D modeling
====

Geometry
----

Geometry can be created by defining the points :math:`A,C,D,B`, then the two lines :math:`\mathrm{AC}` and :math:`\mathrm{DB}`, and the arc of a circle :math:`\mathrm{CD}`. This can be done in several ways:

• By defining the coordinates of each point, including the midpoint of arc :math:`\mathit{CD}` (Menu New Entity → Basic →...);

• In a simpler way using the "Sketcher" tool (New Entity Menu → Basic→2D Sketch).

After building the entire line, you must define the groups under this "Wire": for this practical work, it will suffice to create the groups :math:`A`, :math:`B`, :math:`\mathrm{AC}`, :math:`\mathrm{CD}`, and :math:`\mathrm{DB}` (Menu New Entity → Group → Create Group) (Menu New Entity → Group → Create Group).


Meshing
----

Launch the Mesh module of the Salome-Meca platform.

The mesh is defined by the Mesh → Create Mesh menu. Select the geometry to be meshed, then the algorithm and the hypothesis of discretization by dimension: 1D Wire Discretization with the hypothesis of 15 segments per edge.


Creation and launch of the calculation case (via asterStudy)
----

Launch the AsterStudy module from the Salome-Meca platform.

Then in the left column, click on the Case View tab.

The command file for the calculation case is defined.

Note: Add orders using the Commands menu → Show All.

The study requires a first transitory thermal calculation followed by a mechanical calculation.

The main steps for creating and launching the calculation case are as follows:


*   Read the mesh in MED format: Command LIRE_MAILLAGE.


*   Define the finite elements used: Command AFFE_MODELE.


*   Define material: Command DEFI_MATERIAU.


*   Assign material: Command AFFE_MATERIAU.


*   Affect the characteristics of the beam elements: Command AFFE_CARA_ELEM.


*   Affect mechanical boundary conditions and loading: Command AFFE_CHAR_MECA/Enforce DOF (DDL_IMPO). Point :math:`A` is embedded.


*   Define the elastic problem matrices: Command ASSEMBLAGE/MASS_MECA and RIGI_MECA.


*   Calculate the first 5 natural modes: Command CALC_MODES.


*   Print the specific modes in format MED: Command IMPR_RESU. We will print the mesh and the modes.

To launch the calculation case, in the left column, click on the History View tab.

*Transient analysis:*


*   Construction of the point force


1.
    *
        *
            *   Assign the load "force to point :math:`B`": Command AFFE_CHAR_MECA/FORCE_NODALE.


            *   Calculate the elementary force vectors: Command CALC_VECT_ELEM.


            *   Build a field at the nodes by assembling the force vector: Command ASSE_VECTEUR.


            *   Define the time evolution function: Command FORMULE.


*   Transitional on a modal basis


1.  Projection of the assembled problem based on the specific modes: Command PROJ_BASE.


2.  Calculate the transient by modal recombination: Command DYNA_VIBRA.


3.  Extract the moves in :math:`Y` in :math:`B`: Command RECU_FONCTION.


4.  Print these functions in format TABLEAU: Command IMPR_FONCTION.