Structural modification (MODIFSTRUCT) ====================================== This structural modification technique is based on the substructuring method. The first substructure corresponds to the initial structure and the second substructure corresponds to the modification made. The initial structure is modelled on the basis of the eigenmodes identified experimentally. The second substructure is modelled numerically using finite elements. Except in very specific cases, the measurement points are not located at the level of the interface between the initial structure and the modification. It is therefore necessary to go through an intermediate step which consists in expanding the measurement on the interface degrees of freedom. This expansion is taking place via the digital support model. The following paragraphs describe the keywords required in CALC_ESSAI for this feature. More details on the method and on the principles of implementation in Code_Aster are given in the U2.07.03 documentation. Keyword MESURE ~~~~~~~~~~~~~~~ .. code-block:: text ♦ MESURE = measure [mode_meca] Measure is the name of the concept that contains the identified eigenmodes. Keyword MODELE_SUP ~~~~~~~~~~~~~~~~~~~ .. code-block:: text ♦ MODELE_SUP = model [model] Name of the support model on which the expansion base is built. Keyword MODELE_MODIF ~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text ♦ MODELE_MODIF = model [model] The name of the model for the change to the initial structure. Keyword MATR_RIGI ~~~~~~~~~~~~~~~~~~ .. code-block:: text ♦ MATR_RIGI = matrix, [matr_asse] Stiffness matrix defined on the support model, necessary for the calculation of static modes. Keyword RESOLUTION ~~~~~~~~~~~~~~~~~~~ .. code-block:: text ♦ RESOLUTION = /'ES', [DEFAUT] /' LMME ' This keyword allows you to choose the method used to calculate the expansion base. ES corresponds to static expansion and LMME corresponds to "Local Model Modeshapes Expansion". Keyword NUME_MODE_MESU ~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text ♦ NUME_MODE_MESU = L_I, [L_i] This keyword makes it possible to select the numbers of the modes to be used from among the identified specific modes. By default, all the specific modes of the measurement concept are taken into account. Keyword NUME_MODE_CALCUL ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text ♦ NUME_MODE_CALCUL = L_I, [L_i] This keyword allows you to select the numbers of the modes to be used among the vectors of the expansion base. By default, we take into account all the vectors of the expansion base. Keyword GROUP_NO_CAPTEURS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text ◊ GROUP_NO_CAPTEURS = _F (♦ GROUP_NO = gr_no, [mode_meca] ♦ NOM_CMP = cmp-name, [matr_asse] This keyword factor allows you to select the list of node groups that will be used to calculate the static modes associated with the measurement points. These node groups are defined on the support model. Keyword GROUP_NO_EXTERIEUR ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text ◊ GROUP_NO_EXTERIEUR = _F (♦ GROUP_NO = gr_no, [mode_meca] ♦ NOM_CMP = cmp-name, [matr_asse] This keyword factor makes it possible to define the groups of "external" nodes where the measured information will be condensed. These node groups should at least contain the interface between the support model and the change model. Product concepts --------------------- The user can specify the names of the concepts produced by the interface by entering the keyword factor RESU_MODIFSTRU. These concepts can then be used for later calculations. .. code-block:: text ◊ MODE_MECA = fashion, [mode_meca] mode will be the name of the concept that contains the modes specific to the modified structure. .. code-block:: text ◊ MODELE = model, [model] model will be the name associated with the model of the modified structure. .. code-block:: text ◊ MAILLAGE = mesh, [mesh] mesh will be the name of the mesh associated with the modified structure. .. code-block:: text ◊ NUME_DDL = number, [nume_ddl] nume will be the name of the nume_ddl concept associated with the modified structure. .. code-block:: text ◊ MASS_MECA = mass, [matr_asse] Mass will be the name of the concept that contains the assembled mass matrix of the modified structure. .. code-block:: text ◊ RIGI_MECA = raid, [matr_asse] raid will be the name of the concept that contains the assembled stiffness matrix of the modified structure. .. code-block:: text ◊ AMOR_MECA = love, [matr_asse] amor will be the name of the concept that contains the damping matrix assembled from the modified structure. .. code-block:: text ◊ MACR_ELEM = macrel, [macr_elem_stat] macrel will be the name of the concept that contains the macroelement where the measurement is condensed. .. code-block:: text ◊ PROJ_MESU = proj, [mode_gene] proj will be the name of the concept that contains the generalized coordinates of the modes identified relating to the expansion base. .. code-block:: text ◊ BASE_LMME = balsam, [mode_meca] balmme will be the name of the expansion base from the LMME method. .. code-block:: text ◊ BASE_ES = base, [mode_meca] baes will be the name of the expansion base resulting from static expansion (ES method). .. code-block:: text ◊ MODE_STAT = modest, [mode_stat_force] modest will be the name of the concept that contains the static modes associated with the measurement points.