fluid flow) dissipation of energy. A nonlinear discrete modelization based on modal analysis of forced response to periodic excitation of a single blade and bladed disk and the model identification based on experimental results will be discussed. The mathematical model of the system is being analyzed numerically. Some results of the calculations will be presented: the effects of phase differences between excitation forces at each blade, mistuning of blades, magnitude of excitation forces, magnitude of interblade and blade-disk friction forces, viscoelastic coupling between blades. The investigation throws light on blade-to-blade coupling effects and blade-root interaction. The results may be of interest to turbomachinery blade designers, who are concerned with development of frictional vibration control configurations.