Automotive Noise and Vibration Congress 2016

25/01/16 www.pro-sim.com

Design & Development of an Integrated Transmission System

A case study of successful collaborative engineering between

AVTEC & ProSIM R&D Pvt Ltd

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PREAMBLE

Issues involved in development of a Integrated transmission system for AWD

Optimizing the product (material, geometry for needed performance)

Success of collaborative engineering for product innovation and NPD

Optimizing the investments and optimization of RoI are discussed.

ProSIM

- A simulation technology based collaborative R&D company

- Inter disciplinary team of experts

- Design –materials - Manufacturing-performance

- Multi-physics simulation capabilities


ProSIM

- We assist customers in

- New product development

- Innovation / R&D projects

- VA / VE

- Failure analysis


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Design of Gearbox

Product design and development

An integrated transmission for vehicle having 5 forward speeds & 1 reverse speedwithin the specified torque & rpm range.

4th Gear3rd Gear

2nd Gear1st Gear

Reverse Gear

5th Gear Front Output

Rear Output

Workflow- Study the customer requirements

- Design specifications and conceptualisation

- Engineering design

- Digital mock up

- CAE and FEM analysis

- Durability analysis

- MBD model (flexible model)

- NVH Analysis

- Optimisation

- Physical prototype

- Testing

- Design fine tune

- Control drawing release


Design Validation of an Integrated Transmission

System

Automotive Noise & Vibration Congress, Pune

• Introduction

____________________________________________________

• Integrated Transmission & Transfer Case

• Features

____________________________________________________

• Conceptualizing the Product

• Mass addition for Shift-ability

• Testing on Acoustic Chamber

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Introduction 7-Feb-16

OEM’s demands higher performance, NVH, safety & quality are increasing

day by day.

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7-Feb-16

It is now necessary to utilize company’s investment in design stage gate

process qualification, virtual prototyping & physical prototyping.

Development of superior design is mandatory as technology, methods,

guidelines & tools are available on finger tips.

Design is signed off for performance, quality, safety & cost so that a

higher upgraded version of the model can be achieved after passing all the

stage gates.

Business Case FeasibilitySchematic

DesignDesign

DevelopmentPre

ConstructionConstruction

Introduction

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Integrated Transmission & Transfer Case7-Feb-16

5 speed manual transmission Motor shift transfer case

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Cut section 7-Feb-16

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7-Feb-16

HIGH GEAR PAIRGEAR RATIO: 1.205

LOW GEAR PAIRGEAR RATIO: 2.127

4TH GEAR PAIRGEAR RATIO: 1.000

3RD GEAR PAIRGEAR RATIO: 1.3642

2ND GEAR PAIRGEAR RATIO: 2.260

1ST GEAR PAIRGEAR RATIO: 3.737

REVERSE GEAR PAIRGEAR RATIO: 3.4028

5TH GEAR PAIRGEAR RATIO:

0.7757

TRANSMISSION

TRANSFER CASE

Gear Train

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Features 7-Feb-16

This transmission is designed for a vehicle which is on-road luxurious SUV

& at the same time can run on ice covered roads too.

Demands speed & torque at different times.

The unique feature is that transfer case is directly mounted on rear cover of

transmission for compactness.

It compliment design of engine, axle, propeller shaft & tunnel of vehicle

very well.

All the designed parts were gone through design stages such as

DFMEA/PFMEA.

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7-Feb-16

All the parts of the transmission are built to sustain a temperature range of

-30 degree Celsius to 50 degree Celsius.

Material selection for all parts is done for adverse condition and considering

variations in temperature.

The B10 life for all the parts qualifies as per demanded.

Effect of all torque transfer parts such as gear, shafts, synchronizers,

bearings were analysed with respect to the manufacturing accuracies.

All the design were checked for serviceability, assembly, quality & cost

before signing off with customer.

Features continues…

Conceptualizing the Product

2/7/2016

Initial Study & Data Receipt

13.69° (~14 °)

Shift-ability

Shifting Testing 2/7/2016

07/02/2016

S.no. % of total time Front Axle (% of total torque) Rear Axle (% of total torque)

1 10% 100% 100%

2 30% 120% 80%

3 30% 80% 120%

4 10% 140% 60%

5 10% 60% 140%

6 5% 200% 0%

7 5% 0% 200%

Load Cases for testing

Modelling and Simulation

- ABAQUS is used for finite element analysis

- FESAFE is used for fatigue damage and durability assessment

- SIMPACK is used for flexible multi-body dynamic simulation (order analysis, NVH, etc)


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Modeling and Simulation

Multi-body dynamic Simulation

Components in the main model -Flexible housing

-Flexible shafts

-Gear wheels

-Synchronizer

Components:Flexible bodies Figure: Flexible Body generation in SIMPACK – Steps followed

Drive train modeling

Components:Gear

1. Normal Module

2. Normal Pressure Angle

3. Helix Angle

4. Number of Teeth

5. Addendum Diameter\Height\Coefficient

6.Deddendum Diameter\Height\Coefficient

7. Shift Factor

8. Flank Width


Calculation accordance with DIN 3990-1:1987-12

Gear pair Parameters Analytical calculation


BearingsBall bearings

Needle roller bearings

Nonlinear bearing stiffness value


Speed engagementLoad case

Figure: Example load case as 1st gear engaged

Input torque

Reverse torque


Drive train Main model

Topology

Topology diagrams ease the understandability of the model

FE43 - Force Element Representing BoltingFE225 - Force element representing gear pairDOF - Degrees of FreedomFE93 - Force Element Representing input torque

MBD Result

Using MBD Bearing forces

The Bearing reaction forces are considered as an input for

Structural analysis of housing components as shown in

the figure.

By FFT (Fast Fourier Transform) converted bearing loads

it could be possible to conduct housing acoustic analysis

in FE.

Figure: Bearing reaction forces

Vibration analysis of gearbox

Methodology and Inputs

• Flexible gear shafts

• Switchable gears

• Bearings (Non linear stiffness and damping values)

• Synchro bodies as dummy bodies

• Rigid gearwheels with detailed macro- and micro-geometry

• Gearwheels with material data

• Gear pair contact

Figure: Nonlinear bearing stiffness valueFigure: Gear tooth modification

Vibration analysis of gearboxSensors at Probe location

on housing to extract accelerations

Figure shows the sensors location on the

housing components

The resultant housing acceleration in all

direction captured at sensors locations.

Probe locations

MBD Result Vibration analysis of gearboxRMS velocity at probe - 2

MBD Result Vibration analysis of gearboxAcceleration at probe - 2

MBD Result Vibration analysis of gearboxCampbell plot for acceleration at probe - 2 Housing Acceleration

From the figure shows critical RPM for a particular order(3rd Gear pair and 2nd harmonic of

TC Gear pair) of vibration indicating the source of high vibration in the system

Observation

Vibration analysis of gearbox

1. In order analysis the RPM is increased from 0 to maximum, with a constant

acceleration. This is done in order to see at what RPM the system has maximum

amplitude of vibration

2. The maximum amplitude of vibration occurs because of the interaction of natural

frequencies of vibration and forcing frequencies (teeth meshing frequency of any one

of the gear pairs).

3. The natural frequencies also considerably depends on the mounting locations of the

housing. The critical RPM may change if the mounting locations and stiffness values

are varied

Assembly

Description of the transmission assembly

Description of the differential gear system

Boundary condition

The transmission assembly is fixed in bearing locations (highlighted - six location), Theshafts are allowed to rotate along the shaft axis (rotation along X– direction).

Results – Transmission Assembly

Results – Transmission Assembly

Results – Differential gear Assembly

Durability

Fatigue analysis is carried out taking the results of non linear static FE results.

Appropriate fatigue material properties are assigned for all the components from the

material library of the software and a cyclic half sine wave load (zero to max) is

applied to predict the fatigue life of the system.

Fatigue life of Transmission assembly

Minimum Fatigue life (crack initiation life) observed in the Transfer case assembly is as shown.

Fatigue life of transfer case

NVH

The air meshing is considered as a cylinder of 350 mm radius from the Transmission axis

Noise Probing location

Noise predicted in simulation

Noise Comparison at probe location-8

Conclusions- A integrated transmission system for SUV with AWD is

developed- Static Stress, modal/ harmonic analysis, contact stress

analysis carried out using ABAQUS.- Customer desired fatigue life and noise levels have been

achieved by simulation based studies (using Abaqus, Fesafeand SIMPACK)

- Physical testing & prototyping time &effort is reduced.- Using good collaborative practices between ProSIM and

AVTEC, a new transmission system was developed in a short time, with minimal cost.
