Exhaust Analysis Optimization

8/13/2019 Exhaust Analysis Optimization

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Agenda

DesignstatusAssemblyDOC/DPF

BracketsSCRMufflersystem

Durability StatusDOC/DPF FEA Calculations

Risk analysisProcedureInitial bracket proposal

QuestionsDesignWorksplitTiming


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EXHAUST SYSTEM LAYOUT FOR SCDC

DOC & DPFASSEMBLY

SCR ASSEMBLY REAR MUFFLERASSEMBLY

INTMD PIPE


4/27

Substrate DOC

(5.66x3)

Support Mat DPF

Support Mat DOC

Case

Substrate DPF(5.66x6)

Wire Mesh Ring

DOC & DPF ASSEMBLY


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DOC & DPF ASSEMBLY

Brackets on possible fixing points

Flange Turbo

Pipe Inlet

Cone Isolation

Cone Inlet

Pipe Outlet

BracketTurbocharger

Bracket DPF No. 1

Bracket DPF No. 2

Console DPF

Flange Outlet

Cone Outlet


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NEW TURBOCHARGER BRACKET

SUPPORT BRACKET Turbocharger


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SCR ASSEMBLY

Flange Inlet

Bellows Flexible

Console

Pipe Inlet No.1

Injector Unit

Mixer Pipe Inlet No.2

Cone Inlet

CaseCone Outlet

Hanger Clamp

Pipe Outlet

Bracket

Isolators need to be finalized


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Dosing Unit and Mixer

Casting

Mixer

Isolation Halfshell

ffl bl


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Muffler Assembly

Pipe Inlet

Muffler

Tail Pipe

Hanger No. 1

Hanger No. 2

Hanger No. 3

Hanger No. 4


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Temp. Sensor 1NOx Sensor. 1

Temp. Sensor 2

Temp. Sensor 3

NOx Sensor 2

Sensor Positions(VALEO Temperature Sensors)

Pressure Pipes

O2 Sensor Boss


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Risk analysis

Legends

Evaluation

Hanger forces:

Exhaust balance:

Load on tubes and hangers:

Hanger displacements:

Load on tubes and hangers:

Static

Road Load

Dynamic

Resonance load

Green, current design OK,

Yellow, check current design with measurements.Design changes might be necessary.Standard solutions und engineering actions willsolve the problems.

Red, current design NOT OK,Design changes are necessary.Increased engineering effort is necessary.


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General remarks:This FE analysis is not correlated with measurement data.

All dynamic amplitudes (displacement, stress, strain) may differ in reality. All dynamic amplitudes are computes with assumed modal damping. Real damping will be in the range of 0,2 to 5 %.This has a strong impact on the amplitudes. Damping cannot be predicted

Frequencies are computed with a higher confidence. All static analysis is highly reliable.

This report should be taken as a risk analysis to address the engineers attention to potential critical areas in the

exhaust system. Investigation should be proceeded more detailed in future with additional analysis likemeasurements.

Alternatively a correlation of the FE analysis with measurement from a running mode analysis is possible to reducethe Amplitude error below 20%.

Good Evaluate Critical

Hot End Welding, Notch Factor 2


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Risk analysis DOC-DPF assemblyDynamic analysis, without any bracket

Excitation:

-excitation_01mm.bdf

Other details

-Dynamic: Temp 550 C

-Damping: 2%

Excitation Node

Flex end is fixed


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Frequency[Hz]

Max. stress[MPa]

49.8 32.3

52.5 32.6

148.6 322.9

160.1 281.3

Risk analysis DOC-DPF assemblyDynamic analysis, resonance frequency table

1. Modeat 49.8 Hz

2. Modeat 52.5 Hz


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Frequency[Hz]

Max. stress[MPa]

49.8 32.3

52.5 32.6

148.6 322.9

160.1 281.3

Risk analysis DOC-DPF assemblyDynamic analysis, resonance frequency table

3. Modeat 148.6 Hz

4. Modeat 160.1 Hz


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1. Modeat 49.8 Hz

2. Modeat 52.5 Hz

Risk analysis DOC-DPF assemblyDynamic analysis, stress plots


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3. Modeat 148.6 Hz

4. Modeat 160.1 Hz

Risk analysis DOC-DPF assemblyDynamic analysis, stress plots


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Dynamic load caused by engineexcitation

Manifold and Turbo Charger:Without Turbo BracketCompact Design but

Eigenmode at 49,8 and 52.5 Hz caused byTurbo rotation.With Turbo BracketMaybe rotation will be reduced, higherresonance frequency occur

Inlet pipe and cone:

Outlet pipe and cone:

Risk analysis DOC-DPF assemblyDynamic analysis, Eigenmodes


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Eigenmode at 49,8 Hz caused by Turborotation.With Turbo BracketMaybe rotation will be reduced, higherresonance frequency occur

Inlet pipe and cone:Eigenmodes at 49.8 and 52,5 HzStress values borderlineEigenmodes at 148.6 and 160.1 HzStress values very high

Outlet pipe and coneShort outlet pipe no significant stressoccur

Risk analysis DOC-DPF assemblyDynamic analysis, stress at 148 Hz

FEA deliver at 148 Hz an Eigenmode with high stress at 322 MPa. An additional bracket is necessary !

Ri k l i DOC DPF bl


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Risk analysis DOC-DPF assemblyDynamic sensitivity analysis

The resonance behavior is influenced greatly by inlet cone and inlet pipe.

Sensitivity analysis on E-Module Mod e-1 (49.83 Hz )

6.05

2.30 2.19

0.880.52

0.26 0.15

4.34

0

1

2

3

4

5

6

7

C O N E

_ I N L E

T

P I P E_

I N L E T

M A N I F

O L D

T U R B

O_ 0 1

F L A

N G E_

M A N I F

O L D

C A S E

P I P E_

O U T L

E T

C O N E

_ O U T

L E T

CONE_INLET

PIPE_INLET

MANIFOLD

TURBO_01

FLANGE_MANIFOLD

CASE

PIPE_OUTLET

CONE_OUTLET

Ri k l i DOC DPF bl


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Risk analysis DOC-DPF assemblyDynamic sensitivity analysis

Increasing cone thickness doesnt lead to higher resonance frequency forthe 3rd and 4th mode.

Mode[No]

Frequency[Hz]

Max. stress[MPa]

1 53.6 29.48

2 57.4 25.74

3 149.5 171.1

4 161.7 258.6

Thickness of the KAT inletcone

1.2mm 2.0mm






Ri k l i C ld d


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StaticHanger forces:Static Hanger forces expected to be OK

System balance:Hangers are good distributed and expected

to be good balanced.

Road loadLoad at pipes and hangers:Exhaust is not heavy no high load willoccur.3rd Hanger at muffler maybe should bereplaced at the connecting pipe. Ifreplacement is possible, FEA will give theright answer.

DynamicHanger displacements:Long and bended tubes may show highdisplacements.

Load at pipes and hangers:High displacements leading to high stress atpipes.

Decoupling:Flexible tube 180 mm build in along rolldirection.

Soft flex in front of Stiff hanger bridge willdecouple engine rock.Long and soft flex will decouple the engineexcitation from cold end. Also decouple thecold end mode from the hot end.

Risk analysis Cold end

Bracket Optimization Process


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Topology Optimization

FE Analysis of Eigenmodes of bare system

(w/o brackets)

Evaluate possible fixing points andpackage constrains

Initial design of brackets on allreasonable fixing points

FEA Calculation (Bracket matrix)

Decision of bracket concept

Redesign brackets (optimization)

FEA Calculation

CAE Optimized Brackets

Bracket Optimisation Process


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Bracket Matrix

Turbo I Turbo II DOC/DPF 1 DOC/DPF 21 x x x x2 x x x3 x x x4 x x x

5 x x x6 x x7 x x8 x x9 x x

Bracket

Topology Optimization


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Thermal strain

Stiff BracketSoft Bracket Stiffness Bracket

Strain

Dynamic strain

Physical behaviour lead to target conflict:Thermal load requires soft bracketsDynamic load requires stiff brackets

DOC & DPF ASSEMBLY


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Brackets on possible fixing points

DPF Bracket 1Near Engine outlet (less thermalexpansion)

can be stiffer in Z-direction Needs additional fixing points on engine

Turbo bracket 2Well known conceptSoft in thermal expansion directionM&M scope of supply

DPF Bracket 2Best position to hold Mode 1+ 2 Needs to be soft in thermalexpansion directionMounting difficult

Turbo bracket 1M&M ProposalM&M scope of supply

Exhaust Analysis Optimization

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