Altair NVH Solutions - Americas ATC 2015 Workshop

Altair NVH Solutions
Jianmin Guan
Director, Vibration and Acoustics Solutions

Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
2015 Altair Technology Conference Workshop
Agenda
1. Altair NVH Solutions
• Altair’s Multi-Physics NVH Solvers
2. Best In Class NVH Design Process
• Altair’s Full Vehicle NVH Solution
• An Overview of Stochastic Analysis
3. NVH Diagnostics Demo
• Modal Participation
• Grid Participation
• Transfer Path Analysis
4. NVH Director Demo
• Full Vehicle Assembly
• Running jobs on the Local Machine
• Running jobs on a Cloud Machine
• Integrated Diagnostics

“Our vision is to radically change
the way organizations design
products and make decisions.”
– James R. Scapa, Chairman & CEO, Altair

A comprehensive set of NVH solutions for upfront problem solving
• Full frequency, multi-physics NVH simulation capabilities
• Superior user experience in a highly integrated, automated framework
• Population performance based assessment, instead of single sample
• Optimization based design, instead of experience based design
Altair’s NVH Vision

1. Full vehicle simulation
• Linear and frequency domain
• Non-linear and time domain
2. Root cause diagnostics
• Leverage all advanced diagnostic result types
• Integrated environment for fast and focused investigation
3. Sensitivity and forcing management
• Strategy for managing key transfer paths for each NVH loadcase
• Target ranges based on full vehicle modeling or historical data
• Understanding of good design practice
4. Stochastic population simulation
• Able to capture worst case combinations of ‘error states’
• Has a good framework for proper test/CAE correlation
• Uses population based performance metrics
5. Optimization
• Concept optimization
• Detailed optimization
6. Effective tools
• Handle complex tasks in a robust fashion
• Enable effective implementation on all programs
6 Key Elements of a Best in Class NVH Design Process

• FE Linear Dynamics (OptiStruct)
• FE based (direct or modal) frequency domain analysis
• Fully integrated automated multi-level eigensolver (AMSES)
• Fast large scale modal solver (FASTFR)
• FE based (direct or modal transient) time domain analysis
• Poro-elastic Material (AlphaCell)
• Boundary Element (Coustyx)
• Fast Multipole solver
• High Frequency (SEAM & EFEA)
• Statistical Energy Analysis (SEA) & Energy Finite Element Analysis
(EFEA)
• MBD based non-linear time domain analysis (MotionSolve)
• CFD based, flow induced noise analysis (AcuSolve)
Altair Multi-Physics Solvers

OptiStruct is the most feature rich solver for NVH
Process enhancements
• We added many features that made it easier and
faster for NVH engineers to get their jobs done more
robustly
Diagnostics / root cause analysis
• We injected many decade‘s practical experience into
develping diagnostic capabilities that help solve real
world problems

Significant Features Unique in OptiStruct
Process enhancements
1. CMS super elements in one file
2. 2d plot elements for coarse display mesh
3. PBUSH w/ mass and rigid properties
4. Frequency dependent material properties
5. CDS superelements for stochastic simulation
6. Model update by ASSIGN, UPDATE cards
7. CMS SE parameter modification and optimization
8. Automated peak response output
9. Subcase specific modeling
Diagnostics / root cause analysis
10. Automated, one-step, TPA
11. Design sensitivity output in frequency response analysis
12. Fluid grid participation factors
13. Component modal participation analysis
14. Powerflow analysis
15. Free field radiated sound pressure (Rayleigh‘s Integral)

Automated peak response output
Peak Frequencies
 Number of peaks
 Minimum cutoff
 Minimum spacing
1. Identify peaks in frequency response during a baseline run
2. Output detailed results for peak response frequencies in the
same run
3. Peak control parameters:

1. All results needed for TPA analysis can be output during a
single frequency response run
2. Transfer paths can be determined by control volume definitions
3. Improvements to traditional TPA process:
 No need to make two separate runs
 No need to worry about matching forces and transfer functions
Automated Transfer Path Analysis

Acoustics Solvers

Transfer Matrix Method (TMM/FTMM) to predict vibro-acoustic response of multi-
layer systems composed by air-gap, isotropic solids and isotropic porous
media.
Multi-layer Acoustic System Performance
Matelys AlphaCell
Benefits:
• Direct export of multi-layer system study to FE format
• Adapts to the degree of complexity of the models based on
information available
Key Features:
• Simple and advanced models are available to describe the
behavior of porous materials:
• Delany-Bazley (1 parameter),
• Miki (3 parameters),
• Hamet (3 parameters),
• Attenborough (4 parameters),
• Johnson-Champoux-Allard (5-8 parameters),
• Woven and non-woven textiles.
• Supports a wide range of excitations:
• diffuse sound field
• single mechanical force
• rain on the roof (ISO 140-18)
• turbulent boundary layer

AlphaCell – Biot material data library for OptiStruct

AlphaCell – Impedance element data for OptiStruct/Coustyx

AlphaCell – Absorption, TL and IL data for SEAM

High performance acoustic analysis software for
simulating acoustic phenomena and optimizing
NVH performance.
Benefits:
• Built on FMM-BEM* technology
• Fast and accurate analysis (50x faster than standard BEM)
• Large models (1 Million unknowns)
• Broadband (Low-Mid-High) frequency analysis
• Parallel implementation
Key Features:
• Import options from file types: OptiStruct (fem), Nastran (bdf,
punch, op2), Ansys (rst, rfrq), Abaqus (inp, odb), Polygon and
Universal file formats
• Wide selection of boundary conditions
• Automatic generation of jumps and junctions
• Acoustic sources built-in
• Outputs: Sound Pressure, Sound Power, Sound Intensity,
Muffler Transmission Loss
Fast Multipole BEM Acoustic Solver
ANSOL Coustyx

High Frequency Solvers

Solution to evaluate the dynamic response of complex structures at mid and
high frequencies including interior noise and vibration, radiated noise, and
vibro-acoustic environments.
Statistical Energy Analysis (SEA) Solver
Cambridge Collaborative SEAM
Benefits:
• Only commercially-available software that provides a
complete statistical representation of the SEA response.
• Predictions of mean-response can be combined with
predictions of variance to set upper confidence intervals.
• Use of the upper confidence interval insures that new
products meet acoustic and vibration design objectives
Key Features:
• Very large models with thousands of SEA subsystems
• Calculation of coupling loss factors and modal densities
• Octave, one-third-octave, narrowband and percentage
bandwidth analysis
• Design sensitivity analysis
• Transient analysis
.

Energy Finite Element Analysis (EFEA) Solver
Key Features:
• Operating like a FEA solver but using different type of
variables based on energy, thus enabling simulations at
mid to high frequencies
• Processes which are already in place for developing FEA
models can also be used for developing EFEA models
• The CAD geometry can be used for developing
either a conventional FEA model or an EFEA model.
• The EFEA model is much coarser than the FEA
model. This is the result of solving a different type of
equations which are energy based (EFEA) instead of
displacement based (FEA).
• Both structural elements and acoustic elements are part of
the EFEA model.
• The simulation time is fast and that allows evaluating a
large number of design alternatives quickly.
Vibro-acoustic solver suitable for mid to high frequency
noise and vibration analysis using a finite element model MES EFEA

Transient and Low Frequency
NVH

MBD Vehicle NVH Solutions
Current NVH Solutions using
Multibody Dynamics Simulation
• Shift quality
• Ride quality
• Engine dynamics
Flexbody Analysis
ARRK – PRT Casestudy
ARRK – PRT Casestudy
Altair MotionSolve

Body Squeak and Rattle

Squeak and Rattle solution allows to identify the risk areas for squeaking and rattling early during the design
phase by integrating best practice methods into semi-automatic process tool and cutting down repetitive tasks.
It empowers engineers to calculate the relative displacement in time domain based on the user selected results.
Squeak and Rattle Director

Squeak and Rattle Director – Solution Overview
Embedded in HyperWorks environment, this tool:
• Implements a semi-automated procedure minimizing the amount of repetitive tasks
• Offers a comprehensive and efficient workflow
• Supports post-processing of results due to dynamic loads in time domain (ex. Road
test data) or pseudo-random signals
• Calculate dynamic tolerances, when dimensioning data are available
• Provides flexibility for incorporating customer specific data, for instance:
• Material database
• Dimensioning and tolerance
data
• Additional load cases
(thermal, quality feel, etc.)

CFD/CAA

Vehicle Interior Wind Noise
Noise Sources (0-2KHz):
1. Fluid Fluctuating Pressure causes window to vibrate which creates noise inside cabin
2. Fluid Borne Broadband Noise (quadrupole) that is transmitted through window/door seal
inside cabin
Transient CFD
Noise generated
by turbulent
flow
Transient CFD
Fluctuating Pressure
Fluctuating Pressure
mapped to Cabin NVH model
Altair AcuSolve

APA Software + HyperWorks Complementarity
OptiStruct
Full Vehicle
SEAM
EFEA
Powertrain
Coustyx
EXCITE Acoustics*
Radiated Noise
Coustyx
EXCITE Acoustics*
Wind Noise
SEAM
EFEA
Coustyx
Body &
Chassis
AlphaCell
CAEfatigue
VMAP
NVH
OptiStruct has evolved over many years from an optimization product to a complete Nastran
replacement solver. The NVH offering in OptiStruct addresses many of the common user
applications, with APA products filling in the gaps for a more complete picture as shown below.
* Coming soon

Altair NVH Solutions
Full Vehicle NVH
Powertrain NVH
Body/Chassis NVH
Squeak & RattleWind Noise
Radiated Noise
Ride NVH
Brake NVH

Altair’s NVH Solution
A comprehensive set of NVH solutions for upfront problem solving
• Full frequency, multi-physics NVH simulation capabilities
• Superior user experience in a highly integrated, automated framework
• Population based performance assessment, instead of single sample assessment
• Optimization based design, instead of experience based design

6 Key Elements of a Best in Class NVH Design Process
• Linear and frequency domain
• Non-linear and time domain
2. Root cause diagnostics
• Leverage all advanced diagnostic result types
• Integrated environment for fast and focused investigation
• Strategy for managing key transfer paths for each NVH loadcase
• Target ranges based on full vehicle modeling or historical data
• Understanding of good design practice
4. Stochastic population simulation
• Able to capture worst case combinations of ‘error states’
• Has a good framework for proper test/CAE correlation
• Uses population based performance metrics
5. Optimization
• Concept optimization
• Detailed optimization
6. Effective tools
• Handle complex tasks in a robust fashion
• Enable effective implementation on all programs

• Full vehicle simulation is required in solving
strongly coupled problems
• Traditionally full vehicle simulation approach:
• Linear frequency domain FE analysis
• Worked reasonably well for low frequency
steady-state problems, such as idle shake
• Do not work well for transient phenomena, such as
impact harshness
• To overcome limitations of the traditional
approach,
• Nonlinear and time domain approaches are
increasingly applied for transient phenomena
• CFD and SEA are approaches for simulating high
frequency problems

Steady State Low Frequency Full Vehicle Simulation

2. Root Cause Diagnostics
Problem
ResponseWhich
Mode?
Which
Paths?
What
Power
Flow?
What
DSA?What
Energy?
What’s
Moving?
Which
Panel?
What
If…?

Modal Participation Visualization

Grid Participation Visualization

Response Studies using Grid Participation Data

Transfer Path Analysis – Contribution Bar Plots

Transfer Path Analysis – Contribution Colormap

Visualizing Energy Results – Contour at comparator levels
Viewing contour plots at different comparator levels can help better understand the
distribution of energy at different granularity levels.
Module (L2) level
FE Comp (L3) level
FE Element (L4) level

Visualizing Energy Results – Line, Sand dune and 3D Bar Plots
Line, Sand dune and 3D Bar plots are ways to visualize energy distribution over a
frequency range.
Percentage (%) is the default scale that works well in most cases since users are
typically not interested in the absolute levels of energy at each frequency

• Geometry transformation
• Modal animation review and mode
shape difference contour
• MAC of real modes, complex
modes, and ODS results
• Partial MAC to identify sub-
models responsible for correlation
issues
• CoMAC calculation and display
• MAC sensitivity studies by
excluding nodes or sub-models
based on CoMAC or PMAC values
• Frequency difference plot
New 13.0 Feature – Model Correlation Utility

13.0.111 Feature - Radiated Sound utility
• Support ERP and Radiated
Sound output
• Calculate sound power from field
pressure results
• Perform partial sum studies
• Broadband band plots
Sound Power at Receiver SideSound Power at Source Side
Sound Pressure at Node:7000023

• Full vehicle analysis can be complex, and
may not be the preferred tool for some class
of problems
• Managing sensitivity and force at key energy
transfer paths is another important tool
• Sophisticated process has been developed to
derive sensitivity and forcing target ranges
for individual transfer path on a given platform
of vehicles based on:
• Historical data from measurement or simulation
• Full vehicle model cascade
• Good design practice capable of delivering the
targets are often developed and documented
F
r
Ff
F
r
F
f
F
t
F
e

4. Stochastic simulation
• Stochastic simulation is the only way to fully
quantify NVH performance
• NVH problems are often ‘Error States’, which do not
happen, or happen in the same ways, on all vehicles
• A framework for proper test/CAE correlation
• Nominal to one sample comparison is not meaningful
• More robust estimates of response than the
nominal design
• A more robust estimate is the mean of a population
simulation
• Ways to implement stochastic simulation
• Loads randomization
• Geometry parameter randomization
• Advanced OEMs require stochastic results to sign
off vehicles

Capture worst case combinations of
‘error states’

Population based Performance & Robustness analysis
• Quantify noise factors in loads
• Quantify noise factors in vehicle components
• Identify control factors
• Perform Monte-Carlo simulation
• Evaluate vehicle population based metrics
• Optimize vehicle tuning

A framework for proper test/CAE
correlation
NVH - 49

Automotive vehicle population performance
Source: A. Duncan et al., 20013 SAE Noise and Vibration Conference ,Structure Borne NVH Workshop
2013 SAE NVC Structure Borne Noise Workshop
Slide 78
Frequency ( Hz )
Magnitude of 99 Structure Borne Noise Transfer Functions for
Rodeo’s at the Driver Microphone
Measurements from Kompella and Bernhard
( Ref. 8 ) 1993 Society of Automotive Engineers, Inc.

Automotive vehicle population performance
Slide 79
Frequency ( Hz )
Acoustic Scatter from Simulation of the
vibroacoustic behavior of a vehicle due
to possible tolerances in the component
area and in the production process.
© 2000 Society of Automotive Engineers, Inc.
Reproduced with permission from paper
by Freymann, et. Al. (Ref. 9)
12 dB Variation
Experimentally detected Scatter in low
frequency vibroacoustic behavior of
production vehicles.
Freymann, BMW NVH Scatter Results

Statistical view of Test/CAE correlation
Slide 95
FIG. 20. Comparisons of the stochastic computational model results with the experiments for the booming
noise. Graphs of the moduli of the FRFs in dB(A) scale: experiments for the 20 cars (thin gray lines); mean
value of the experiments (thick gray line); Mean computational model (dashed line); Mean value of the
random response (mid thin solid line); 95% confidence region: the upper and lower envelopes are the upper
and lower thick solid lines.
P/T Load
2nd Order
95% Upr
Nominal
50% Mean
95% Lwr
Non-Parametric Probabilistic Simulation; Soize, Durand, Gagliardini
CONCLUSIONS:
. The 95% Confidence Bands encapsulate the Measured Scatter of 20 Vehicles.
. Half-Bandwidth Scatter (between Mean and Upr 95%) is similar to K-B Half-Bands.
NOTE: The Method has Quantified the Model and Manufacturing Combined Uncertainty.

Population based performance
metrics

Nominal design performance from a statistical standpoint
Slide 97
FIG. 4: Computed booming noise inside a car vs. rpm, using only structure-borne excitation compared with the
measured value (brown bold). Thin dotted black: deterministic computation; green: median value; thin dotted
blue: lower bound with a 95% probability; dotted red: upper bound with a 95% probability.
P/T Load
2nd Order
Non-Parametric Probabilistic Simulation; Jund, Guillaume, Gagliardini
95% Upr
Nominal
50% Mean
95% Lwr
Test
Measurement
Author:
Focus of Correlation Effort
All Test Peaks in Band: Results imply a
Countermeasure is needed.

Mean performance is a more robust metric of design

Stochastic analysis as an enabler for upfront design
1. Better ability to capture potential NVH problems
1. Problems are identified based on multiple analytical vehicle samples that
show high peak behaviors
2. A good example is the case where two subsystem modes are not aligned
based on the nominal design, but can be aligned when variation is
introduced in modes
2. Better ability to deal with lack of design details
1. Lack of design details – NVH performance needs to be robust to a range of
floor bead designs
2. Uncertainty in tire forces - NVH performance needs to be robust to a range
of tire forces
3. Better understanding of key subsystem design metrics affecting the
robustness of vehicle NVH performance
1. Help setting subsystem targets

5. Optimization driven design
ConceptPhaseDetailedDesign
System Level Subsystem/Component Level
Topology
High number of DV
Global stiffness responses
Design Space
Size
Medium number of DV
NVH responses
Concept Model
Topology/Topography
High number of DV
NVH responses
Reduced Model
Size/Shape
Low number of DV
NVH responses
Reduced ModelSize/Shape
Medium number of DV
NVH responses
Detailed Model
Body Gauge
Reduce mass
Topography
Panel Acoustic Response
Size/Shape
Mount Locations
Mode Tracking
Topology
Concept Structure and
loadpath definition
FreeSize
Highlight reinforcement
patterns

Full Vehicle Optimization
Model
1. A very detail full vehicle model consisted of over 40
components and had around 12 million degrees of freedom
2. Reduced component CMS SE models were created
Loads and Response
1. Rough road profile input is applied at tire patch points.
2. The acoustic response at the driver’s ear was captured and
the FRF response plotted.
Minimize thickness of damping material applied to panels
1. Front of dash
2. Front floor pan
3. Rear floor pan
4. Tail panel
5. Both quarter panels
6. Both rear wheel house
Result
1. Significant reduction at Driver’s Ear for rough road boom
around 102 Hz

6. Effective Tools – NVH Director
 Assembly
 Event simulation management
 Post-processing and problem diagnostics
 Optimisation and stochastic simulation
 Multiple discipline simulation framework
 Key enabler for consistent best practice application on all programs

NVHD - for superior user experience
NVHD Main Key Features:
Simplifies Full Vehicle Simulation
• Facilitates modeling of all vehicle subsystems
• Provide physical root cause understanding
• Apply the entire NVH toolset for effective problem solving
Model Build Time Reduction
• Coarse display mesher
• Cavity representation / coupling checking tools
• Enhanced ID management
Object Oriented Assembly Environment
• Manage multiple, interchangeable, solution representations for each subsystem
• NVH-friendly lumped parameter modeling and coordinate system definition
• Manage multiple connection property sets selectable based on analysis needs

NVHD - for superior user experience
NVHD Main Key Features:
Process Guided Loadcase Setup
• Step-by-step loadcase setup processes
• Solver load cards automatically generated
• Spindle loads utility with principal component
Integrated Result Post-Processing and Visualization
• A full set of integrated post-processing utilities
• Results can be accessed instantly based on diagnostic need
• Model correlation utility (MAC)
Optimization
• Identify top sensitive design variables thru post processing and sensitivity
analysis
• Use reduced component representations for non-design areas
• Facilitates size, shape, topology, topography optimizations
• CMS SE modal parameter optimization in residual run

NVH Director Demo

Summary

The NVH Director solution is packaged with
additional services to ensure a successful
implementation
1. Training
• Quick start video
• Instructor-led class
• Tailored course
• On-site expert help
2. Customization
• Generic
• Special request
3. Project Engagement
• Engage Altair ProductDesign NVH experts
to execute a customer project
NVH Director Solution Package
HyperWorks is backed by deep
engineering knowledge and broad
domain experience other solver
companies don’t have
Altair’s ProductDesign is a global
500 person strong engineering
consultancy
ProductDesign uses HyperWorks
to solve cutting edge and often
specialized design issues every
day and across multiple industries

Benefits from the Altair Partnership
Altair is the industry leader in providing NVH simulation solutions
• Veteran industry experts from leading OEMS are on staff
• Unique insight on industry trends
• Proven capability in delivering best in class NVH features
Altair has the world class support
Altair has a highly capable Product Design team
Altair has many partner solutions
• Ansol Coustyx – FMM BEM
• CC SEAM – SEA
• Matelyse AlphaCell – Porous Material Modeling

Thank you!

Altair NVH Solutions - Americas ATC 2015 Workshop

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