.. _V2.02.403:

**v2.02.403** SDLL403 - Vibrations of a rotating pendulum
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**Summary**

The field of application of this test is the modal analysis of structures. The structure studied is a pendulum rotating around a fixed axis and immersed in a field of gravity. The pendulum is itself articulated around an axis perpendicular to the axis of rotation and located at a certain distance from this one.

We are interested in the first six natural frequencies.

The interest of this test lies in the following aspects:


* modal analysis taking into account initial constraints (geometric stiffness)


* modal analysis taking into account centrifugal stiffness


* significant relative difference between two successive frequencies of the spectrum

Currently, taking into account centrifugal stiffening is only possible with volume elements. The element used is element HEXA20 and the Sorensen method is used to calculate the natural frequencies.

The first natural frequency is compared to an analytical reference. The following frequencies are compared to numerical values obtained by software independent of *Code_Aster* and using 'beam' and 'plane strain' models.


.. toctree::
    :hidden:

    self

.. toctree::
    :maxdepth: 2
    :numbered:

    Probl_me_de_r_f_rence
    Solution_de_r_f_rence
    Mod_lisation_A
    Synth_se_des_r_sultats