A dutilisation example of Code_Aster: calculation dun bent pipe

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

1/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

Organization (S):

EDF-R & D/AMA

Instruction manual
U1.0- booklet: Introduction to Code_Aster
Document: U1.05.01

An example of use of Code_Aster:
calculation of a bent pipe

Summary:

This document describes a simple example of use of Code_Aster which is provided with the procedure of
downloading of Code_Aster since the site code-aster.org.

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

2/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

Facts of the case

1.1 Geometry

The study relates to a piping including/understanding two right pipes and an elbow [Figure 1.1-a].

The geometrical data of the problem are as follows:

the length L

the two right pipes is 3 m,

the Rc radius of the elbow is 0.6 m,

the angle

elbow is 90 degrees,

the thickness of the right pipes and the elbow is 0.02 m,

and the radius external Re of the right pipes and the elbow is of 0.2 Mr.

section B

section D

section C

section A

With

Appear 1.1-a

Note:

The geometry of the problem has a symmetry compared to the plan (A, X, Y).

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

3/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

1.2 Loading

The boundary conditions are as follows:

there is embedding on the level of section A,

The loading applied is a constant force FY = 100.000 NR directed according to the axis Y and applied to
the section B,

1.3 Characteristics

material

The properties of material are those of A42 steel:

the Young modulus E = 204.000. E+6 NR/m

the Poisson's ratio

= 0.3.

Modeling of the problem

One can modelize the problem by elements of hull DKT.

2.1 Mesh

GMSH

In the case of modeling in elements hulls, the mesh consists of the discretization of
surface average piping. Geometry being symmetrical compared to the plan (A, X, Y), one
will net that a half surfaces. The mesh will have to be sufficiently fine to obtain a solution
specify (elements DKT with 3 nodes having an interpolation of command 1 out of membrane).

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

4/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

We propose the file geo GMSH producing this mesh:

//////////////////////////////////////////////////////////////

//Mesh of the pipe bent for gmsh 1.60

//////////////////////////////////////////////////////////////

//Variable

Rext = 0.2;

Ep = 0.02;

Rm = Rext - (Ep/2.) ;

RC = 0.6;

LG = 3.0;

H = 0.04;

Not (1) = {RC, LG, 0., H};

Not (2) = {RC, LG, 0.1, H};

Not (3) = {(- 1 * Rm), 0, 0, H};

Not (4) = {0, 0, Rm, H};

Not (5) = {Rm, 0, 0, H};

Not (6) = {0, 0, 0, H};

Circle (1) = {3,6,4};

Circle (2) = {4,6,5};

//1st right pipe

Extrude Line {2, {0, LG, 0}}

{Layers {50,90,1}; };

Extrude Line {1, {0, LG, 0}}

{Layers {50,91,1}; };

//Elbow

Extrude Line {3, {0,0,1}, {RC, LG, 0.}, - (pi/2)}

{Layers {30,93,1}; };

Extrude Line {7, {0., 0., 1.}, {RC, LG, 0.}, - (pi/2)}

{Layers {30,94,1}; };

//2nd right pipe

Extrude Line {11, {LG, 0,0}}

{Layers {50,95,1}; Recombine; };

Extrude Line {15, {LG, 0,0}}

{Layers {50,96,1}; Recombine; };

Coherence;

Physical Line (27) = {2,1};

Physical Line (28) = {23,19};

Physical Line (29) = {24,16,8,5,13,21};

Physical Surfaces (30) = {90,91,93,94,95,96};

Physical Not (31) = {3};

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

5/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

2.2 Controls

Aster

The right pipes and the elbow will be modelized by elements of hull (DKT).

Piping is embedded in its base, on all the nodes located in the Y=0 plan. Piping
present a symmetry plane Z=0.

An effort distributed F * directed according to the axis Y and applied to the section B, (the effort distributed is such as
2

moy

= the total force which one wishes to apply).

One will calculate the stress field by element to nodes (SIGM_ELNO_DEPL), for

each loading case. To use

NIVE_COUCHE

to define the level of calculation in

the thickness

The main stages of calculation with Aster are:

Mesh.

Definition of the finite elements used (

AFFE_MODELE

One will use the groups of meshs resulting from the mesh.

Definition and assignment of material (

DEFI_MATERIAU

and

AFFE_MATERIAU

The mechanical characteristics are identical on all the structure.

Assignment of the characteristics of the elements hulls (

AFFE_CARA_ELEM

) with in particular

the thickness and the vector V defining the reference mark of examination (key word ANGL_REP). One

can take for example V=Oz.

Definition of the boundary conditions and the loadings (

AFFE_CHAR_MECA

Resolution of the elastic problem for each loading case (

MECA_STATIQUE

Calculation of the stress field by elements to the nodes for each loading case (option
'

SIGM_ELNO_DEPL

').

Impression of the results (

IMPR_RESU

One will print in form listing average displacement on the section B as well as the values
maximum of the tensor of stresses.

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

6/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

2.3

Controls with the magnifying glass

We now will detail the controls necessary to the realization of calculation considered.

Command file

Explanations

# TITRATES PIPING COMPRISING AN ELBOW

# MODELING BY ELEMENTS HULLS DKT

# PRODUCES BY GMSH

The comments are preceded by sign #,

BEGINNING ();

Obligatory control to start…

PRE_GMSH ();

The mesh is with format GMSH

MALL = LIRE_MAILLAGE ();

Reading of the mesh in the file of mesh,
and creation of the concept

MALL

containing it

mesh with the format Aster

# Definition of the finite elements used

A model is a concept containing the types
finite elements useful for calculation

MODMECA=AFFE_MODELE (MAILLAGE=MAIL,

Associate the meshs of the mesh of the groups
GM30 and GM28

AFFE=_F (GROUP_MA= (“GM30”, “GM28”,),

PHENOMENE=' MECANIQUE',

MODELISATION=' DKT',),);

with mechanical finite elements of hull type
DKT

# Orientation of the normals to the hulls

re-entering in the GM30

MAIL=MODI_MAILLAGE (reuse =MAIL,

To modify the mesh MALL

MAILLAGE=MAIL,

ORIE_NORM_COQUE=_F (

by directing the normals

GROUP_MA=' GM30',

group GM30

VECT_NORM= (1.0, 0.0, 0.0,), according to the normal (1,0,0)
GROUP_NO=' GM31',),

defined on node GM31

MODELE=MODMECA,);

On model MODMECA

# Definition of material

ACIER=DEFI_MATERIAU (ELAS=_F (E=204000000000.0, characteristics of each material

constituting the mesh are provided

NU=0.3,),);

Young modulus and Poisson's ratio

CHMAT=AFFE_MATERIAU (MAILLAGE=MAIL,

On the mesh MALL

AFFE=_F (TOUT=' OUI',

and on all the meshs

MATER=ACIER,),); the material STEEL is affected

# Characteristic of the hulls

CARA_COQ=AFFE_CARA_ELEM (

The elementary characteristics are changed

MODELE=MODMECA,

On model MODMECA

COQUE=_F (

hulls

GROUP_MA= (“GM30”, “GM28”,), defined in groups GM30 and GM28

EPAIS=0.02,

by a thickness of hull of 0.2

ANGL_REP= (0.0, 90.0,),),); with a local reference mark (useful in

postprocessing)

# Definition of the boundary conditions

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

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Instruction manual

U1.0- booklet: Introduction to Code_Aster

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BLOCAGE=AFFE_CHAR_MECA (MODELE=MODMECA,

DDL_IMPO= (

For model MODMECA

_F (GROUP_MA=' GM27',
DX=0.0,
DY=0.0,
DZ=0.0,
DRX=0.0,
DRY=0.0,
DRZ=0.0,),

Nodes of the group of meshs

GM27

are embedded

_F (GROUP_MA=' GM29',
DZ=0.0,
DRX=0.0,
DRY=0.0,),),);

and nodes of the group of meshs

GM29

are

such as DZ=0, DRX=0 and DRY=0

# Definition of the loading

FYTOT = 100000.0;

Definition of the constant total force

EPTUB = 0.02;

Definition constant thickness of the tube

REXT = 0.2;

Definition of constant the radius external of
tube

RMOY=REXT - EPTUB/2

Calculation of the average radius of the tube

FYREP=FYTOT/2./PI/RMOY

Calculation of the total force to apply

CHARG1=AFFE_CHAR_MECA (MODELE=MODMECA,

Assignment on model MODMECA

FORCE_ARETE=_F (GROUP_MA=' GM28',

Of a force on edge GM28

FY=FYREP,),);

of value FYREP

# Resolution

Total ordering of resolution of the problems

statics in thermo linear elasticity

RESU1=MECA_STATIQUE (

RESU1

is the name of the concept result

MODELE=MODMECA

Model MODMECA

CHAM_MATER=CHMAT,

The material CHMAT field

CARA_ELEM=CARA_COQ,

Elementary characteristics (hulls)

CARA_COQ

EXCIT= (_F (CHARGE=BLOCAGE,),

The conditions limit BLOCKING

_F (CHARGE=CHARG1,),),);

Loading CHARG1

# Calculation of the stresses

RESU1=CALC_ELEM (reuse =RESU1,

reuse=RESU1

mean that one “enriches” it

concept

OPTION=' SIGM_ELNO_DEPL',

on model MODMECA

RESULTAT=RESU1,);

with the material CHMAT field

and elementary characteristics CARA_COQ

one calculates

“SIGM_ELNO_DEPL”

meaning

“forced calculated with the nodes of each

element starting from displacements “

# Impression of the results for visualization

with GMSH

DEFI_FICHIER (ACTION=' ASSOCIER',
UNITE=37,)

Definition of the logical unit for file GMSH

IMPR_RESU (MODELE=MODMECA,

Results are printed

FORMAT=' GMSH', UNITE=37,

coming from model MODMECA

RESU=_F (RESULTAT=RESU1,

the results are

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

8/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

NOM_CHAM= (“DEPL”,
“SIGM_ELNO_DEPL”,),)
)

with format GMSH
and are displacements
printed in the logical unit associated the file
“POST”

and come from RESU1

with format GMSH

and are the stresses with the nodes

printed in the logical unit associated the file
“POST”

and come from RESU1

DEFI_FICHIER (ACTION=' LIBERER',
UNITE=37)

Closing of the logical unit

# To create a group

MAIL=DEFI_GROUP (

A new group

reuse =MAIL,

reuse=MAIL

mean that one “enriches” it

concept mesh

MAILLAGE=MAIL,

From the mesh MALL

CREA_GROUP_NO=_F (

one creates a group nodes

GROUP_MA=' GM28',),);

coming from meshs GM28

# To create a table

TABDEP1=POST_RELEVE_T (ACTION=_F (

One creates a table TABDEP1 in postprocessing

INTITULE=' DEPB1',

whose name is “DEPB1”

GROUP_NO=' GM28',

who is based on group GM28

RESULTAT=RESU1,

and on results RESU1

NOM_CHAM=' DEPL',

displacements are wanted

TOUT_CMP=' OUI',

for all the components

OPERATION=' MOYENNE',),);

and the average

# To print a table

IMPR_TABLE (TABLE=TABDEP1,

table TABDEP1 is printed

FILTRE=_F (NOM_PARA=' QUANTITE',

the quantity is wanted

CRIT_COMP=' EQ',

who is worth exactly

VALE_K=' MOMENT_0',),

moment of command 0

NOM_PARA=' DY',);

on displacement following y

END ();

…

Obligatory control to close an execution

Visualization using GMSH

With version 7.4 of Code_Aster, the direct impression of the results to format GMSH is possible.
One will print on file SIGM of logical number of unit 37 stresses (component SIYY
only) for postprocessing with GMSH. This component represents in fact the component
axial all along piping (because of the orientation chosen in AFFE_CARA_ELEM):

IMPR_RESU (MODELE=MODMECA,

FORMAT=' GMSH',

UNITE=37,

RESU= (_F (RESULTAT=RESU1,

NOM_CHAM=' SIGM_ELNO_DEPL',

NOM_CMP= (“SIXX”, “SIYY”,),

)

Code_Aster

Version

7.4

Titrate:

An example of use of Code_Aster: calculation of a bent pipe

Date:

18/05/05

Author (S):

Mr. ABBAS, J.M. PROIX

Key

U1.05.01-B

Page

9/10

Instruction manual

U1.0- booklet: Introduction to Code_Aster

HT-66/05/004/A

Comparison of the results obtained

The results obtained by this modeling can be compared with those obtained by others
modeling of the same problem:

For the loading of force constant FY applied to the section B, one compares displacement
at the point B for various modelings.

The following table gives, for various modelings, of the indicative values obtained for
average refinements of the mesh:

Loading forces constant FY

Modeling DX

DRZ

beam flexibility = 1

 2.657E02

6.702E02

2.097E02

beam flexibility RCCM

 2.983E02

1.156E01

3.530E02

pipe 2.935E02

1.083E01

3.326E02

Hull (average displacement)

 2.891E02

1.053E01

3.242E02

3D (average displacement)

 2.907E02

1.065E01

The following graph introduces the deformation and the isovaleurs of axial stresses visualized using
GMSH.

0.000e+00

1.056e-01

DEPL

- 1.719e+08

1.659e+08

SIGM_ELNO_DEPL_SIYY