fenet majorca march2004 dle sanvicente

8/4/2019 FENET Majorca March2004 DLE SanVicente

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FENET Meeting, WS7, DLE Session Mallorca, 25 March 2004

Creep Sim ulat ions w i t h ABAQUS:

Super Plast ic Forming

PRINCIPIA Ingenieros ConsultoresMadrid, SPAIN

Jose L. San Vicente

http://www.principia.es

FENET Durability and Life Extension

FE Issues Related to Creep and Viscoelasticity

Mallorca, 25 March 2004

FENET Workshop - Finite Element Analysis of Creep and Viscoelasticity

Majorca, Spain

25-26 March 2004

CREEP Simulations with ABAQUS

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Tab le of con ten t s

Superplastic forming

CREEP models

SPF - FE analysis

Examples

Conclusions


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CREEP Sim ulat ions w it h ABAQUS:

Super P last i c Forming

1. Super plast ic forming (SPF)


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Super Plast ic Formi ng (SPF) (1)

Sheet forming process

large elongations are reached in the material

limited to materials with Superplastic properties

Complex geometries

Goals

Forming process with no (or little) damage to the components

Reduce the number of components

Reduce the number of joints

Aerospace applications


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Page 5


Aluminium alloys (Al, Ti, V, ...)

Expensive materials Superplastic behavior only in a superplastic range

High Temperature: 900 C

Low strain rate: 10e-5, 10e-3

Large deformations + low strain rate = long times

Set-up


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The industrial production is constrained by:

Productivity: Forming the components as fast as possible

Superplastic behavior only for low strain rates: as slow as possible

Facilities: maximum pressure

Goals:

Forming as fast as possible, but remaining in the SP range

Find the appropriate load history


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2. CREEP models


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CREEP m ode ls (1)

Material behavior


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CREEP m ode ls (2)

Creep modeling

Primary creep: non-proportional response

Secondary creep: proportional

Tertiary creep: hardening

Unspecified Creep: Secondary creep

Wider range

Predominant

Easy to model


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CREEP m ode ls (3)

Modeling of non-proportional creep

Standard laws

Time law

Strain hardening

More sophisticated laws

B. Zhang et al.


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3. SPF: FE Analysis


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Finite element modeling of forming

Rigid dies

Mesh of the blank with shell or brick elements

Static analysis

No inertia forces

Uniform pressure on the sheet surface

Contact: friction, finite sliding

Coupling of models (elasticity, plasticity, )

SPF: FE Ana lys is (1)


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Additional features for FE in SPF

Creep governs the response

Implicit vs Explicit integration

Need of a smooth strain rate

Time stable limitation in explicit

Too restrictive, even with mass scaling

Implications: deal with contact, large models, in implicit

Unknown load history

Solution dependent need of adaptive loading

Constraint 1: Strain rate in SP range Constraint 2: Pressure at the manufacturing facilities


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FE Results

Formed geometry

Shape

Thickness

Load history

Comparison between

Target strain rate

Actual strain rate

Ciclos de presin

0.001.002.003.004.005.006.007.008.009.00

10.0011.0012.0013.00

14.0015.00

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0

Tiempo (min)

Presin

(bar)


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Some difficulties

Material properties

Owned by the manufacturers

Testing very expensive

Implicit approach

Large models and small integration time

Contact with finite sliding

Round-off in the creep equation

Even with double precision




4 . Ex a m pl es


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Page 17

Case 1

Calibration example

Calibration of Inconel 718

Too complex for library material

User routine CREEP

Uniaxial testing


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Case 1

Validation with actual case: axisymmetric component

FE-Model

Testing


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Page 19

Case 1

Thickness reduction

Succesfully used in production


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Case 2

Slat


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Analysis of control sections

Inital package of 4 sheets

High temperature: Welding of sheets where are in contact Easy joints: avoids rivets, ... Welding inhibitor in the rest

Case 2


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Results

Pressure-time

Map of thickness

Case 2

0

5

10

15

20

25

0.0 20.0 40.0 60.0 80.0 100.0


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Case 3 Study o f the nose in the des ign o f one s la t

Last phase of the forming


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Three dimensional simulation

Case 4 SPF of a spoi ler


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5.- Conc lus ions


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SPF uses CREEP for manufacturing purposes. Complexgeometries with no joints are good candidates in aerospaceindustry.

SPF includes all the features in conventional sheet forming, butthe pressure is solution dependent. This requires adaptive loadapplication.

SPF implicit approach has to face large models and intensivecontact. This needs a robust numerical tool.

Some examples of advanced SPF simulation by PRINCIPIA havebeen shown. They have been done with ABAQUS/Standard.

Conclus ions

fenet majorca march2004 dle sanvicente

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