vibration analysis of drivelines using mbd

Vibration analysis

of

Drivelines using MBD

Vib

ratio

n S

ym

po

siu

m. 3

0 M

ay 2

01

6, B

an

ga

lore

Manohar H C MBD Engineer

ProSIM R&D Pvt Ltd,

2

Mechanical systems

Crankcase

Chains/ Belts

Clutch

Gearbox

Propeller shafts

Differentials

Drive Shafts

Suspensions, etc.….

Introduction to MBD

Additional elemens

Rigid and Flexible bodies

Non-linear kinematic Joints

Moved reference systems

Closing loop constraints

Formulation in relative coordinates

Contact

Friction forces

Actuators and sensors

3

The basic concept of MBD is to create the equations of

motion for mechanical systems, and using various

calculation methods such as time integration to obtain a

solution for equation of motion.

Introduction to MBD

4

Introduction to MBD

So, Using MBD..

System Resonance analysis

Stochastic and transient response

Components level behavior assessment

Optimization

Stress and durability analysis

Hardware/software-in-the-loop

System simulation of any embedded designs

Cause of Vibration

Offsets in the joints

Unbalanced masses

Poor component design (Gear wheel, Constant joint, Drive shafts, Bearings)

Wrong selection of materials (Tires, Springs and Dampers)

etc.….

5

Introduction to MBD

Response Surface Modelling

FEA / Durability

CACE-Programs

CAD-Programs

Optimization

Real-Time Aerodynamics

MBD solver

6

Introduction to SIMPACK MBD

SIMPACK software is being developed by SIMPACK AG, Germany – Now acquired by Dassault

SIMPACK = General purpose Multi-Body Simulation (MBS) software

- General 3D MBS Model Set-up

- Powerful Time and Frequency Domain Solver

Accurate, Fast, Stable and Reliable

- 2D-Plot and 3D-Visualisation

- Optimised Application Specific Modeling Elements and

Analysis Methods

- Accurate Integration of Flexible Bodies

- Dynamic Load Data Export

7

Driveline modeling level

3-D driveline only

(Driveline Torsional Vibrations +

basic 3D driveline motion effects)

Complete system coupled 3-D driveline

(Driveline Torsional Vibrations +

Full system coupled 3D driveline motion effects)

1-D driveline only

(Driveline Torsional Vibrations only)

8

Principle Input data requirements of 1D driveline model:

- engine torque excitation look up table

(optionally gas pressure array --> will require additional crankshaft data)

- all 1D rotational moments of inertia

(shafts + tyre)

- all 1D rotational spring stiffnesses

(shafts, flywheel, elast. Couplings)

- all according 1D rotational damping values

- gearbox ratios + stiffness + damping

- tyre – rim rotational stiffness + damping

- principle 3D dimensions

Results to be achieved with 1D driveline model :

- rotational driveline mode shapes + natural frequencies

- all time histories of pure driveline torsional vibrations due to engine torque excitations


9

Principle data requirements of 3D driveline model:

- all 1D driveline input data

Additionally:

- 3D Mass properties of all 3D moved bodies

(mass, center of gravity, all inertia tensor values)

- detailed 3D hardpoint coordinates and

orientations of 3D driveline components

- 3D force element stiffness and damping

(engine mounts, subframe mounts, diff. gearbox mounts)

Results which can be achieved with 3D driveline model :

- all 1D driveline result data

Additionally:

- 3D driveline modeshapes + natural frequencies

- all time histories of all driveline torsional, translational and bending vibrations due to engine torque excitations and

3D pure driveline resonance/balancing effects


10

Principle data requirements of vehicle coupled 3D driveline model:

- all 3D driveline input data

Additionally:

- 3D Mass properties of all suspension system bodies !

(mass, center of gravity, all inertia tensor values)

- detailed 3D hardpoint coordinates and

orientations of suspension system !

- 3D force element stiffness and damping

of all suspension system force elements !

Results which can be achieved with

vehicle coupled 3D driveline model :

- all 3D driveline result data

Additionally:

- 3D mode shapes + natural frequencies of the coupled

complete vehicle system

- all time histories of all complete vehicle oscillations and vibrations of MBD

components due to engine torque excitations, 3D driveline resonance/balancing

effects, 3D vehicle resonance effects and road excitations


11

There are many driveline run-up related NVH effects

which can be analyzed and optimized using CAE methods,

•driveline torsional vibrations/resonances

•driveline (rigid body) beating effects

•driveline (flex. body) booming effects

•various driveline-chassis coupled resonance effects

•gear noise

•….

CAE based system design and optimization should be used in the development process in order to:

•improve system behavior

•reduce development time

•save development costs

Motivation of using 3D MBD analysis

12

Why using 3D MBD simulation for driveline run-up analysis ?:

Because 2D torsional dynamics analysis limited to only driveline torsional effects

Because 3D FEM analysis only covers linear effects and no time domain 3D coupled excitation/

dynamics effects in reasonable calculation time

3D MBD simulation approach covers:

• 3D driveline dynamics incl. flex bodies

• 3D chassis dynamics incl. flex. bodies

• coupled effects between chassis and driveline

• full range of 3D excitation mechanisms,

e.g.: - engine gas forces

- engine oscillating masses

- propeller shaft unbalance masses

- propeller shaft cardan joint excitation

•requirement to deliver results in reasonable calculation time

Motivation of using 3D MBD analysis

13

Principle MBD model setup: SIMPACK WIZARD:

- Configure and parameterize standardized MODELS

- Configure and parameterize standardized LOADCASES

- Create and run SCENARIOS (= MODEL + LOADCASE)

Model setup and scenario definition

14

Run Up Simulation definition:

Engine rotational and 3D shaking excitations due to

WOT fired engine including crank train masses:

--> engine gas force excitation

--> engine oscillating masses excitation

Internal 3D driveline excitations due to rotating 3D

driveline:

--> propeller shaft unbalanced excitation

--> propeller shaft cardan joint excitation

Run up characteristics via pre-defined roller test

bench velocity

--> absorbing engine torque

NVH Model setup and scenario definition

15

Selected analysis examples:

- 2D order analysis plots of torsional dynamics measurements

--> identify amount of torsional excitation and according torsional resonances

gearbox input torque

Propeller shaft front Propeller shaft center Propeller shaft rear

Result analysis methods

16


- 3D Campbell and 2D order analysis plots of chassis acceleration

measurements

--> identify chassis NVH relevant resonances


17


- Use MBD based chassis intersection forces and apply on an according FE model in order to calculate sound

pressure levels

--> estimate human NVH sensation


18

A 3D Multi Body Dynamics simulation based method in order to simulate the vehicle driveline run-up

NVH behavior was presented. Benefits of this approach are:

Identification of NVH relevant 3D driveline-chassis coupled run up resonances in early development stages

Getting detailed understanding of the according physical modes of action between chassis and driveline

Getting detailed understanding of the according vehicle parameter sensitivities

Easy and efficient way to identify and apply counter measures using DOE and optimization

According MBD models can be also used for many other chassis-driveline simulation scenarios (long. dynamics,

misuse scenarios, driveline loads, real time applications (ECU/TCU calibration)…)

Observation

19

Thank you !

For more information contact:

[email protected]

mailto:[email protected]




vibration analysis of drivelines using mbd

Engineering