weld distortion optimisation using hyperstudy

25/06/14

European Altair Technology Conference

Munich 2014

Weld Distortion Optimisation

©2012 GESTAMP 1

Altair Technology Conference 2014– Weld Distortion Optimisation

• Zidane Tahir : Design Analyst – Gestamp Chassis

• Inverse Identification in weld Distortion using

HyperStudy

• Weld Distortion Optimisation using HyperStudy

Introduction

NORTH AMERICA

8 Production Plants

SOUTH AMERICA

10 Production Plants

EUROPE


RUSSIA

3 Production Plants

ASIA


A GLOBAL COMPANY

©2012 GESTAMP 2


Gestamp Chassis

©2012 GESTAMP 3


Gestamp Chassis

©2012 GESTAMP 4


Weld Distortion is the physical warping of a part, induced by the heating and

subsequent cooling caused by the welding process.

TSB Project No. TP/TP/DSM/6/1/16131 – 2010 Roger O’Brien

Macro section of butt weld, (shown in Figure 6.1.17) in 2.5mm thick Xf350

material, weld produced using LSND process

©2012 GESTAMP 5


Weld Distortion

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WELD DISTORTION ANALYSIS AND CORRELATION

Inverse Identification using HyperStudy

©2012 GESTAMP 7


Weld Distortion Analysis – Modelling Method and inverse identification

𝐷𝑖𝑠𝑡 = 𝑙0𝛼1∆𝑇 𝑊𝑒𝑙𝑑_𝑠𝑒𝑡 + 𝑙0𝛼1𝜷∆𝑇 𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡_𝑠𝑒𝑡

Weld_set

Adjacent_set

β is the temperature diffusion factor in adjacent elements affected by heating

β is identified using inverse method implemented in HyperStudy

𝐹𝑖𝑛𝑑 𝛽

min 1

2𝐷𝑖𝑠𝑡𝐹𝐸𝐴 − 𝐷𝑖𝑠𝑡𝑇𝐸𝑆𝑇

12

The advantage of this

method is to avoid thermal

transient time consuming

calculation

©2012 GESTAMP 8


Weld Distortion Analysis – Correlation

Optimum

β= 0.57

Dist = 8.08 mm

Sequential Quadratic Programming has

been used successfully to obtain the

optimum

©2012 GESTAMP 9


“REDUCE THE DISTORTION OF A PART WITHOUT ADDING COST OR

SIGNIFICANTLY ALTERING PERFORMANCE.”

©2012 GESTAMP 10


Weld Optimisation (Stiffness/Durability)

Fully Welded

Remove weld causing significant

distortion

Weld Removal Optimisation

Weld Sequence Optimisation

Manage distortion through additional process and design

features

Reduce weld and meet structural constraints

(hope for reduced distortion)

Arbitrary removal based on reducing

magnitude of distortion

Optimum solution Combine removal

and sequence

First true optimisation based on distortion

Fine tuning of sequence to further

reduce distortion

Weld Distortion Optimisation Evolution

©2012 GESTAMP 11


• Front Subframe tower case study

• Towers susceptible to distortion due

to their geometry

• Tolerance regained by having “float”

designed into the components

• Objective – reduce distortion

without changing geometry.

Case Study

©2012 GESTAMP 12


WELD REMOVAL OPTMISATION

©2012 GESTAMP 13


• Topology Optimisation Identified critical

welds for stiffness/durability

performance (Optistruct).

• Weld lengths are split to 30mm

sections and given generic group

names (Weld01, Weld02, etc) using

automated scripting in HyperMesh

Weld Removal Optimisation

• For this study we have 30 weld sections

• 10 critical sections identified by

Optistruct

• 20 design variables

©2012 GESTAMP 14


Key Objective Values

Extraction Job Queue

Create ABAQUS Deck

Generate Welding List

(ON/OFF)

Generate Deck Geometry

Optimisation Algorithm

Material + Base Geometry etc.

Full Weld Model

Run ABAQUS

Deck

Results Cluster

Initial Conditions

(ALL WELDS ON) PROCESS IS

GENERIC

Hyperstudy

SciLab

Optimal Solution!

Weld Removal Optimisation – Process Flow

©2012 GESTAMP 15


Case Study

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Weld removal optimisation – Major iteration 1

©2012 GESTAMP 21


3,00E-01

4,00E-01

5,00E-01

6,00E-01

7,00E-01

8,00E-01

9,00E-01

1,00E+00

0,036 0,0362 0,0364 0,0366 0,0368 0,037

Ind

uc

ed

Dis

tort

ion

(m

m)

Tower Displacement Under Loading (mmkN-1)

Tower Case Study Pareto Frontier

Design iterations Pareto front

Pareto Frontier

©2012 GESTAMP 23


Key Objective Values

Extraction

Job Queue

Create ABAQUS Deck

Utilising *modelchange

Generate Weld Sequence Discrete

Variables

Generate Deck Geometry

Optimisation Algorithm

Material + Base Geometry etc.

Full Weld Model

Run ABAQUS

Deck

Results

Cluster

PROCESS IS GENERIC

Hyperstudy SciLab

Optimal Solution!

Generate Welding

Sequence

Initial Conditions

(PROCESS ORDER)

Weld Sequence Optimisation – Process Flow

©2012 GESTAMP 32


Original

design

Weld Removal

Optimised design

Weld Sequence

Optimised design

Value Reduction Value Reduction

Weld distortion (mm) objective 1.24 0.54 56% 0.09 93%

Stiffness (MNmm-1) constraint

target (27.4) 30.1 27.4 0 27.4 0

Max Stress (MPa) Constraint

target (280MPa) 280 234 16% 234 16%

Weld length (mm) output 870 650 25% 650 25%

Total Robot head

movement (mm) output 1290 1140 12% 2490 +93%

Case Study- Results

©2012 GESTAMP 34


• HyperStudy can be used to effectively reduce weld distortion.

• Sequence algorithm generation to be enhanced to avoid

repeatable sequences

• Gradient based optimisation techniques apply well to weld

removal problems however their applicability in weld sequencing

problems is limited where global search algorithms are more

effective.

• The platform developed is generic and applicable to any weld

distortion project without any adaptation.

• HyperStudy allows a flexible, multi-platform approach for

optimisation management and is a good tool for solving this

optimisation problem.

Conclusions

weld distortion optimisation using hyperstudy

Engineering