impact of material behavior on engine development

Matej Smolnikar, Michael DeJack, Matej Strasek, Richard Tichy, Kazimierz Czubernat

AVL List GmbH (Headquarters)

Public

Impact of Material Behavior

on Engine DevelopmentInfluence of Porosity on Fatigue Life in Aluminum (part II)

DFE4902 - 4026 / - - 2.4 Matej Smolnikar, Michael DeJack, Matej Strasek, Richard Tichy, Kazimierz Czubernat | DAM | 08 April 2019 | 3Public

CAE GLOBAL HEADCOUNTStatus Q4/2008

Austria

USA

ChinaHungary

Germany

IndiaCroatia

Slovenia

France

US EU Asia Total

Design 42 431 47 520

Simulation 24 175 23 222

Mech. Dev. 10 132 30 172

Total 76 738 100 914

• More than 900 Engineers globally - near all customers

• Knowledge based innovative solutions

• Proven competence in production development projects

• Centralized development processes, tools, methods and quality system

Japan


Thermal Management

POWERTRAIN SIMULATION AREASSystem Simulation Engine Thermodynamics

Structural Mechanics

Electro-ComponentsEmissions / AftertreatmentNVH / Acoustics

Battery/Fuel cell Development


AVL FRONTLOADING PROCESS FOR “FIRST TIME RIGHT” PRODUCT DEVELOPMENT

Main challenges in all development processes:• Reduce development time

• Reduce cost• Increase reliability and durability


AVL FRONTLOADING PROCESS FOR “FIRST TIME RIGHT” PRODUCT DEVELOPMENT

Main challenges in all development processes:• Reduce development time

• Reduce cost• Increase reliability and durability

Goals:• Reduce number of hardware tests

• Increase number of virtual simulations using optimization tools and advance(d)

material modeling

Material quality validation and clarification


QUALITY LEVEL OF INPUT PARAMETERS

DESIGN ++

LOADS, CONSRAINTS, BOUNDARY CONDITIONS

+

*MATERIALS AND PRODUCTION PROCESS INFORMATION

-

RELEVANT INPUTS AND THEIR IMPORTANCE FOR QUALITY OF VIRTUAL SIMUALTION

Quality level of performed virtual simulations is highly dependent on quality of all input data required for virtual simulation Material properties are

seen as one of the key inputs for high quality FEA.

*Some required material data is missing and often available from customers. Material testing could

further improve quality and cost reductions for final product.


AVL APPROACH MATERIAL MANAGEMENTFOR HIGH QUALITY FEA

Centrally managed material data base for all CAE tasks

Consistent constitutive material cards for stress/strain HCF and crash/crush damage modelling

Consistent TMF and damage models merged in AVL XMAT TMF Pre/Postprocessing tool

Base data sets validated and updated according to component specific measured data

Material testing definition and supervision of material testing

Benchmarking of material properties and material classes

3-4 full time material experts for CAE data processing and material/damage modelling

*Material status January 2019

FKM Guideline and

AVL know how

AVL XMAT TMF Pre/Postprocessing tool

Crash/crush damage modeling

Commercially available


BACKGROUND OF MATERIAL PROPERTIES PREDICTION FROM FKM GUIDELINE

ATC [M

Pa]

Rm [MPa]

ZK AlSi8 Sr T5

ZK AlSi7 Sr T6

ZK AlSi7 Sr T7

FKM

Using general approach from FKM guideline results typically in over- or under-estimation

of fatigue life

local material information is required in order to improve

lifetime prediction.

ATC

[MPa]

deq

ZK AlSi8 Sr T5

ZK AlSi7 Sr T6

ZK AlSi7 Sr T7

ATC

[MPa]

Log() √area

ZK AlSi8 Sr T5

ZK AlSi7 Sr T6

ZK AlSi7 Sr T7

TS-Z

F (

range o

f dis

p)

DAS [microm]

ZK AlSi8 Sr T5

ZK AlSi7 Sr T6

ZK AlSi7 Sr T7

ATC – alternating tension compression fatigue lifeTS-ZF – range of dispersionFrac MW deeq – mean equivalent max. pore diameterFrac MW w_A – mean square root surface of projected maximum poreDAS – dendrite arm space

El-Haddad

Significant influences on fatigue properties coming from variation

in local cooling conditions and porosity (defect size)

Murakami


AVLComponent FEA simulation

Cylinder head FEA simulation

COMET PROJECT: POROSITY INFLUENCE ON FATIGUE LIFE IN CASTED ALUMINUM

*Comet project (2014-2017)

NemakCylinder head,

crankcase casting

MCLX-ray

CT Analysis

AMB Specimen and

component testing

Damage modeling

MAGMACasting Simulation

Microstructure features & pore size

ABAQUS/FEMFAT/

Murakami, El-Haddad

Projekt Nr.: Maschine:MOT 100 kNR: -1,0

A1.20 Datum: 03/17 a [mm]: -

Leitner Versuchsart: l [mm]:

Durchführer: Garb ZD dS [mm]:

Material: Oberfläche: Wärmebehandlung: TS - ZF: 1: 2,09

AlSi8Cu3 geschliffen T5 TS - DF: 1: 1,26

Proben Nr. F [N] Sa [N/mm²]

erreichte

Schwingspiel

zahl

d

[mm]

45NW2 8127 55 4.004.650 18,8x18,76

45NW4 7389 50 1.500.690 18,8x18,65

35NW3 7388 50 8.543.380 18,7x18

35NW2 8127 55 6.868.250 18,7x18

54NW3 8866 60 723.214 18,8x18

54NW1 7388 50 1.633.360 18,7x18

34NW3 6649 45 2.000.550 18,75x18

34NW1 6649 45 10.000.000 18,6x18

34NW1 13299 90 356.676 18,6x18

34NW2 6649 45 10.000.000 18,6x18

34NW2 13299 90 738.416 18,6x18

54NW2 8866 60 708.233 18,8x18

35NW1 8127 55 2.174.111 18,7x18

Bemerkungen

gestoppt, wiedereingesetzt

gestoppt, wiedereingesetzt

Bez.:

Leiter:

Probenform:

bauteilnah


COMET PROJECT OBJECTIVES

Objectives Prediction of local microstructure, particularly pore size distribution, from casting simulation Development of a multi-effect material model to predict fatigue behavior based on microstructure Linking casting simulation and fatigue design with respect to local material behavior

The project is structured in 6 interacting Work Packages (WPs).WP1: Prediction of characteristic microstructural features

Casting simulation using Magmasoft. The results will be the local pore size distributions throughout the entirecomponents investigated as well as a model for pore size prediction.

WP2: Influence of local cooling conditions on fatigueCrucial microstructural parameters influencing fatigue behavior and the characterization of their quantitativeinfluence on fatigue strength.

WP3: Influence of eutectic morphology on fatigue behaviorCharacterize the influence of Si-morphology modified by Na vs. Sr on fatigue behavior and to identify themicrostructural causes for different fatigue behavior.

WP4: Influence of heat treatment on fatigue behaviorComparison of a heat treatment procedure yielding maximum strength with a heat treatment procedure yieldingmaximum elongation at fracture when tested under fatigue loading conditions.

WP5: Influence of elevated temperatures on fatigueIdentification of the crucial microstructural parameters influencing the fatigue behavior at elevated temperatures.

WP6: Material model development and validationIncorporation of the developed fatigue design models from WP1 to 3 into a fatigue design routine accounting forlocal microstructure based on casting simulation and its validation.


VARIATION OF LOCAL MATERIAL PROPERTIES IN CYLINDER HEAD MAPPED FROM MAGMA

*ATC = Alternating tension compression (R-1), Material data summary from AlSi7Cu0.5Mg-T6W

Significantly different ratio of fatigue data (up to a factor of 3) compared to static material data is depicted (up to 1.3)

Local material properties have significant impact on design and lifetime assessment.

Min. Max. Min. Max. Min. Max. Min. Max.

Cylinder Head 1.0 3.1 1.0 6.1 1.0 1.3 1.0 1.2

Firedeck 2.2 3.0 1.1 2.4 1.2 1.3 1.1 1.2

Gas port intake 1.0 3.1 1.3 5.4 1.0 1.3 1.0 1.1

Gas port exhaust 1.3 3.1 1.4 5.5 1.0 1.3 1.0 1.1

Water jacket 1.0 3.1 1.1 5.5 1.0 1.3 1.0 1.2

Oil 1.0 3.1 1.4 6.1 1.0 1.3 1.0 1.1

NW 1.0 3.0 1.2 6.1 1.0 1.3 1.0 1.2

AlSi7Cu05Mg-T6W

Rp02RmDASATC*Normalized variation of

material properties


FEA APPROACH:STANDARD / ADVANCED PROCESS

Fatigue tests Alternating tension compression (50%SP@1E7Nf)

Test data FEA Material

STANDARD PROCESS ADVANCED PROCESS

DAS, U

TS,

ATC

Homogeneous material propertiesMaterial static and fatigue

Properties are locally dependent.


HAIGH DIAGRAM AND S/N CURVES

Important for FEA:• difference in slope of SN curve,• difference in knee point of SN curve• variation of fatigue and static data; in head fire deck (BR)

typically better quality compared to cam shaft region (NW) is depicted.

BR – specimens tested from cylinder head fire deckNW - specimens tested from cylinder head cam shaft (top deck)


LOCAL MATERIAL PROPERTIES MAPPED FROM MAGMA COMPARED TO MEASURED DATA

Comparison between measured and mapped local material properties shows good correlation at cylinder head fire deck (BRR) as well as at cam shaft region (NW).


MICROSTRUCTURAL EFFECTS: LOCAL MATERIAL PROPERTIES IN FEMFAT

Slope of S/N curve, Cycle limit o Endurance and Range of Dispersion were estimated from UTS.

Parameters derived from MAGMA; Murakami and ElHaddad damage approach


VERIFICATION OF FEA PROCESSABAQUS MODEL SETUP

Tension/compression loading (R-1) of „component” extracted from cylinder head cam shaft region.

Tension

Compression

F=13.3 kN (def x100)

Variation of stress through thickness

(not symmetric part)


COMPARISON BETWEEN MURAKAMI APPROACH WITH AND WITHOUT RESIDUAL STRESSES

• Murakami approach with residual stresses shows better correlation with component test than Murakami approach without them.

●Orange – Nockenwelle, with residual stresses, Murakami approach●Gray – Nockenwelle, without residual stresses, Murakami approach

w

C1, C2, m2: Parameters of fatigue approach by MurakamiHV: Vicker HardnessArea : projected area of microporew: alternating tension compression fatigue life at 1E7 Nf


𝑆𝑎 =∆𝐾𝑡ℎ

𝑌 ∙ 𝜋 ∙ 𝑎 + 𝑎0

COMPARISON BETWEEN ELHADDAD APPROACH WITH AND WITHOUT RESIDUAL STRESSES

• Wohler curves for ElHaddad approach with and without residual stresses are within scatter of material test data.

• NW and BRR material models shows comparable results for ElHaddad approach.

●Light blue – Nockenwelle, with residual stresses, ElHaddad approach ●Lime – Nockenwelle, without residual stresses, ElHaddad approach ●Dark blue – Brennraum, with residual stresses, ElHaddad approach

A, ao = material constantDKth = crack propagation thresholdY = geometry factorSa: alternating tension compression fatigue life at 1E7 Nf


COMPARISON BETWEEN MURAKAMI AND ELHADDAD APPROACH

●Orange – Nockenwelle, with residual stresses, Murakami approach●Light blue – Nockenwelle, with residual stresses, ElHaddad approach 28.01.2019●Yellow – Nockenwelle, with residual stress, without local material properties

• Murakami and ElHaddadapproaches lie inside the component test scatter. Wohler curve for ElHaddad approach shows conservative results.

• Wohler curve without local material properties (using fire deck material data) results in rather optimistic life time and is outside the component test zone.


N1148750SF=1.00

N1150112SF=1.00

N1148750SF=0.93

N1150112SF=0.93

EXAMPLE:CYLINDER HEAD

1. STEP: Assembly_Min2. STEP: Assembly_Max3. STEP: Warm_Engine4. STEP: Fix_Bolts5. STEP: GL-16. STEP: GL-27. STEP: GL-38. STEP: GL-49. STEP: No_Loads

HCF assessment: Constant material properties

HCF assessment: Local material properties sameROD

* same Parameters of FEMFAT settings are used

Current simulations show decrease of fatigue life time using local material properties in most critical location of used cylinder head.• Fatigue data derived from fire deck location seems to be optimistic with

respect to rest structure• Used range of dispersion (ROD) of 1.4 combined with local material

properties seems to be high include ROD as input data for safety factor assessment.


N1148750SF=0.93

N1150112SF=0.93

EXAMPLE:CYLINDER HEAD

HCF assessment 3:Local material properties, with slope of S/N curve,

local ROD, ElHaddad

HCF assessment 2:Local material properties, ROD=1.4,

ElHaddad

N1148750SF=1.00

N1150112SF=1.00

N1148750SF=1.00

N1150112SF=1.29

HCF assessment 1: Constant material properties, ROD = 1,4 from

NW

Safety factor results are normalized.

• Significant effect on fatigue life using local material parameters is depicted.

• Detail investigation of influence parameters is to be performed in order to define reliable local material range of dispersion (ROD) for series production in case local material data are used.


SUMMARY

• Material tests confirm non-homogeneous material properties over cylinder head and significant difference in fatigue strength (fire deck, mid deck and camshaft region).

• Data transfer between Magma and FEMFAT was performed.

• Lifetime assessment approach was validated using different base and local material properties for lifetime assessment.

• Effect of residual stresses can have a decisive role on life time prediction.

• Different damage models (Murakami, El-Haddad) lead to different fatigue strength levels related to critical defect sizes.

• Further material testing program using higher number of samples from different component regions in order to define local material scatter (range of dispersion) for series production is recommended.

• Combining test results with casting simulation could further improve quality of FEA life time prediction. Results might have significant role in case of weight optimization.


REFERENCES

• COMET Projekt AMB, Nemak, MCL, Magma, AVL; Integration of casting simulation into computational fatigue design of aluminum castings (Comet; A1.20), 2014-2017

• C. Garb: Materialmodellentwicklung für die betriebsfeste Auslegung von Aluminiumgussbauteilen, Dissertation, AMB 2017

• C. Garb, M. Leitner, B. Stauder, D. Schnubel, F. Grün: Application of modified Kitagawa-Takahashi diagram for fatigue strength assessment of cast Al-Si-Cu alloys, International Journal of Fatigue 111 (2018) 256-268.

• C. Garb, M. Leitner, F. Grün: Application of √area-concept to assess fatigue strength of AlSi7Cu0.5Mg casted components, Engineering Fracture Mechanics 185 (2017) 61-71.

• C. Garb, M. Leitner, F. Grün: Effect of elevated temperature on the fatigue strength of casted AlSi8Cu3 aluminium alloys, Structural Integrity Procedia 7 (2017) 497-504.

• M. Leitner, C. Garb, H. Remes, M. Stoschka: Microporosity and statistical size effect on the fatigue strength of cast aluminium alloys EN AC-45500 and 46200, Materials Science & Engineering A 707 (2017) 567-575.

• M. Weidt, R. A. Hardin, C. Garb, J. Rosc, R. Brunner & C. Beckermann: Prediction of porosity characteristics of aluminium castings based on X-ray CT measurements, International Journal of Cast Metals Research 31, 289 (2018).

• C. Garb, M. Leitner, M. Tauscher, M. Weidt, and R. Brunner: Statistical analysis of micropore size distributions in Al–Si castings evaluated by X-ray computed tomography, International Journal of MATERIALS RESEARCH, 109, 10 (2018).


REFERENCES

• M. DeJack, M. Smolnikar, R. Tichy: Impact of material behavior on engine development: Influence of porosity on fatigue life in aluminum, FEMFAT User meeting USA, 2018

• M. Weidt, C. Thomser: Methodische Integration der virtuellen gießtechnischen Optimierung in die Bauteilentwicklung zur betriebsfesten und robusten Auslegung von hochbelastetenAluminiumgussteile, 10. VDI-Fachtagung „Gießtechnik im Motorenbau 2019“ Magdeburg, 2019

impact of material behavior on engine development

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