Estimation and elimination of eigenvalue splitting and vibration instability of ring-shaped periodic structure subjected to three-axis angular velocity components
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Abstract
Stable operation is one of the most crucial requirements for resonators in vibratory gyroscopes and ultrasonic motors, but eigenvalue splitting can deteriorate operation stability. This work aims at the estimation and elimination of eigenvalue splitting and vibration instability of resonators arranged in a fashion of ring-shaped periodic structures (RPS). An analytical model is developed by Hamilton’s principle, where in-plane bending displacements, grouped supports and angular velocity components applied about three orthogonal directions are incorporated. Eigensolutions for the proposed rotational and mirror symmetric topologies are formulated by perturbation-superposition method, based on which eigenvalue splitting, vibration instability and their evolution with grouped supports and angular velocity are examined. The results verify the behaviors of splitting and instability share similar rules with those RPS having equally-spaced supports, but they change remarkably with grouping patterns. The dependences of grouping patterns and parameters on vibrations are demonstrated based on sample RPS. The splitting and instability are estimated by eigensolutions, and they can be suppressed or even eliminated by the proposed two types of topologies. Comparisons between the two topologies are made in terms of the requirements from engineering practice. Main results are also compared with those in the open literature.
Keywords
Ring-shaped periodic structures Rotational symmetry Mirror symmetry Eigenvalue splitting Vibration instabilityAbbreviations
- RPS
Ring-shaped periodic structure
- BTW
Backward traveling wave
- FTW
Forward traveling wave
List of symbols
- kv, ku
Stiffnesses of uniform radial and tangential supports
- o0-x0y0z0
Inertial coordinates
- N
Number of discrete supports
- β
Discrete supports’ inclination angle relative to the radial direction
- ks
Stiffness of discrete supports
- i, j, k
Unit vectors of inertial coordinates
- o-xyz
Body-fixed coordinates
- Ω0
Revolution speed of body-fixed coordinates around inertial coordinates
- \( \varOmega_{x 0} \), \( \varOmega_{y 0} \), \( \varOmega_{z 0} \)
Speed components around the three axes of inertial coordinates
- q0
Arbitrary position on the neutral surface
- q1
Instantaneous position of q0 after vibration
- \( \varvec{r}_{{0}} \)
Displacement vector of geometric center relative to the origin of inertial coordinates
- \( \varvec{r}_{{\text{q}_{0} }} \)
An arbitrary point relative to the geometric center of undeformed circular ring
- \( \varvec{U}_{0} \)
The point relative to \( {\text{q}}_{0} \) regarding the deformed circular ring
- h
Radial thickness
- b
Axial height
- ρ
Density
- E
Young’s modulus
- R
Neutral circle radius
- o-rθ
Polar coordinates
- v, u
Radial and tangential displacements of a point on neutral plane in polar coordinates
- \( \theta \)
Position angle
- t
Time
- N1
Number of discrete support groups of rotational symmetric RPS
- N2
Number of discrete supports in each group of rotational symmetric RPS
- N3
Number of discrete support groups of mirror symmetric RPS
- N4
Number of discrete supports in each group of mirror symmetric RPS
- \( G_{\text{R}}^{i} \)
The ith (i = 1, 2,… N1) group in rotational symmetric topology in Fig. 2a
- \( {\text{L}}_{\text{R}}^{i,j} \)
The jth (j = 1, 2,… N2) support in the ith (i = 1, 2,… N1) group in rotational symmetric topology in Fig. 2a
- \( G_{\text{M}}^{i} \)
The ith (i = 1, 2) group in mirror symmetric topology in Fig. 2b
- \( {\text{L}}_{\text{R}}^{i,j} \)
The jth (j = 1, 2,… N4) support in the ith (i = 1, 2) group in mirror symmetric topology in Fig. 2b
- \( \theta_{i,j} \)
Position angle of the jth (j = 1, 2,… N2 in Fig. 2a or N4 in Fig. 2b) support of the ith (i = 1, 2,… N1 in Fig. 2a or N3 in Fig. 2b) group
- \( \alpha \)
Position angle between two adjacent supports in the same group
- T
Kinetic energy
- εθ
Tangential strain
- εθ0
Tangential strain in neutral plane
- εθ1
Membrane strain
- \( \hat{U}_{0} \)
Potential energy from bending deformation of circular ring
- A
Cross-section area
- I
Sectional moment of inertia
- \( \hat{U}_{1} \)
Potential energy of discrete supports
- \( \varepsilon \)
Non-dimensional small parameter
- \( \delta \)
Dirac delta function
- \( N_{\text{I}} \)
Group count, which satisfies \( N_{\text{I}} = N_{1} \) for rotational symmetric RPS or \( N_{\text{I}} = N_{3} \) for mirror symmetric one
- \( N_{\text{II}} \)
Support count in each group, which satisfies \( N_{\text{II}} = N_{2} \) for rotational symmetric RPS or \( N_{\text{II}} = N_{4} \) for mirror symmetric one
- \( \hat{U}_{2} \)
Potential energy of uniform external supports
- \( \bar{t} \)
Dimensionless time
- \( \bar{k}_{\text{s}} \)
Dimensionless support stiffness
- \( \bar{u} \)
Dimensionless tangential displacement
- \( \bar{v} \)
Dimensionless radial displacement
- \( \bar{k}_{u} \)
Dimensionless tangential support stiffness
- \( \bar{k}_{v} \)
Dimensionless radial support stiffness
- \( \varvec{v}_{o} \)
Revolution speed of the origin of body-fixed coordinates
- \( v_{0x} \), \( v_{0y} \), \( v_{0z} \)
Components of revolution speed in three orthogonal directions in body-fixed coordinates
- \( \bar{v}_{0x} \), \( \bar{v}_{0y} \), \( \bar{v}_{0z} \)
Dimensionless components of revolution speed in the three orthogonal directions in body-fixed coordinates
- \( r_{n0} \)
Eigenvalue of uniform circular ring
- rn
Eigenvalue of RPS
- rn1
The first-order perturbation of the eigenvalue of RPS
- \( A_{n} \)
Amplitude
- ~
Complex conjugate operation
- i
Imaginary unit, \( {\text{i}} = \sqrt { - 1} \)
- n
Wavenumber
- \( x_{1} \), \( x_{2} \)
Plural variables
- k, k1–k5
Positive integers
- \( x_{{{\text{q}}_{0} }} \), \( y_{{{\text{q}}_{0} }} \)
Coordinates of point \( {\text{q}}_{0} \)
- \( U_{0x} \), \( U_{0y} \)
Vibration displacements about x and y axes
Superscripts and subscripts
- x0, y0, z0
The three axes of the inertial coordinates
- v, u
Radial and tangential displacements
- c
Cosine
- s
Sine
- \( {\text{R}} \)
Rotational symmetry
- M
Mirror symmetry
- P
Pure-imaginary
- I
Impure-imaginary
- bs
Sine-mode of backward traveling wave
- bc
Cosine-mode of backward traveling wave
- fs
Sine-mode of forward traveling wave
- fc
Cosine-mode of forward traveling wave
Notes
Acknowledgements
Authors are grateful to the National Natural Science Foundation of China (Grant Nos. 51675368, 51721003 and 51705519) for supporting this research. Also, authors thank the reviewers and editor for their valuable comments and suggestions on this paper.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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