Vibration analysis of Drivelines using MBD and the ability of the solvers is showcased in this ppt. Consideration of 1D, 2D and 3D MBD models for drivelines and performing order analysis for the same. Result shows the MBD capability of driveline simulations.

1. Vibration analysis
of
Drivelines using MBD
VibrationSymposium.30May2016,Bangalore
Manohar H C
MBD Engineer
ProSIM R&D Pvt Ltd,

2. 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. 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. 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.….

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Introduction to MBD
Response Surface Modelling
FEA / Durability
CACE-Programs
CAD-Programs
Optimization
Real-Time
Aerodynamics
MBD solver

6. 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

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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)

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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
Driveline modeling level

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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
Driveline modeling level

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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
Driveline modeling level

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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

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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

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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

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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

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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

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Selected analysis examples:
- 3D Campbell and 2D order analysis plots of chassis acceleration
measurements
--> identify chassis NVH relevant resonances
Result analysis methods

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Selected analysis examples:
- Use MBD based chassis intersection forces and apply on an according FE model in order to calculate sound
pressure levels
--> estimate human NVH sensation
Result analysis methods

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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

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Thank you !
For more information contact:
manohar.hc@pro-sim.com