Tube Creep

7/28/2019 Tube Creep

1/40

WS4-1

NAS133-a, Workshop 4, March 2009

Copyright 2009 MSC.Software Corporation

WORKSHOP 4

Creep of a Steel Tube


2/40

WS4-2




3/40

WS4-3



Model Description

In this exercise, we simulate the creep behavior of a stainless steel ovaltube pressurized at high temperature. Using symmetry, only half the tube

is modeled with plane strain elements.

The material constitutive behavior has the creep strain rate dependent

upon the stress level (Norton Creep). The material data has been fitted

with a power relation where the creep strain rate is expressed as:

Oval tube will bulge and become a completely circular over time, and will

rupture due to the large strains.


4/40


5/40

WS4-5



Exercise Overview:

Build the tube geometry and mesh from a session file. Create the Boundary Conditions.

Create the Pressure Load.

Create the Material Properties.

Create the Element Properties. Set up and Submit the job to analysis.

Evaluate the results.


6/40

WS4-6



Step 1: Open a New Database

Open a new database namedtube.db:

a. File > New.

b. Type tubeas File name.

c. Click OK.

d. Click OK to select MD

Nastran as the AnalysisCode. db c

a


7/40

WS4-7



When the session file is done the viewport will contain all

the geometry and the FE Mesh of a section of the tube.

Step 2. Run the Provided Session File

a

Run the provided session file.

a. Select File / Session /

Play.

b. Select

tube_model.ses as

the File name.

c. Click Apply.

(This action will run the

session file. Please do

not interrupt it.)

b

c


8/40

WS4-8



Step 3. Create the Symmetry Boundary Condition

Create the Symmetry Boundary

Condition.

a. Loads/BCs: Create /

Displacement /

Nodal.

b. EnterSymmetry_X as

the New Set Name.

c. Click on Input Data.

d. Enter for the

Translation.

e. Click OK.

d

e

a

b

c


9/40

WS4-9



g

f. Click on Select

Application

Region.

g. Select the Curve or

Edge icon.

h. Select the two edges

along the y-axis

i. Click Add.

j. Click OK.

k. Click Apply.

Step 3. Create the Symmetry Boundary Condition (Cont.)

f

k

i

j

h


10/40

WS4-10



Step 4. Create a constraint in the vertical (Y) direction

a. EnterFix_Y as the

New Set Name.

b. Click on Input Data.

c. Enter for theTranslation.

d. Click OK.

c

d

Fix a node in the Y direction, to prevent rigid

body motion

a

b


11/40

WS4-11



e. Click on Select

Application Region

f. Change the Select

Filter to FEM.

g. Select any node from

the y-symmetry line.

h. Click Add.

i. Click OK.

j. Click Apply.

Step 4. Create the Symmetry Boundary Conditions

gh

f

ie

j


12/40

WS4-12



Step 5. Create the pressure load

a. Loads/BCs: Create / Pressure

/ Element Uniform

b. EnterPressure as the New

Set Name.

c. Select 2D as Target ElementType

d. Click on Input Data.

e. Enter66 forEdge Pressure.

f. Click OK.

a

bc

d

e

f


13/40

WS4-13



g. Click on Select

Application Region.

h. Change the Select

Filter to Geometry.

i. Select the Edge icon.

j. Select the four inner

edges.

k. Click Add.

l. Click OK.

m. Click Apply.

g

Step 5. Create the pressure load (Cont.)

m

i

k

l

j

h


14/40

WS4-14



Step 6: Create the Material

To create an isotropic creep material:

a. Materials: Create Isotropic >Manual Input.

b. EnterStainless_Steel forMaterialName.

c. Click Input Properties.d. Enter21.4E6forElastic Modulus.

e. Enter0.3 forPoisson Ratio.

f. Click OK.

g. Click Apply.

a

de

f

a

b

c

g


15/40

WS4-15



Step 6: Create the Material (Cont.)

h. Click on Input Properties

i. Select Creep as Constitutive Model

j. Select MATVP forCreep Data Input

k. Enter4.E-24forCoefficient.

l. Enter4.51 forExponent of Stress.

m. Click OK.n. Click Apply.

h

i

j

k

l

mn


16/40

WS4-16



Step 7: Apply Properties

To apply properties:

a. Properties: Create

> 2D > 2D Solid.

b. Entertube for

Property Set Name.

c. Select Plain

Strain, and

Standard

Formulation.

d. Click Input

Properties.

e. Click the Select

Material icon.

f. Select

Stainless_Steel.

g. Click Ok.

a

a

c

d

b

ef

g


17/40

WS4-17



Step 7: Apply Properties (Cont.)

h. Click Select

Application

Region.

i. Click in the

Select Members

text box.

j. Select all thesurfaces.

k. Click Add.

l. Click Ok.

m. Click Apply.

h

i

k

l

m

j


18/40

WS4-18



Step 8. Set up Analysis: Analyze / Entire Model / Analysis Deck

Set up the non-linear Analysis job.

a. Analysis: Analyze / Entire

Model / Analysis Deck.

b. Entertube as the Job Name.

c. Open Solution Type.

d. Select Implicit NonlinearasSolution Type.

e. Click on Solution

Parameters

f. Check SOL400 Run,and

Assumed Strain

g. Click on Results Output

Formate

d

a

f

f

g

b

a

c


19/40

WS4-19



h. Select XDB

i. Select Print

j. Click OK.

k. Click OK.

l. Click OK.

h i

j

k

l

Step 8. Set up Analysis: Analyze / Entire Model / Analysis Deck (Cont.)


20/40

WS4-20



m. Click on Subcases

n. Click on Default under

Available Subcases

o. Enterstep_1_static as

Subcase Name

p. Click on SubcaseParameters.

q. Select Large

Displacement/Large

Strains.

r. Click on Load Increment

Parameters

q

n

o

pr

m



21/40

WS4-21



s. Select Fixed

t. Enter1as Number of

Increments

u. Click OK.

v. Click on Iteration

Parameters

v

s

t

u



22/40

WS4-22



w. Select Pure Full Newton

as Matrix Update Method

x. Enter4as Max # of

Bisections

y. Click OK.

z. Click OK.

z

w

x

y



23/40

WS4-23



aa. Click on Output Requests

bb. Click on Standard Output

cc. Select Element Strains

dd. Select Non-Linear Stress

ee. Click OK

ff. Click OKgg. Click Apply

bb

cc

dd

eeff gg

aa



24/40

WS4-24



hh. Enterstep_2_creep as

Subcase Name

ii. Select Creep as Analysis

Type

jj. Click on Subcase

Parameters.kk. Select Explicit Creep as

Procedure

ll. Click on Load Increment

Parameters

hh

ii

jj

kk

ll



25/40

WS4-25



mm. Select Adaptive Creep

nn. Enter17.35as Suggested

Time Increment

oo. Enter3.47E6 as Total Time

pp. Enter9999as Max. #

Number of Increments

Allowed

qq. Click OK.

rr. Click OK

mmnn

oo

pp

qq

rr



26/40

WS4-26



ss. Click Apply

tt. Click Cancel

ss tt



27/40

WS4-27



uu. Clickon Subcase Select

vv. Selectstep_1_Static, and

Step_2_Creep

ww. UnselectDefault

xx. Click OK

yy. Click Apply

uu

vv

ww

xx

yy



28/40

WS4-28



Step 9. Edit the exported input file

Edit the file, tube.bdf (be sure to save it when done):

a. Replace the following lines :

by

MDLPRM,REALT,1

MDLPRM,NLDIAG,10

NLMOPTS,CREEP

,LRGSTRN,1,

NLPARM,1,1,1.e-9,PFNT, ,40,PV,

,0.01,0.01,

NLPARM,2,200000,17.35,PFNT,,40,PV,YES

,0.01,0.01,

,10

NLADAPT, 2

, STEP, 0.1, 1.5, 1.0-8, 0.5, 999999, 6, 1.2

, , 0, 2.-4,

, CREEP, 0, 0.5, 1.0, 0.05

PLPLANE, 1, 1

PSHLN2, 1, 1, 1, 1.0,

, C4, PLSTRN, L


29/40

WS4-29



Step 9. Edit the exported input file (Cont.)

b. Replace the following line :

by :


30/40

WS4-30



Step 10. Run MD Nastran

Run MD Nastran with file, tube.bdf

a. Double Click on the MD Nastran icon in the desktop

b. Select tube.bdfas input File name

c. Click Open

d. Click Run (job might take 10+ minutes to run)

a

b

c

d


31/40

WS4-31



Read (Attach) results.

a. Access Results / Attach XDB /

Result Entities.

b. Click on Select Results File ..

c. Selecttube.xdb

d. Click OK

e. Click Apply.

Step 11: Access the nonlinear Results

aXV

c

d

b

e

a

St 12 Vi R lt


32/40

WS4-32



Step 12: View Results

To create a fringe results plot:

a. Results: Create > Quick Plot.

b. Select thefirst Results case

c. Select Logarithmic Strains, as the Fringe

Resultd. Select Displacements, Translational.

e. Click the Display Attributes icon.

f. Change the Scale Interpretation to True Scale.

g. Click Apply.

f

g

a

a

b

c

d

e

St 12 Vi R lt (C t )


33/40

WS4-33



Step 12: View Results (Cont.)


34/40


35/40

Step 12 Vie Res lts (Cont )


36/40

WS4-36



k. Select thelast Results case

l. Select Logarithmic Strains, as the Fringe Result

m. Click Apply. k

l

m


Step 12: View Results (Cont )


37/40

WS4-37






38/40

WS4-38



n. Select Cauchy Stresses as the Fringe Result

o. Click Apply.

n

o




39/40

WS4-39




Step 13 Quit Patran


40/40

WS4-40



Step 13. Quit Patran

Documents

Tube Creep