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#1 2019-11-06 20:31:34

PATCH
Member
From: Brno, Czech Republic
Registered: 2017-01-03
Posts: 28

Harmonic analysis - acceleration base excitation

Hi,
I am new in frequency domain analysis in Code_Aster so I would like to create basic analysis. I am working regularly in Abaqus and running *Steady state dynamics to evaluate fixture performance. For this purpose I create MPC to all bolts holes that holds fixture and load control point with acceleration 1g load (9.81 m/s2) and check how fixture amplifies the signal in different locations.

My question is how can I simulate this in Code_Aster? Do you have any examples?

PATCH

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#2 2019-11-15 19:32:38

PATCH
Member
From: Brno, Czech Republic
Registered: 2017-01-03
Posts: 28

Re: Harmonic analysis - acceleration base excitation

Hi everybody,
Can anybody help with this topic? I am enclosing my current progress with this analysis. Currently the analysis runs but gives me zero response which is not correct .

PATCH

Attachments:

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#3 2021-05-06 09:57:29

cwf007
Member
From: Malaysia
Registered: 2020-06-05
Posts: 18

Re: Harmonic analysis - acceleration base excitation

Hi all,

Im curious on this also, can we input enforced acceleration as input for harmonic response analysis in CA???

Thank you.
cwf007.

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#4 2021-05-07 07:56:56

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Harmonic analysis - acceleration base excitation

Below .comm can give you idea.

DEBUT(LANG='EN')

mesh = LIRE_MAILLAGE(UNITE=20)

model = AFFE_MODELE(AFFE=_F(MODELISATION=('3D', ),
PHENOMENE='MECANIQUE',
TOUT='OUI'),
MAILLAGE=mesh)

mater = DEFI_MATERIAU(ELAS=_F(E=210000.0,
NU=0.3,
RHO=7.8e-09))

fieldmat = AFFE_MATERIAU(AFFE=_F(MATER=(mater, ),
TOUT='OUI'),
MODELE=model)

listR = DEFI_LIST_REEL(DEBUT=0.0,
INTERVALLE=_F(JUSQU_A=150.0,
PAS=0.1))

formula = FORMULE(NOM_PARA=('INST', ),
VALE='sin(2*pi*205.0*INST)')

func2d = CALC_FONC_INTERP(FONCTION=formula,
INTERPOL=('LIN', ),
LIST_PARA=listR,
PROL_DROITE='LINEAIRE',
PROL_GAUCHE='EXCLU')

PESANTEUR=_F(DIRECTION=(0.0, 0.0, -1.0),
GRAVITE=9850.0,
GROUP_MA=('vol', )))

LIAISON='ENCASTRE'),
MODELE=model)

MODELE=model)

ASSEMBLAGE(CHAM_MATER=fieldmat,
MATR_ASSE=(_F(MATRICE=CO('ma'),
OPTION='MASS_MECA'),
_F(MATRICE=CO('ka'),
OPTION='RIGI_MECA')),
MODELE=model,
NUME_DDL=CO('nddl'),
OPTION='CHAR_MECA',
VECTEUR=CO('fz')))

resharm0 = DYNA_VIBRA(BASE_CALCUL='PHYS',
CHAM_MATER=fieldmat,
EXCIT=_F(FONC_MULT=func2d,
VECT_ASSE=fz),
INCREMENT=_F(LIST_INST=listR),
MATR_MASS=ma,
MATR_RIGI=ka,
MODELE=model,
SCHEMA_TEMPS=_F(SCHEMA='NEWMARK'),
SOLVEUR=_F(METHODE='MUMPS',
NPREC=11,
PCENT_PIVOT=2000,
RENUM='AUTO'),
TYPE_CALCUL='TRAN')

restran = REST_SPEC_TEMP(METHODE='PROL_ZERO',
NOM_CHAM=('ACCE', ),
RESULTAT=resharm0,
SYMETRIE='OUI',
TOUT_CHAM='OUI')

INTITULE='dfft',
NOM_CHAM='ACCE',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=restran),
TITRE='LISTR=1000')

INTITULE='DISPLACEMENT',
NOM_CHAM='DEPL',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=resharm0))

IMPR_TABLE(FORMAT='XMGRACE',
IMPR_FONCTION='OUI',
LEGENDE_X='frequency',
LEGENDE_Y='amplitude',
NOM_PARA=('FREQ', 'DZ'),
PILOTE='EPS',
TABLE=table,
UNITE=29)

IMPR_TABLE(FORMAT='XMGRACE',
IMPR_FONCTION='OUI',
LEGENDE_X='TIME-SEC',
LEGENDE_Y='DISPL-MM',
MARQUEUR=0,
NOM_PARA=('INST', 'DZ'),
PILOTE='EPS',
STYLE=1,
TABLE=table1,
UNITE=10)

FIN()

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#5 2021-05-07 07:58:57

sameer21101970
Banned
Registered: 2019-09-06
Posts: 354

Re: Harmonic analysis - acceleration base excitation

POURSUITE(LANG='EN',
PAR_LOT='NON')

field = CALC_CHAR_SEISME(DIRECTION=(0.0, 0.0, 1.0),
MATR_MASS=MA,
MONO_APPUI='OUI')

resharm = DYNA_VIBRA(BASE_CALCUL='PHYS',
CHAM_MATER=fieldmat,
EXCIT=_F(FONC_MULT=func2d,
VECT_ASSE=field),
INCREMENT=_F(LIST_INST=listr),
MATR_MASS=MA,
MATR_RIGI=KA,
MODELE=model,
SCHEMA_TEMPS=_F(SCHEMA='NEWMARK'),
SOLVEUR=_F(METHODE='MUMPS',
RENUM='AUTO'),
TYPE_CALCUL='TRAN')

INTITULE='dz',
NOM_CHAM='DEPL',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=resharm))

restran = REST_SPEC_TEMP(METHODE='PROL_ZERO',
NOM_CHAM=('DEPL', 'ACCE', 'VITE'),
RESULTAT=resharm,
TOUT_CHAM='OUI')

INTITULE='dfft',
NOM_CHAM='ACCE',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=restran))

INTITULE='displ',
NOM_CHAM='DEPL',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=restran))

INTITULE='VELOCITY',
NOM_CHAM='VITE',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=restran))

INTITULE='ACCER',
NOM_CHAM='ACCE',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=resharm))

INTITULE='VELOCITY',
NOM_CHAM='VITE',
OPERATION=('EXTRACTION', ),
RESULTANTE=('DZ', ),
RESULTAT=resharm))

IMPR_RESU(FORMAT='MED',
RESU=_F(RESULTAT=resharm),
UNITE=80)

IMPR_TABLE(FORMAT='XMGRACE',
IMPR_FONCTION='OUI',
LEGENDE_X='TIME-SEC',
LEGENDE_Y='DISPLCEMENT',
MARQUEUR=0,
NOM_PARA=('INST', 'DZ'),
PILOTE='EPS',
STYLE=1,
TABLE=table,
TITRE='DISPL VS TIME',
UNITE=13)

IMPR_TABLE(FORMAT='XMGRACE',
LEGENDE_X='FREQUENCY',
LEGENDE_Y='AMPLITUDE',
MARQUEUR=0,
NOM_PARA=('FREQ', 'DZ'),
PILOTE='EPS',
STYLE=1,
TABLE=table1,
TITRE='ACCELERATION AS INPUT',
UNITE=29)

IMPR_TABLE(FORMAT='XMGRACE',
IMPR_FONCTION='OUI',
LEGENDE_X='FREQ',
LEGENDE_Y='AMPLITUDE',
MARQUEUR=0,
NOM_PARA=('FREQ', 'DX'),
PILOTE='EPS',
STYLE=1,
TABLE=table0,
TITRE='DISPLACEMENT AS INPUT',
UNITE=12)

IMPR_TABLE(FORMAT='XMGRACE',
IMPR_FONCTION='OUI',
LEGENDE_X='FREQ',
LEGENDE_Y='AMPLITUDE',
MARQUEUR=0,
NOM_PARA=('FREQ', 'DZ'),
PILOTE='EPS',
STYLE=1,
TABLE=table2,
TITRE='VELOCITY AS INPUT',
UNITE=10)

IMPR_TABLE(FORMAT='XMGRACE',
IMPR_FONCTION='OUI',
LEGENDE_X='TIME SEC',
LEGENDE_Y='ACCELERATION -MM/SEC2',
MARQUEUR=0,
NOM_PARA=('INST', 'DZ'),
PILOTE='EPS',
STYLE=1,
TABLE=table3,
TITRE='ACCELERATION VS TIME',
UNITE=11)

IMPR_TABLE(FORMAT='XMGRACE',
IMPR_FONCTION='OUI',
LEGENDE_X='TIME-SEC',
LEGENDE_Y='VELOCITY MM/SEC',
MARQUEUR=0,
NOM_PARA=('INST', 'DZ'),
PILOTE='EPS',
STYLE=1,
TABLE=table4,
TITRE='TIME VS VELOCITY',
UNITE=14)

FIN()

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#6 2021-05-11 07:57:20

cwf007
Member
From: Malaysia
Registered: 2020-06-05
Posts: 18

Re: Harmonic analysis - acceleration base excitation

Hi sameer,

It is so kind of you.

I found it more convenient to convert the acce to FORCE_NODALE for Aster.
It yield the same FRF.

Thank you.

Warmest Regards,
cwf007.

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#7 2021-05-11 14:14:14

statist
Member
From: Russia, St.-Petersburg
Registered: 2020-11-16
Posts: 17

Re: Harmonic analysis - acceleration base excitation

Hi, cwf007! I'm not good specialist in frequency response in code_aster, but on this youtube channel got helpful information for this type analysis in Code_Aster.

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#8 2021-05-12 02:17:41

cwf007
Member
From: Malaysia
Registered: 2020-06-05
Posts: 18

Re: Harmonic analysis - acceleration base excitation

Hi Statist,

It gives the idea on how to setup harmonic response (DYNA_VIBRA + REST_GENE_PHYS) from scratch.

Thank you!
cwf007.

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#9 2021-05-12 09:24:49

statist
Member
From: Russia, St.-Petersburg
Registered: 2020-11-16
Posts: 17

You are welcome!

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