Bending Vibrations of a Circular Ring

Let us consider a circular ring. A radius R of the central line is 1 m.

A square cross-section is considerably smaller than the radius R . The length of the side of the square is equal 0.050 m .
Displacement along the normal of the ring is restricted. In-plane rotations are also restricted.

Bending Vibrations of a Circular Ring, the finite element model with restraints

The finite element model with restraints

The material properties are: the Young's modulus E = 2.0E+011 , Poisson's ratio ν=0.29, the density ρ = 7900 kg / m3.
Analytical solution of this problem is given by:
, .
Thus, f2 = 31.015 Hz , f3 = 87.723 Hz , f4 = 168.201 Hz, f5 = 272.017 Hz.

After carrying out calculation with the help of AutoFEM, the following results are obtained*:

Table 1. Parameters of finite element mesh

Finite Element Type

Number of nodes

Number of finite elements

linear triangle

1735

2958

Table 2. Result "Frequency"*

Numerical solution
Frequency fi*, Hz

Analytical solution
Frequency fi, Hz

Error δ = 100%*| fi* - fi| / | fi |

31.565

31.015

1.77

89.129

87.723

1.60

170.361

168.201

1.28

274.355

272.017

0.86

Bending Vibrations of a Circular Ring, modes of vibration

 

 

*The results of numerical tests depend on the finite element mesh and may differ slightly from those given in the table.

 

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