cummins gt crank

8/8/2019 Cummins Gt Crank

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All information contained in this document is confidential and cannot be reproduced or transmitted in any form or by any means, electronic or mechanical, for anypurpose, without the express written permission of Gamma Technologies, Inc. © 2007 Gamma Technologies, Inc.

Validation, Benchmarking and Deployment of GT-CRANK at

Cummins

Ilya PiranerCummins, Inc.

J. Rodriguez, M. Okarmus, S. Erogbogbo, R.Keribar

Gamma Technologies




• 2+ year project, now near completion

• GTI Objectives – Team with a leading industrial partner with expertise/data

– Explore fast analysis methods for crankshaft durability

analysis• Cummins Objectives

– Unify crankshaft design analysis procedures in a singletool

– Migrate from in-house to commercially supported software

– Integrate with other GT-SUITE elements (GT-POWER,GT-VTRAIN) used at Cummins

Joint GTI-Cummins Development Project




Cummins Perspective & Background

• Since late 90s the Company strategy has been to partnerwith leading software development / consulting companies inorder to replace in-house simulation codes with a more

efficient commercial software utilizing latest technologies.

• In 2005 a DFSS project has been run to “Determine voice of the customers and Identify commercial tool for concept/design level crankshaft and bearing analysis ”

• The primary customers voice was “Improve ease of use

and efficiency while preserving current tool functionality and speed ”.

• As a result of the project technical requirements have been

developed and a number of competitive products have beenexamined.




Cummins: Evaluation of Tools

Functional Product Requirements Target Range (with Units) In-house Tool 1 GT

ESW tasks supported 100% 100 90 100

Time to run single analysis 2 min 2 2 2

Tech. Documentation and Support (ToolFunctionality Covered in Help)

95% 75 90 95

Set up Time 4 hours 4 4 4

Integrated Block Bending Analysis 100% Configurations 100 0 100

Integrated Balance Analysis 100% Configurations 0 0 100

Platform Independent GUI with Help 2 0 2 2Time to Learn 2 days 1 3 2

Parametric Study 5 parameters/3 levels 1 3 5

Optimization tool y/n N Y Y

Adequate Physical Models 10 (scale) 9 5 9

PTO Tool 10 (scale) 8 0 9

IACS (M53) Analysis y/n Y Y Y

Postprocessing Time 10 (scale) 3 6 9

Overall Score 621 606 990




Joint GTI-Cummins Development Project

• Project Scope – Absorb existing Cummins crankshaft analysis techniques into GT-

CRANK

– Benchmark and validate GT-CRANK against Cummins in-housetools

– Deploy GT-CRANK at Cummins worldwide

• GT-CRANK models affected(*

indicates new feature)

– Freq. domain torsional analysis (2005-2006)

– Crankshaft Bending (2006)*

– Bearing oil films (2006)

– Stresses & fatigue (2006-2007)* – Outputs and post-processing (2005-2007)

• Most objectives met by the initial v6.2 release

• Remainder in GT-CRANK v6.2 Builds 6, 8




Project Objectives

• GTI

– Team with a leading industrial partner with expertise/data – Explore fast analysis methods for crankshaft durability

analysis

• Cummins – Unify crankshaft design analysis procedures in a single

tool

– Migrate from in-house to commercially supported software

– Integrate with other GT-SUITE elements (GT-POWER,GT-VTRAIN) used at Cummins




Cummins HD I-6 Diesel Engine Model




Cummins V-8 Short Block Engine Model




Torsional Vibrations

GT-CRANK v6.1:• Time and frequency-domain (free + forced) TV

• General, cranktrain + attached components

Additional Features:

• Frequency-dependent non-linear damping

• Enhanced and very comprehensive outputoptions




Comparison to Cummins Torsional Vibration Analysis

I-6 Engine Speed Sweep

Power Loss in Torsional DamperDisplacement Amplitude vs. Speed:

Orders 1.5, 3.0, 4.5 and 6.0




Journal Bearing Oil Films

GT-CRANK v6.1:

• HD-Impedance solution, Orbit, MOFT, Friction

Now:

• HD-Mobility solution option• Oil flow modeling and thermal balance

• Coupled crank bending + bearing oil film

solution• Effect of oil grooves and holes

• Option for a simplified power loss/flow model

(Orlov)




Comparison to Cummins V-8 Main Bearing Orbits – 4000 RPM

0

20

40

60

80

100

120

140

160

180

200

1 2 3 4 5

P O F P ( M p a

)

Main Bearing Number

Peak Oil Film Pressure

GT

Cummins

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1 2 3 4 5

M O F T ( µ m

)

Main Bearing Number

Minimum Oil Film Thickness

GT

Cummins




CrankShaft Bending

GT-CRANK v6.1: No crankshaft bending model

Now:

• Crankshaft bending by 3D Beam-FE

formulation• Beam cross-section properties from

compliances of crankthrow 3D FE model

• Quasi-static or dynamic solution• Coupled to journal bearing oil films, or

springs & dampers




Equivalent 3D Beam FE Model

Elements

Nodes

3D crankthrow solid FE

model compliances usedto automatically createequivalent 3D Beam FEmodel

Compliance for 3 load cases3D FE Analysis

S o l u

t i o n f o r b

e a m

s e c t i o

n p r o p

e r t i e

s




Comparison to Cummins V-8 Main Bearing Loads – 4000 RPM

Maximum Bearing Force

0

10000

20000

30000

40000

50000

60000

70000

1 2 3 4 5

Main Bearing Number

F o r c e ( N )

GT

Cummins

Crank Bending Animation with Contours of Mx




Simplified EFR Stress/Fatigue Analysis

• Maximum stress/moment ratios for journal & crankpinfillet from 3D FE analysis of throw under in-planepositive and negative crankpin loads only, input to GT-

CRANK.• Instantaneous concentrated stresses recovered in GT-

CRANK

• EFR Stress calculated and fatigue “Acceptability”

predicted EFR= amp

/(1- mean / tfs

)

Acceptability = EFR.limit / EFR




Main Fillets Stre ss

0

50

100

150

200

250

300

350

400

1 2 3 4 5 6 7 8

Web #

S t r e s s ( M p a )

GT

Cummins

Pin Fillets Stre ss

0

50

100

150

200

250

300

350

1 2 3 4 5 6 7 8

Web #

S t r e s s ( M p a )

GT

Cummins

Comparison to Cummins V-8 Web Fillet EFR Stresses I-6 1600 RPM V-8– 4000 RPM

Crankpin

Fillet

Journal

Fillet

Web 1L -1.94 -0.98

Web 1R -4.69 -3.81

Web 2L -3.04 -2.48

Web 2R -4.01 -3.21

Web 3L -3.48 -2.81

Web 3R -0.78 -0.93

Web 4L -1.74 -0.85

Web 4R -1.91 -1.94

Web 5L -2.98 -2.43

Web 5R -1.91 -1.37

Web 6L -4.66 -3.45

Web 6R -0.95 -0.93




EFR Stress/Fatigue

by Unit Load FEA Stress Recombination • Technique developed by Cummins (Piraner,

2002)

• Embedded & automated in GT-CRANK (v6.2Build 8)

• More-comprehensive alternative to simplifiedEFR stress/fatigue analysis option:

- Does not rely on prior determination of maximum nodal FEA stress-

to-moment ratios in stress concentration zones- Considers the entire and true composite dynamic load stress field,

reconstituted from stress fields for all unit loads

• Rigorous coupling of GT-CRANK analysis + 3DFEA




Unreliability or Acceptability Calculationfrom Stress and Strength Variances

EFR Stress/Fatigue Methodology II

EFR,max,m,s= max

i(EFR,j,m,s

)

EFR,max,s= maxm (EFR,max,m,s)

EFR,max = max j (EFR,max,,s)

EFR,j,m,s= amp,j,m,s

/(1- mean,j,m,s / tfs

)

Maximum EFR Stress in StressConcentration Zone, Crankthrow and

Crankshaft

EFR (Equivalent Fully-Reversed) Stress

Cyclic Maximum, Minimum, Mean &Amplitude of SPS and Stress Tensor.

Von Mises “amplitude” stress*

Sorted Principal Stress (SPS) j,k,m,s

Unit Load Stress Superposition(Instantaneous Stress Tensor)

i,j,k,m,s= nFk,nC n i,j,k,m,s

AEFR

= 1-UREFR

* “Von Mises” Stress based on stress cyclic amplitude

tensor

max,j,m,s= max

k ( j,k,m,s)

min,j,m,s= min

k ( j,k,m.s

)

mean,j,m,s=avg

k ( j,k,m,s

)

amp,j,m,s = (max,j,m,s- min,j,m,s)/2




BackPin fillet

BackJournalFillet

Comparison to Cummins EFR Stress & Acceptability

Four stress concentration zones considered

Front JournalFillet

FrontPin fillet

FRONT

JOURNALFILLET

BACK

JOURNALFILLET

FRONT PINFILLET

BACK PINFILLET

% Diff % Diff % Diff % Diff

Max. Component Stress 0.86 0.38 0.80 0.48

EFR Stress –SPS Method 0.48 0.43 0.60 0.44

EFR Stress –VMS Method 0.45 0.40 0.30 0.26

Unreliability-SPS Method 8.41 8.12 9.65 5.19




Outputs, Post-Processing, Automation

LoadAngle

FF

Cyclic Block Moment Diagram Oil Film Extent & Pressure Contours

Max. Acceptable End Load vs.Angle

Crankshaft Bending Animation




Summary

• GT-CRANK now meets all Cumminsrequirements for a fast crankshaft design

analysis tool• GT-CRANK now has a comprehensive crankshaft

durability analysis capability, while at the same

time it remains a rapid tool still offeringopportunities for optimization/DOE.

• Current GT-CRANK development work focused

on

• Dynamic solution CPU time improvement via harmonic (Herting)reduction

• Improvement of stress/fatigue scheme for split-pin crankshafts

cummins gt crank

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