Noise and Vibrations for automotive-umashankar

3DS.COM©DassaultSystèmes|ConfidentialInformation|6/5/2016|ref.:3DS_Document_2015
Noise & Vibrations (N&V) for
Automotive System
Umashankar G
Center for Simulation Excellence (CSE)

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Automotive N&V
N&V Simulation
Landscape
Body N&V
Powertrain
N&V
Other
Areas
Interior (cabin) and exterior noise
Noise due to surface vibrations of
components such as crank case, fuel
pump, manifold,covers...
Brakes (squeal, for example)
Tires (cavity resonance)
Engine mounts (vibration isolation)
Fuel tank vibrations
…..

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Why SIMULIA for N&V

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Unified FEA for Multiple Attributes System-Level Analyses
Durability -- Speed bump analysis Durability -- Pothole analysis
Crash -- USNCAP Frontal Impact 35 mph, etc.NVH -- Modal Analysis

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N&V Capabilities in Abaqus
Complete set of linear dynamic
analysis procedures
• Natural frequency extraction
• Complex frequency extraction
• Steady state dynamics
• Transient modal dynamics
• Substructures
• Structural Acoustics
• Random Response Analysis
• Nastran-to-Abaqus
translation
Support for industry-unique
features:
• Preload effects, including
contact/friction
• Rolling tire effects
• Acoustic-structural coupling
• Frequency-dependent
behavior
• Damping options
High performance SIM
architecture
• AMS eigensolver with SMP
parallelization support
• AMS eignesolver with
GpGPU support

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Key differentiators of Automotive NVH in Abaqus
• With increasing degrees of freedom (dof)
• With increasing modal content
• With increasing modal response and multiple load cases
• With large retained mode and retained dof substructures
Performance
• Customer features consistent with “Best in Class” offerings
• General matrix representations
• Full damping representations
• Connection with other softwares (e.g. AVL / EXCITE)
Functionality
• Nonlinear / Unsymmetric effects
• Frequency-dependent behavior
Advanced mechanics
(“standard” feature to be)

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Performance

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AMS eigensolver
 Dramatically faster in medium- to large-models ( > 1M DOF) and large number of modes ( > 500)
 Benefits to other classes of problems including noticeable speed improvements even with small models
 13.7M DOF Vehicle Body Model: 600Hz cutoff frequency, 5190 structural modes with selective recovery, 266 acoustic
modes with full recovery, and 266 RHS vectors (residual modes) Intel Westmere-EX (4x10 cores) with 128GB memory
1
1.8
3.1
4.6
6.1 6.2
5.7
1
1.95
3.75
6.7
11 11.3
9.6
0
2
4
6
8
10
12
0
50
100
150
200
250
300
1 2 4 8 16 24 32
SpeedupFactor
Wall-Time(min.)
Number of Cores
FREQ Time (6.12)
AMS Time (6.12)
FREQ Speedup (6.12)
AMS Speedup (6.12)

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Example 1: 13M DOF
Powertrain Model
• Machine Information
– Intel Xeon Westmere X5690 (3.4GHz)
– 2x6 cores
– 96 GB memory
– 1.5TB disk space
• Model Information
– 13M DOFs with free-interface
– Number of retained DOFs: 1188
– Number of dynamic modes: 490 (below 10kHz)
– Substructure size: 1678
2.35 1.70
9.70
0.003
9.06
1.94
0
5
10
15
20
25
Abaqus 6.13 Abaqus 6.13
Conventional AMS-based
Wall-Time(hrs.)
Condensed Operators
Dynamic Modes
Constraint Modes
Frequency Extraction
Selective recovery
~14x

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Example 2: 10M DOF
Vehicle Body Model
• Machine Information
– Intel Xeon Westmere X5690 (3.4GHz)
– 2x6 cores
– 96 GB memory
– 1.5TB disk space
• Model Information
– 10M DOFs with free-interface
– Number of retained DOFs: 336
– Number of dynamic modes: 571 (below 300Hz)
– substructure size: 907
0.48
1.48
4.71
0
1
2
3
4
5
6
7
Abaqus 6.13 Abaqus 6.13
Conventional AMS-based
Wall-Time(hrs.)
Condensed Operators
Dynamic Modes
Constraint Modes
Frequency Extraction
Full recovery
~4x

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GPU Acceleration of the AMS Eigensolver
 6.14 AMS can utilize fast GPU
devices
There are three AMS phases
As the first release, only AMS
reduced eigensolution phase can
use GPU devices
Two other phases (AMS reduction
phase and AMS recovery phase) will
be supported in the next releases
AMS Recovery Phase
- Recover full/partial eigenmodes
AMS Reduction Phase
- Reduce the structure onto substructure modal subspaces
AMS Reduced Eigensolution Phase
- Compute reduced eigenmodes
AMS

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GPU Acceleration of the AMS Eigensolver
9M DOF Full Vehicle Model (10,743 eigenmodes below 800Hz)
Hardware: Sandybridge (2x8 cores), 2 NVIDIA K20X (Kepler)
1.00
1.50 1.54
1.00
2.30
2.39
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0
200
400
600
800
1000
1200
1400
6.13 6.14 6.14
16 Cores 16 Cores + 1 GPU 16 Cores + 2 GPUs
Speedup
ElapsedTime(sec.)
STD Time
AMS Time
STD Speedup
AMS Speedup

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Functionalities

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Linear Problems with Nonlinear Preloading
 Numerous examples demonstrate the importance of nonlinear effects
 Expanding on traditional Abaqus domains
 Tires
 Suspension
 Brakes
 Powertrain
 More accurate solution due to
 Nonlinear geometry
 Inertial effects
 Structural-acoustic coupling

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Front Corner Module Modal Analysis
 Goal is to capture accurate stiffness and modes
Nonlinear:
 Brake lining/pads/contact
 Shock spring
 Shock damper
 Shock bushing
Linear:
 Upper and lower arms
 Knuckle
 Anti-sway bar
Shock spring assembly frequency (Hz)
Suspension system
test (Hz)Mode
Linear
analysis no
preload
Abaqus preload
prescribed
Spring first axial 34 70 70
Spring second axial 100 132 131
Spring third axial 164 192 192

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Unsymmetric Dynamic Substructures
 Stiffness matrix can be unsymmetric
 Viscous damping matrix can be unsymmetric
 Important use case: Substructure representation of rolling tires
 Substructure generation for the base state obtained from the steady-state transport analysis of a
rotating tire in contact with the road
 Stiffness matrix can be unsymmetric due to the contact friction
 Viscous damping matrix can be unsymmetric due to the Coriolis terms
 Abaqus workflow for tires:
Nonlinear static analysis of a
stationary tire including
inflation and contact footprint
calculation
Steady-state transport
analysis of a rolling tire
Generation of an
unsymmetric dynamic
substructure for a
rotating tire
Using tire substructures in
the full vehicle simulations
Linear dynamic
analysis of a single tire

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Example: Frequency Response of a Tire at 60 km/h
FE model: 430 K degrees of freedom
Substructure: 180 dynamic modes, 2 retained nodes
FE model compared with tire substructure models
Significantly different results for rotating vs. stationary

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Full Vehicle with Rotating Tire Effects
 3.4 M degrees of freedom
 Structural material damping
 3,200 modes extracted
 Rotating tire effect taken into account using unsymmetric substructure
 AMS eigenvalue extraction and modal frequency response analysis

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Rotating Tire Effects
 Stationary tire (blue) vs. rolling tire (red)
 Roof vertical deflection
 Tire patch lateral response
Dramatic
differences

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Brake Squeal Analysis
Complex Frequency Solver: A single-bore disc
brake with a low frequency squeal at 2.9 kHz
Animation
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
-200 -100 0 100 200
Real Part of Eigenvalue
Frequency(Hz)
mu_a = 0.0
2.9kHz
Positive values indicate
squeal modes

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Brake Squeal Analysis
Nonlinear Transient Approach using Abaqus/Explicit
Apply
pressure
Maintain pressure
1.E+02
1.E+03
1.E+04
1.E+05
0 1 2 3 4 5 6 7 8 9 10
Frequency (kHz)
VelocityAmplitude
2.9kHz
Answer 3864

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1. Abaqus provides substructures (or linear elastic bodies) for crankshaft, engine block, etc.
2. AVL / Excite (Power Unit) provides nonlinear joints/bearing/mounts with gas forces and piston and timing drive impact forces;
the nonlinear bearing forces and moments can be calculated due to actual dynamics of parts of the assembled multi-body
system.
Substructure – Abaqus-Excite Workflow

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Squeak & Rattle simulation
 Challenges
 Predict squeak & rattle (S&R) using simulation
 Products
 Abaqus/Standard
 Methodology
 Linear Dynamics procedure
 Connector elements used as sensors
 Scripting to automatically create connectors
 Benefits
 Innovative use of connector technology to predict S&R accurately IDIADA, Spain, SCC 2011

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Noise & Vibration simulation
 N&V simulation enabled cheaper and
faster with AMS
 Transient Dynamics
Including fatigue analysis

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 Road Noise Simulation with Tires Modeled as Substructures
 The tire model needs to have a fine mesh to capture high frequency content, a deformable wheel
(significant after 300 Hz or so), and the tire acoustic cavity (significant above 200 Hz).
 The tire model thus calibrated will need to be converted to substructures before using in an
implicit dynamics simulation or steady state dynamics simulation along with the vehicle model.
 Abaqus-Adams Workflow for Full Vehicle
 Insert Abaqus substructures in Adams for calculating time transient load data at the attachment
points.
 Perform transient linear/nonlinear dynamics and/or steady state dynamics with Adams loads. For
example, friction with strut is an area of potential energy loss that could be critical.
 Weakly and Strongly Coupled Structural-Acoustics
 Lanczos or AMS uncoupled modes approach for weakly-coupled cases
 Lanczos coupled modes approach for strongly-coupled cases
NVH Technology Trends

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Noise and Vibrations for automotive-umashankar

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