Dynamic bifurcations analysis of a micro rotating shaft considering non-classical theory and internal damping

Meccanica ◽  
2018 ◽  
Vol 53 (15) ◽  
pp. 3795-3814 ◽  
Author(s):  
S. Ali Ghasabi ◽  
Majid Shahgholi ◽  
Mohammadreza Arbabtafti
Keyword(s):  
Classical Theory ◽  
Internal Damping ◽  
Rotating Shaft ◽  
Dynamic Bifurcations

Nonlinear Effects of Surface Texturing on the Performance of Journal Bearings in Flexible Rotordynamic Systems

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Jocelyn Rebufa ◽  
Fabrice Thouverez ◽  
Erick Le Guyadec ◽  
Denis Mazuyer
Keyword(s):  
Harmonic Balance ◽  
Vibration Amplitude ◽  
Surface Texturing ◽  
Harmonic Balance Method ◽  
Nonlinear Effects ◽  
Coupled System ◽  
Journal Bearings ◽  
Internal Damping ◽  
Rotating Shaft ◽  
Mean Pressure

A dynamic model of a rotating shaft on two textured hydrodynamic journal bearings is presented. The hydrodynamic mean pressure is computed using multiscale periodic homogenization and is projected on a flexible shaft with internal damping. Harmonic balance method (HBM) is used to study the limit cycles of unbalance response of the coupled system discretized by finite element method (FEM). Stability is analyzed with Floquet multipliers computation. An example of an isotropic texturing pattern representing laser dimples on a lightweight rotor is analyzed. Vibration amplitude and stability zone are compared with plain bearing lubrication. It is shown in an example that full surface texturing leads to relatively higher vibration amplitude compared to plain bearings.

A Finite Rotating Shaft Element Using Timoshenko Beam Theory

1980 ◽  
Vol 102 (4) ◽  
pp. 793-803 ◽  
Author(s):  
H. D. Nelson
Keyword(s):  
Timoshenko Beam ◽  
Beam Theory ◽  
Timoshenko Beam Theory ◽  
Internal Damping ◽  
Theory Analysis ◽  
Rotating Shaft ◽  
Element Analysis ◽  
Rotor Systems ◽  
The Finite Element Analysis ◽  
Rotating Shafts

The use of finite elements for simulation of rotor systems has received considerable attention within the last few years. The published works have included the study of the effects of rotatory inertia, gyroscopic moments, axial load, and internal damping; but have not included shear deformation or axial torque effects. This paper generalizes the previous works by utilizing Timoshenko beam theory for establishing the shape functions and, thereby including transverse shear effects. Internal damping is not included but the extension is straight forward. Comparison is made of the finite element analysis with classical dosed form Timoshenko beam theory analysis for nonrotating and rotating shafts.

Analysis of Internal Damping in Rotating Shaft

2020 ◽  
pp. 695-707
Author(s):  
K. Raju ◽  
M. Ravindra Gandhi ◽  
Rajasekhar Vangala ◽  
N. Suresh
Keyword(s):  
Internal Damping ◽  
Rotating Shaft

Forced Oscillations of Rotating Shaft With Nonlinear Spring Characteristics and Internal Damping: Subharmonic Oscillation of Order 1/3 and Entrainment

1999 ◽  
Author(s):  
Yukio Ishida ◽  
Shin Murakami
Keyword(s):  
Critical Region ◽  
Critical Speed ◽  
Forced Oscillations ◽  
Ball Bearings ◽  
Internal Damping ◽  
Rotating Shaft ◽  
Nonlinear Spring ◽  
Subharmonic Oscillation

Abstract An elastic rotating shaft supported by ball bearings may have nonlinear spring characteristics due to clearance and internal damping due to friction between the shaft and the bearings. In such a system, self-excited oscillations appear in the post critical region and nonlinear forced oscillations appear at various resonance points. In this paper, a phenomenon in the neighborhood of the critical speed of the subharmonic oscillation of order 1/3 of a forward whirling mode is discussed. It is clarified that, similar to the case of the subharmonic oscillation of order 1/2 of a forward whirling mode, an entrainment phenomenon appears due to the interplay between self-excited oscillations and forced oscillations.

Critical Speeds of Rotating Shaft Subjected to Axial Loading and Tangential Torsion

1967 ◽  
Vol 89 (2) ◽  
pp. 259-264 ◽  
Author(s):  
N. Willems ◽  
S. M. Holzer
Keyword(s):  
Differential Equation ◽  
Boundary Conditions ◽  
Classical Theory ◽  
Axial Load ◽  
Galerkin Approximation ◽  
Axial Loading ◽  
Complex Form ◽  
Rotating Shaft ◽  
Special Cases ◽  
Predicted Values

In this study the classical theory of the bending and twisting of thin rods is utilized and applied to the case of a rotating shaft subjected to axial loading and tangential torsion. The differential equation of small bending oscillations in its complex form is solved by using a three-term Galerkin approximation satisfying the boundary conditions term by term. Convergence of the solution is indicated by comparing the two-term and three-term approximations. The special cases of a stationary shaft subjected to axial load or twist are discussed briefly. Experimental results closely agree with the theoretically predicted values.

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