﻿ Harmonic Analysis of A Tower with Mechanical LossExamples | Product | Murata Software Co., Ltd.

# Example50Harmonic Analysis of A Tower with Mechanical Loss

General

• A tower which has certain mechanical loss is forced to oscillate.

• The relation between the oscillation amplitude and the mechanical loss is examined.

• Unless specified in the list below, the default conditions will be applied.

### Analysis Space

 Item Settings Analysis Space 3D Model unit m

### Analysis Conditions

The analysis type is harmonic analysis.

 Item Settings Solvers Mechanical Stress Analysis [Galileo] Analysis Type Harmonic analysis

The harmonics analysis tab is set up as follows.

 Item Settings Sweep Type Linear step by frequency Setting Minimum frequency : 0.8[Hz] Maximum frequency : 1.0[Hz] interval : 0.01[Hz]

### Model

The forced oscillations are applied on the bottom of the tower. The applied amplitude is set to 0.1[m] on the bottom as boundary condition.

### Body Attributes and Materials

 Body Number/Type Body Attribute Name Material Name 0/Solid Tower 002_Polycarbonate(PC) *

* Available in Material DB. However the mechanical loss tanδ is set to 0.1 without any bases.

### Boundary Conditions

 Boundary Condition Name/Topology Tab Boundary Condition Type Settings Move/Face Mechanical Displacement Select all X/Y/Z components. UX=0.1, UY=0, UZ=0 [m]

### Results

If the loss is considered, the displacement might not be the maximum at the phase 0° due to the phase shift. To prevent it, [Absolute] is selected to show the maximum displacement.

The relation between the displacement amplitude at the top of the tower and the oscillation frequency is shown in the following graph.

Three curves shown in this graph are obtained by different tanδ values (0.05, 0.1, 0.2).

When smaller tanδ value is set, the shape of the curve becomes steeper.

The displacement shown below is when 0.88[Hz] oscillation is applied. The tanδ value is set to 0.1.

While the amplitude applied on the bottom of the tower is 0.1[m], the amplitude of the generated oscillation is 2.2[m] at the top of the tower.

(Note) Resonant analysis is available by changing the analysis type to resonant analysis. In this case, however, the displacement setting (0.1[m]) on the bottom of the tower will be ignored. (In resonant analyses, oscillation amplitude can not be specified.)

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