Qingzhong Li Dong Wei Bill Moser Scott Thompson Don Sit

Caterpillar Inc.

TMF Lite Process Development

SCC May, 2012

Table of Contents

1. Project Background / Objective

2. TMF Lite Model Development /Verification

• Lite Model Development

• Abaqus User Subroutine

• Verifications

3. Project Summary

1 Background/ Objective

TMF --- Thermal Mechanical Fatigue analysis (mainly used in exhaust manifold)

Center section

Time (s)t2t1

Rated gas temp

t3 t4

Idle gas temp

Gas temperature

Cylinder Head

Exhaust ManifoldTurbo-housing

(full load)

Typical Test Cycle

C13 2004 High-Mount

Temperature profiles on the thermocouples

0

100

200

300

400

500

600

700

800

900

1000

1100

0 200 400 600 800 1000 1200

Time(Sec)

Tem

pera

ture

(K)

tc11

tc10

tc9

tc8

tc7

tc6

tc5

tc4

tc3

tc2

tc1

Temperature cycles at different locations

Center section

Time (s)t2t1

Rated gas temp

t3 t4

Idle gas temp

Gas temperature

Cylinder Head

Exhaust ManifoldTurbo-housing

(full load)

Typical Test Cycle

Time (s)t2t1

Rated gas temp

t3 t4

Idle gas temp

Gas temperature

Cylinder Head

Exhaust ManifoldTurbo-housing

(full load)

Typical Test Cycle

C13 2004 High-Mount

Temperature profiles on the thermocouples

0

100

200

300

400

500

600

700

800

900

1000

1100

0 200 400 600 800 1000 1200

Time(Sec)

Tem

pera

ture

(K)

tc11

tc10

tc9

tc8

tc7

tc6

tc5

tc4

tc3

tc2

tc1

Temperature cycles at different locations

t4t0 t8

Background/ Objective

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•Overview of Standard TMF Process

CFD Analysis

-Create CFD model

-Run Thermal Cycle Analysis

-CFD/FEA –Post Process

FEA thermal stress Analysis

-Create FEA model

-ABAQUS Assembly/ Verify Contacts

-Thermal stress analysis

Fatigue Analysis

-Convert Stress format (skin

mesh result)

-Run COBRA for TMF

- Post Processing

Project Background / Objective

Multiple Tier4a manifold designs need to assess the

structural integrity quickly during the design stage.

Challenges of New HPL EGR Strategy for Tier4i

…

…

Validation Challenges of New Designs for Tier4i

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More than 6 configurations had to use totally new manifold designs

More configurations to analyze.

Limited validation time.

Project Objective

This study is to develop a simplified heat transfer and TMF life analysis procedure which can

simplify the analysis process and achieve reasonable results at the same time.

This simplified procedure sacrifices overall accuracy for analysis speed and is intended to

complement the full version of TMF.

2. Lite Model Development

Full CFD

(Fluent)

Full

Structural

(ABAQUS)

Lite transient heat transfer

analysis model (ABAQUS)

Lite structural model (ABAQUS)

Same mesh

Lite Model –Initial Iterations

•Outer surface: Htc=0.05 * head-manifold: htc=1.0

•Same as internal surface/

or no BC

Internal surfaces: constant htc 0.70

*sfilm,amplitude=temp_amp_2, film amplitude=htc_int_long2

internal_long_surf_b, F, 127,0.70

Step Time (s)t2t1

Full load htc

HTC

t3 t4

Idle load htc

Abaqus usage:

Htc unit: mw/mm^2-C

Temperature Comparison

Idle temperature contour from CFD

The goal is to map CFD steady results

with a set of heat transfer BC

CFD

ABAQUS simplified model

C13 2004 High-Mount

Temperature profiles on the thermocouples

0

100

200

300

400

500

600

700

800

900

1000

0 200 400 600 800 1000 1200

Time(Sec)

Te

mp

era

ture

(K)

tc11

abaqs-tc11

abaqus-v61

v13

v14

v15

v17

v18

v19

t0 t4 t8

User Subroutine film.f Development

Advantage: define different thermal boundary conditions

without extra definitions of surfaces (one surface definition but

different htc and sink temperature values at different locations)

All cylinders have

1 exhaust pulse

every 2 revs of the

engine.

This area sees 3

exhaust pulses every 2

engine revolutions.

Assume this area gets

the “high” HTC value.

This area sees 2

exhaust pulses every 2

engine revolutions.

Physics says this area

HTC “should” be ~2/3

of the “high” value.

The head ports see 1 exhaust pulse

every 2 engine revolutions. Physics

says this area HTC “should” be ~1/3

of the “high” value.

Step Time (s)t0

Full load htc

HTC

Idle load htc

t1 t2 t3 t4

Inputs to Film User Subroutine

- Coordinates of nodes at port interfaces

A1B1

C1

A3

B3

C3

Head Flange Surface 3

A2

B2

C2

Abaqus usage: *sfilm

internal_long_surf, FNU, 127, 0.61

This should be the

high htc of the port

HTC Verification using ABAQUS

User Subroutine UVARM

** It was verified that the ports were correctly divided into

different regions and assigned with correct htc.

Temperature Difference

between CFD and Lite Models

-20

0

20

40

60

80

TC 1

TC 3

TC8

TC11

top

edge

radi

usT

em

pe

ratu

re D

iff

(C)

old- h=0.70

New - h=0.61

user subroutine

Temperature Comparison

between Full Model and

Lite Models

TC10TC9

TC6, 7, 8

TC4, 5

TC2

TC3

TC11

TC1

TC10TC9

TC6, 7, 8

TC4, 5

TC2

TC3

TC11

TC1

Top edge

Radius

TC3

Thermal Couple and Other

Critical Locations Used for

Comparison

TC1

TC11

TC3

TC3

L2

L3

L1

Left View

R1

R2

R3

Right View

T3

T1T2

T4

Top View

B3

B5

B4

B1

B2

Bottom View

H1 H2

Head Flange View

B6

TMF Life Comparison between Different Models and Full CFD Results

TMF Comparison Locations

Lite/Full TMF Life Comparison

Most data fall in the range of one order of magnitude

More than 70% of data are below Full TMF results; the data which exceed full TMF results are

less than 2x of the CFD results, therefore the model is generally conservative

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

Cycles - Full CFD

Cycle

s -

Lit

e

Lite Analysis -User subroutine

10x2x

0.5x

0.1x

4. Project Summary

Back to Table of Content

A TMF Lite Procedure has been developed and verified; Its

advantages / limitations defined;

Lite Process significantly reduces the TMF analysis time to 3 ~ 5

working days (Transient FEA + Stress FEA +TMF) from about 2~3

months for the full TMF;

This process has been incorporated as an important part of the

overall manifold validation strategy;

TMF Lite procedure has been used in many Tier4a exhaust

manifold new designs; More than 20 new designs were evaluated;

Questions?

Thanks!