4. Examples

4.1. Definition of the frequency dependence of the properties of viscoelastic materials

# frequencies for which material parameters are given

list_f= DEFI_LIST_REEL (VALE =( 1,10,50,50,100,100,500,1000,1500,),);

# values (of the real part) of the Young’s modulus at the frequencies of list_f

list_E= DEFI_LIST_REEL (VALE =( 23.2E6,58.E6,145.E6,203.E6,348.E6,435.E6,464.E6,),);

# values of the loss factor at the frequencies of list_f

list_eta= DEFI_LIST_REEL (VALE =( 1.1,0.85,0.5,0.7,0.7,0.6,0.4,0.35,0.34,),);

dark= DEFI_FONCTION (NOM_PARA =” FREQ “,

VALE_PARA =list_f,

VALE_FONC =List,

INTERPOL =( “LIN”, “LIN”,),

PROL_DROITE =” LINEAIRE “,

PROL_GAUCHE =” CONSTANT “,);

fonc_eta= DEFI_FONCTION (NOM_PARA =” FREQ “,

VALE_PARA =list_f,

VALE_FONC =list_eta,

INTERPOL =( “LIN”, “LIN”,),

PROL_DROITE =” LINEAIRE “,

PROL_GAUCHE =” CONSTANT “,);

4.2. Calculation of complex eigenmodes

modes= DYNA_VISCO (MODELE =model,

CARA_ELEM =cara_ele,

# materials with constant properties:

MATER_ELAS =_F (E=2.1e11,

NU=0.3,

RHO =7800. ,

AMOR_HYST =0.002,

GROUP_MA =” SUPPORT “),

# materials with frequency-dependent properties:

MATER_ELAS_FO =_F (E=DARK_E,

AMOR_HYST =fond_eta,

RHO =1200. ,

NAKED=0.45,

GROUP_MA =” VISCO “),

TYPE_RESU =” MODE “,

TYPE_MODE =” BETA “,

# search frequency band

FREQ =( 1.,1500. ),

EXCIT =_F (CHARGE =condim),

);

4.3. Harmonic response calculation

DEFINITION FROM CHARGEMENT

excit= AFFE_CHAR_MECA (MODELE =model,

FORCE_NODALE =_F (GROUP_NO =”A”,

FZ=1.,),);

# DEFINITION DES FREQUENCES OF CALCUL OF THE REPONSE

listfr= DEFI_LIST_REEL (DEBUT =1. ,

INTERVALLE =( _F (JUSQU_A =500. ,

PAS =1.,),),);

# REPONSE HARMONIQUE

visco= DYNA_VISCO (MODELE =model,

CARA_ELEM =cara_ele,

EXCIT =_F (CHARGE =( condim, excited),),

MATER_ELAS =( _F (E=2.1E11,

NU=0.3,

RHO =7800. ,

AMOR_HYST =0.002,

GROUP_MA =” DESSOUS “),

_F (E=7.0E10,

NU=0.3,

RHO =2700. ,

AMOR_HYST =0.001,

GROUP_MA =” DESSUS “),),

MATER_ELAS_FO =( _F (E=dark_e,

AMOR_HYST =fond_eta,

RHO =1200. ,

NAKED=0.45,

GROUP_MA =” VOLUME “,),),

TYPE_RESU =” HARM “,

TYPE_MODE =” REEL “,

LIST_FREQ =list en,

# fields to be saved

NOM_CHAM =( “DEPL”, “VITE”),

# saving the specific modes of the structure:

MODE_MECA =CO (“modes”),

);