CAE analysis of a conrod for motorbike application · Inertia relief on. ANSYS Conference & 26th...

ANSYS Conference & 26th CADFEM Users´ Meeting

CAE analysis of a conrod for motorbike application

R. Testi ([email protected])Piaggio & C. SpA – Italy (www.piaggio.com)


Presentation outline

• Company profile• Object of the study• Analysis methodology• Results• Synopsis


Company profile – Piaggio Group

Business areas

2-wheelers

Light Transport Vehicles

Light Transport Vehicles

Engines

Spare parts and accessoriesSpare parts

and accessories



Brands managed



A few figures

• one of the world’s top four manufacturers of two-wheel motor vehicles

• consolidated leadership position on the European 2-wheeler market

• approximately 7,000 employees• facilities: Pontedera (Pisa-Italy); Scorzè (Venice-Italy); Mandello del Lario (Lecco-Italy); Barcelona (Spain); Baramati (India)

• R&D centres: Italy, Spain, China and India• vehicle sold in 2007: 708,500• net sales in 2007: 1,692 million Euro


Object of the study

Aprilia ShiverAprilia ShiverNew 1200 cctwin engine

New 1200 cctwin engine

ConrodConrod

Prediction of fatigue performance

Prediction of fatigue performance

Max power �� 103 kWMax torque �� 120 Nm


Analysis methodology

CAD software

Geometry ANSYS/Workbench

Dynamic Load/stress transfer functions

MBS software

Durability softwareLoad time-histories

Safety factor

Static stresses

Inertia propertie

s


ANSYS/Workbench analyses

NonlinearNonlinear LinearLinear

ANSYS/Workbench


Static stresses


ANSYS/Workbench nonlinear static analysis

Frictional contacts with interferenceFrictional contacts with interference Bolt pretensionsBolt pretensions




ANSYS/Workbench


Static stresses


ANSYS/Workbench linear static analysis (1/2)

Unit loads at conrod’s interfacesUnit loads at conrod’s interfaces

Cylindrical jointsCylindrical joints

Unit magnitude bearing loadsUnit magnitude bearing loads


ANSYS/Workbench linear static analysis (2/2)

Stepped Static Structural analysis

RST file’s structure

Loadstep Content

1 Bearing load #1

2 Bearing load #2

… …

Ready to be coupled with load time-histories

One load per step

Inertia relief on



CAD software



MBS software


• Stress tensor • Safety factor

Static stresses

Inertia propertie

s




Requirement for durability analysisRequirement for durability analysis

Same node/element numberingSame node/element numbering

ANSYS/Workbench


Static stresses


ANSYS/Workbench analyses – dummies to keep same numbering

Workbench

NonlinearNonlinear

LinearLinear

Dummies to keep the

PRETS179s

Dummies to keep the

PRETS179s

Dummies to keep the SURF154s

Dummies to keep the SURF154s



CAD software



MBS software



Static stresses

Inertia propertie

s


MBS analysis (1/2)

Bench test conditions Testrig rotary inertia

Gearbox

Gas forces


MBS analysis (2/2)

Gas forces

— Conrod #1 --Conrod #2

Longitudinal forces on conrod #2

— Big eye --Small eye

Combined with load/stress TF by

durability SW

Combined with load/stress TF by

durability SW



CAD software



MBS software



Static stresses

Inertia propertie

s


MBS

Durability analysis (1/2)

Workbench

Load/stress transfer functions

Load time-history

X = Stress tensor time-history

Dummy unit time-histories for static loads


Durability analysis (2/2)Model structure

FEM results

MBS results

Linear combinations

Solver parameters


Results (1/3)Safety factor vs. endurance limit

Minimum allowable value according to Piaggio standards

1.25

SOUND CONROD DESIGN


Results (2/3)

Most damaging load

Omitting given load channel


Results (3/3)

Most severe condition

TDC – start of power stroke


Synopsis

New engineNew engine

CAE assessment of

critical components (crankshaft, crankcase, conrod, ...)

CAE assessment of

critical components (crankshaft, crankcase, conrod, ...)

Combined use of different

tools

Combined use of different

tools

Central role of ANSYS/Workbench

Central role of ANSYS/Workbench

Load/stress TF computation

Load/stress TF computation

� Both linear and nonlinear models� Inertia relief� Compatiblity with other SW by

dummy outline branches

� Both linear and nonlinear models� Inertia relief� Compatiblity with other SW by

dummy outline branches

Design soundness proved by ensuing durability analysisDesign soundness proved by ensuing durability analysis

Thank you for your patience!

CAE analysis of a conrod for motorbike application · Inertia relief on. ANSYS Conference & 26th...

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