PragTic in ApplicationPragTic in Application

Fatigue in Riveted Fatigue in Riveted JointsJoints

The organisation of the meeting is partially financed from OPPI programmeCzech Technology Airspace Platform, reg. number SPTP 01/004

Jan PapugaJan Papuga

Evektor, spol. s r.o.Evektor, spol. s r.o.Founded in 1991Founded in 1991

Design activities Design activities from 1992from 1992

Fully private owned Fully private owned companycompany

Scope of ProjectsScope of ProjectsDesign studioDesign of components Design of jigs, fixturesStress analysis

Interiors designFE-analysis including crashes

Stamping tools

Plastic parts

Preliminary designof mechanisms

Complete development

Prototypetooling

Aircraft structuresAircraft structuresVUT 100 EV-55

IMPERJA ProjectIMPERJA Project• ImpImproving the Fatigue Performance of roving the Fatigue Performance of RRiveted iveted JJoints in oints in

AAirframesirframes

• EUREKA programme of EUEUREKA programme of EU

• International project with partners mainly from PolandInternational project with partners mainly from Poland

Institute of Aviation, Warszawa, PolandInstitute of Aviation, Warszawa, Poland - coordinator - coordinator

AGH University of Science and Technology, Krakow, PolandAGH University of Science and Technology, Krakow, Poland

ATR University of Technology and Agriculture in BydgoszczATR University of Technology and Agriculture in Bydgoszcz, ,

PolandPoland

WAT Military University of TechnologyWAT Military University of Technology, Warszawa, Poland, Warszawa, Poland

PZL Mielec, Mielec, PolandPZL Mielec, Mielec, Poland

Stresstech Oy, Vaajakoski, FinlandStresstech Oy, Vaajakoski, Finland

Evektor ParticipationEvektor Participation

• WP12: Experimental analysis of WP12: Experimental analysis of

riveted specimensriveted specimens

• WP13: FEM-based analysis of WP13: FEM-based analysis of

riveted specimensriveted specimens

• WP14: Fatigue analysis of riveted WP14: Fatigue analysis of riveted

specimens based on WP13 resultsspecimens based on WP13 results

ExperimentsExperimentsEVE1

R=0.14 results at four load levels

EVE2R=04 results at four load levels

EVE1 su [MPa] N [-]

LR1 160.7 3 631LR2 108.475 16 093LR3 64.675 134 453LR4 37.575 733 014

EVE2 su [MPa] N [-]

LR1 190 11 808LR2 140 57 003LR3 100 573 116LR4 80 1 857 551

FEA AnalysesFEA AnalysesProblems above all with EVE1

very thin cylindrical part below the countersunk headpronounced changes of elements shape at this regionremeshing would be suitable

FEA Analyses IIFEA Analyses II

Shear tests:

EVE1

EVE2

EVE1

Inputs for Fatigue Inputs for Fatigue AnalysisAnalysis

• FEA ModelFEA Model

– built in MSC.Patran => *.nas file existsbuilt in MSC.Patran => *.nas file exists

– outputs from MSC.Marcoutputs from MSC.Marc

• can be read back to Patrancan be read back to Patran

• local stress and strain tensors at various load incrementslocal stress and strain tensors at various load increments

• Experimental dataExperimental data

– final lifetimes (just for comparison with fatigue final lifetimes (just for comparison with fatigue

prediction)prediction)

– material properties – derived from available material properties – derived from available

referenced datareferenced data

– load dataload data

PragTic in Application IPragTic in Application IFirst RunFirst Run

• Registration to http://www.pragtic.comRegistration to http://www.pragtic.com

• DownloadDownload

• Unzip to desired location – example C:\Test\Unzip to desired location – example C:\Test\PragTic\PragTic\

• Edit of WinPragTic.ini file – renaming the Edit of WinPragTic.ini file – renaming the paths:paths:DIR C:\Test\PragTic\HOME C:\Test\PragTic\IMAGES C:\Test\PragTic\MPORT C:\Test\PragTic\XPORT C:\Test\PragTic\MDB C:\Test\PragTic\PragTic_MDb.matERROR 1e-10EM_BUFF 100000

• Run of the executableRun of the executable

PragTic in Application II PragTic in Application II Import of FE-Model TopologyImport of FE-Model Topology

• Import of *.nas fileImport of *.nas file

• Let the normals to be calculatedLet the normals to be calculated

– It does not take so longIt does not take so long

– It is useful for detection of surfaces of indivindual partsIt is useful for detection of surfaces of indivindual parts

PragTic in Application IPragTic in Application IIII I

Import of Result Files – Make MapImport of Result Files – Make Map• Preparation of map file for FEA results Preparation of map file for FEA results

importimport

HereHere

PragTic in Application PragTic in Application IIIIIIbisbis

• General input of FE-data in formatted General input of FE-data in formatted

recordsrecords

See See Help Help for for PragTiPragTicc

PragTic in Application PragTic in Application IV IV

Import of Result Files – Command LineImport of Result Files – Command Line• Input of further Input of further

result files from result files from

the the command command

lineline

PragTic in Application PragTic in Application V V Decrease of the Task SizeDecrease of the Task Size

• Only critical localities should be evaluatedOnly critical localities should be evaluated

• PragTic is not a commercial SWPragTic is not a commercial SW

• You are the one who has to optimize the You are the one who has to optimize the

computation timecomputation time

– Focus on surface nodes (N_NRM node set)Focus on surface nodes (N_NRM node set)

– Check the nodes with highest loading (Tools-Check the nodes with highest loading (Tools-

>Results->Tensors – you can get Mises stress, >Results->Tensors – you can get Mises stress,

principal stresses…)principal stresses…)

– Select nodes around expected notches (Filter Select nodes around expected notches (Filter

tool)tool)

PragTic in Application PragTic in Application VVII

Coordinate SystemsCoordinate Systems• Use of other coordinate systems can be handyUse of other coordinate systems can be handy• Nodes, result files can be viewed in various Nodes, result files can be viewed in various

c.s.c.s.• C.S. can be defined within PragTicC.S. can be defined within PragTic

– cartesian, cylindrical, sphericalcartesian, cylindrical, spherical– C.S. can be defined in other C.S. than the global C.S. can be defined in other C.S. than the global

oneone

• Definition of coordinate systems of holesDefinition of coordinate systems of holes– two two vectorsvectors and the origin have to be input and the origin have to be input– leading axisleading axis

• the only vector, which represents the real axis of the new the only vector, which represents the real axis of the new coordinate systemcoordinate system

• the other vector serves just for a definition of the plane to the other vector serves just for a definition of the plane to which the third axis is found as perpendicularwhich the third axis is found as perpendicular

PragTic in Application PragTic in Application

VVIIII Filter ToolFilter Tool – Selection by Property – Selection by Property

• The nodes with The nodes with maximum distance maximum distance 3 mm from the 3 mm from the hole No.1 center hole No.1 center will be selectedwill be selected

PragTic in Application PragTic in Application

VVIIIII I Filter ToolFilter Tool – Selection by Set – Selection by Set

• Nodes from Nodes from the area of the area of interest interest (N_HOLE), (N_HOLE), but lying on but lying on the surface of the surface of components components only (N_NRM only (N_NRM set), will be set), will be selectedselected

PragTic in Application PragTic in Application IX IX

Results – Averaging to Nodes (ERATON)Results – Averaging to Nodes (ERATON)• Results read into PragTic as printed out at nodes of Results read into PragTic as printed out at nodes of elements, have to be averaged to nodeselements, have to be averaged to nodes

• Decrease of the task sizeDecrease of the task size

PragTic in Application PragTic in Application X X Results – SuperpositionResults – Superposition

• Tools-Tools->Arrays->Superpose>Arrays->Superpose– two data_vectors of similar two data_vectors of similar

length but different weight length but different weight coefficient, can be superposedcoefficient, can be superposed

• Another adept for Another adept for command linecommand line

PragTic in Application PragTic in Application XXII

Load Regime DefinitionLoad Regime Definition

• The local load history can be defined on The local load history can be defined on basis ofbasis of

– FEA result files at FEA result files at different load leveldifferent load level

Elastic solution Elastic-plastic solution

– FEA result filesFEA result files– coefficients to get them coefficients to get them

to adequate load levelto adequate load level– load historiesload histories

• Load Regime is a Load Regime is a compound ofcompound of

Elastic solution

– mathematical formulamathematical formula– load sequenceload sequence

Elastic-plastic solution

– result file sequenceresult file sequence– transient local load transient local load

historyhistory

PragTic in Application PragTic in Application

XXIbisIbis Load Regime Definition – Transient Load Regime Definition – Transient

Load HistoryLoad History• Its preparation is a necessary condition to run the Its preparation is a necessary condition to run the analysisanalysis

• LR definition as a result file sequence cannot be LR definition as a result file sequence cannot be used in fatigue analysis yetused in fatigue analysis yet

PragTic in Application PragTic in Application

XXIIII Material DefinitionMaterial Definition

1.1.Import from an Import from an older analysisolder analysis

2.2.Direct creationDirect creation

3.3.Using data from Using data from the material the material databasedatabase

PragTic in Application PragTic in Application

XXIIIIIICalculation Methods Selection and Calculation Methods Selection and

SetupSetup• Default Default

values values proposedproposed

• Check Check existence existence of all of all necessary necessary material material datadata

PragTic in Application PragTic in Application

XXIVIVCalculation Run (Analysis Setup)Calculation Run (Analysis Setup)

• The The Analysis Analysis Setup Setup can be can be savedsaved

PragTic in Application PragTic in Application

XXVVFatigue Results ViewingFatigue Results Viewing

• AllAll fatigue results can be viewed or exported fatigue results can be viewed or exported

PragTic in Application PragTic in Application

XXVIVIFatigue Results ExportFatigue Results Export• Two options currentlyTwo options currently

• FEMAP (*.neu file)FEMAP (*.neu file)• Ansys (input file)Ansys (input file)

LandgrafEVE1LR1(maximum load)

SWT

SocieLESA

PragTic in Application PragTic in Application

XXVIbisVIbisFatigue Results Fatigue Results

EVE1, SWT

LR1 (max) LR2

LR4LR3