$$$$ VIBR NOTICE CHAT 11/09/12 21:18:31 7124 DATE 11/09/12 Operateur VIBRATION Voir aussi : VIBC, DIAG ------------------- |'PROCHE' ... | SOL1 = VIBRATION |'INTERVALLE' ... | RIG1 MASS1 ... |'SIMULTANE' ... | ... ('IMPR') ('TBAS') (LOG1) ; Description : _____________ The VIBRATION operator searches for the eigenvalues w and eigenmodes X of a physical system represented by its stiffness K and its mass M. Then it solves : [K - (2*pi*w)**2 M] X = 0 Contents : __________ RIG1 : physical system stiffness matrix (RIGIDITE type, RIGIDITE subtype) MASS1 : physical system mass matrix (RIGIDITE type, MASSE subtype) 'IMPR' : key word indicating that intermediate printings are requested 'TBAS' : key word indicating that the output of a TABLE of BASE_MODALE subtype is requested LOG1 : indicates whether negative eigen values are taken into account (LOGIQUE type, FAUX by default) SOL1 : generated object containing the eigen values and eigen modes (SOLUTION TYPE or TABLE TYPE if there is the key word TBAS) The search for the eigen modes is carried out differently according to the key word : --------------------- | 1st possibility | --------------------- SOL1 = VIBRATION 'PROCHE' LREEL1 ( LENTI1 ) RIG1 MASS1 ; The option 'PROCHE' corresponds to the subspace inverse iteration method. This algorithm is robust but can become costly when a large number of modes are sought. For each real FREQ from LREEL1 (LISTREEL type) and each integer N from LENTI1 ( LISTENTI type ) the N eigenvectors which frequencies are the closest to FREQ are computed. This lists must have the same length. --------------------- | 2nd possibility | --------------------- |'BASSE'| SOL1 = VIBRATION 'INTERVALLE' FLOT1 FLOT2 (| | N1) |'HAUTE'| RIG1 MASS1 ( 'MULT' ) The option 'INTERVALLE' corresponds to the bissection method. This algorithm is usually very costly compared to the others. The eigen modes which frequencies are contained in the (FLOT1,FLOT2) interval are requested. FLOT1 and FLOT2 are of FLOTTANT type. The search may be restricted to the N1 (ENTIER type) lowest frequencies ('BASSE' option) or highest frequencies ('HAUTE' option) in the given interval. Multiple eigenvectors could be found with the 'MULT' option. --------------------- | 3rd possibility | --------------------- SOL1 = VIBRATION 'SIMULTANE' FLOT1 N1 RIG1 MASS1 ; The option 'SIMULTANE' corresponds to the Lanczos method with re- orthogonalization. This algorithm is quite efficient when a large number of modes are sought. A sequence of N1 (ENTIER type) eigen modes whose frequencies are close to a FLOT1 value (FLOTTANT type) is requested. NOTES : _______ 1. Frequencies will be in a unit consistent with the ones used to calculate the matrices given as input in VIBR. 2. SOL1 structure with the key word 'TBAS' : SOL1 TABLE type object SOL1.'SOUSTYPE' = 'BASE_MODALE' SOL1.'MODES' = TAB2 (TABLE type object) TAB2.'SOUSTYPE' = 'BASE_DE_MODES' TAB2.'MAILLAGE' = MAIL1 MAIL1 : modes geometrical support (MAILLAGE type) TAB2.IMOD = TAB3 (TABLE type object) IMOD : number (ENTIER) varying from 1 to the number of calculated modes TAB3.'SOUSTYPE' = 'MODE' TAB3.'POINT_REPERE' = PT1 PT1 : POINT used to identify the mode TAB3.'NUMERO_MODE' = NUMOD NUMOD :ENTIER NUM RO DU MODE TAB3.'FREQUENCE' = FLOT1 FLOT1 : FLOTTANT eigen frequency value TAB3.'MASSE_GENERALISEE' = FLOT2 FLOT2 : FLOTTANT generalized mass value TAB3.'DEFORMEE_MODALE' = CH1 CH1 : eigen vector (CHPOINT) TAB3.'DEPLACEMENTS_GENERALISES' = TAB4 (TABLE type object) TAB4.'SOUSTYPE' = 'DEPLACEMENTS_GENERALISES' TAB4.1 = FLOT3 TAB4.2 = FLOT4 TAB4.3 = FLOT5 FLOT3, (resp. FLOT4 and FLOT5) : FLOTTANT value of the generalized displacement in the direction X (resp. Y and Z)
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