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






• Population performance based assessment, instead of single sample


Altair’s NVH Vision



• 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 SEAMBenefits:

• 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 dynamicsFlexbody 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 PressureFluctuating 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

NVHOptiStruct 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 NoiseRide NVH

Brake NVH



Altair’s NVH Solution




• Population based performance assessment, instead of single sample assessment




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

rF

f

F

tF

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 paperby 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

Concept

Phase

Deta

iled D

esig

n

System Level Subsystem/Component Level

TopologyHigh number of DV

Global stiffness responses

Design Space

SizeMedium number of DV

NVH responses

Concept Model

Topology/TopographyHigh number of DV

NVH responses

Reduced Model

Size/ShapeLow number of DV

NVH responses

Reduced ModelSize/ShapeMedium 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

FreeSizeHighlight 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 DIAGNOSTICS DEMO

NVH - 62



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

http://www.altairproductdesign.com/Default.aspx

http://www.altairproductdesign.com/Default.aspx



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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