Altair HTC 2012 NVH Training

An Innovative Solution for True Full Vehicle
NVH Simulation
Jianmin Guan
Innovation Intelligence®
May 15, 2012

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

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Simulation, predictive analytics and optimization leveraging
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for engineering and business decision making


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•  Powerful business model with unmatched customer value
•  Depth and breadth of the overall solution set
•  Market defining optimization technologies
•  Unparalleled performance and measurability
•  Unique ability to leverage high-end services
to drive next generation solutions

•  Strong global organization that can meet
the needs of the most demanding customers
worldwide

No other vendor offers the completeness
or robustness of the Altair solution set


Agenda

1. Introduction Altair
2.  CAE driven vehicle NVH development
•  Unlocking values in CAE
•  Modal participation
•  Grid participation
•  TPA
•  Integrated diagnostics
4.  Introduction to true full NVH vehicle simulation
•  Meshing
•  Assembly
•  Loadcase setup
•  Full vehicle optimization
5.  Summary and recap
6.  Q&A


CAE Driven Vehicle Development


A Generic Full Vehicle NVH CAE Process Flow
Batchmeshing
Renumber FE Model
Finite Element Model
Acoustic Model
CAD files Display Model
Modal Model (CMS)
FRF Model Configuration Specification
(From a PLM system) Lumped Parameter Model Lumped Parameter Models Assembly Hierarchy
Dynamic Reduction Symmetry Components
Representation Variation
Complex Connector
Component Component Assembly Connector Variations
Model Files Constraint Variations
Local Coordinates
Connectivity Checking

Assembly Files
(MDL, XML or other)

NVH Director Loads Library
Force Identification
Principle Vector Analysis
Input/Response Points
Report Loadcase Post-Process Request
Variation realization
Model Checking
Model Unit System
Job Submission

Optimization Post H3D
Processor Solver Radioss/Nastran
DOE (HG/HV)
Deck

Post-Solver Analysis Auto Output Peaks
Integrated Visualization Modal/Grid Participation
Transfer Path Analysis Energy Distribution
Job History and Job Folder Design Sensitivity


NVH Problem Diagnostics

Problem
Which Which
Response
Mode? Paths?

Which What
What’s Power
Panel?
Moving? Flow?

What What
What If…? DSA?
Energy?


Modal Participation Visualization


Response Studies using Modal Participation Data


Benefits of ‘Response Studies’

§  Find the upper limit of the selected output data’s impact on the response
•  If it is too small, you may decide not to bother with optimizing the local
structure there
§  Identify the impact of the selected output data over the entire frequency
range analyzed
•  improvement at one
frequency is
accompanied by
degradations at others
•  knowing the impact over
the whole frequency
ranges helps to ensure
that the solution is a
good overall solution


What is Acoustic Grid Participation?
§  Acoustic Grid Participation is a way to break down an acoustic response to contributions
from grids on the fluid-structure interface
•  Physically, the body structure grids vibrate, exciting the interior cavity fluid grids, eventually generating an acoustic
response at Driver’s ear
•  Structure grid participation gives participations from the body structure side of the fluid-structure interface
•  Fluid grid participation gives participations from the interior cavity side of the interface

§  The word ‘acoustic’ in ‘acoustic grid participation’ relates to the fact that the response is
acoustic. Both Structure and Fluid grid participations are acoustic grid participations
Acoustic Response
at Driver’s Ear
Structure Grid Participation
from Interface Grids on Structure

Fluid Grid Participation
from Interface Grids on Interior Cavity


Grid Participation Plotting Capabilities

Fluid Grid Participation

Structure Grid Participation


Grid Participation Visualization


Panel Participation Visualization


What is Transfer Path Analysis?

•  Transfer Path Analysis (TPA)
is a technique to break down the total response to
partial contributions from attachment points under
operation loads

•  Partial contributions to total response
are calculated by multiplying transfer function with
force transferred through each attachment point

•  TPA is the key NVH diagnostic tool in the mid-
frequency range
Modal and Grid participation are more useful for
understanding low frequency NVH problems. But in F
r F
mid-frequency, there are often too many modes or r
grid areas participating, and a path based approach Ff F F
Fe f t
becomes more convenient


Transfer Path Analysis – Contribution Bar Plots


Transfer Path Analysis – Contribution Line Plots


Transfer Path Analysis – Contribution Colormap


Transfer Path Analysis – Response Studies


Energy Distribution


Design Sensitivity Analysis


Engine Order Analysis


True Full-Vehicle Simulation


Trimmed body based optimization example

Panel Participation Plot at peak
frequency Top Five Contributors

+

Fluid Structure
coupling

Design changes to the
contributing parts

Identify peaks
P/F Plots & V/F Plots

P/F Plots meeting target


Benefits of true full-vehicle simulation
1. Simulation of real-world events
•  Loadcases directly simulate customer usage experience
•  Problems related to specific loadcase/response are identified
•  Clear understanding of cost and benefit
•  Can be used to drive physical prototype development

2. Physical root cause understanding
•  Clearly identified source-path-receiver
•  Most effective solutions often come from source reduction
•  Understanding of noise/vibration energy transfer paths
•  Most sensitive parts & cost effective solutions can be identified
•  CAE model can be validated through trend prediction
•  Force distribution for subsystem level analysis and optimization can be generated

3. Ability to apply the entire NVH toolset
•  Effective problem resolution requires using the right tools
•  Low frequency – modal alignment and contribution analysis
•  Mid frequency – transfer path, point mobility, and panel analysis
•  Effective isolation
•  Mass damper and tuned mass dampers
•  Mastic or beads on panels
•  Optimization


True full vehicle optimization example
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.  A unit torque load was applied to the powertrain over the
given frequency range.
2.  The acoustic response at the driver’s ear was captured and
the FRF response plotted.

Roughly 2000 full vehicle design variables were defined
1.  Plate thickness for the body and all components (app. 950
values)
2.  All vehicle tuning parameters that contained stiffness values
(app. 180 values)
3.  The modal tire properties (app. 720 values) (special
program)
Result
1.  Limited success with using only the top 50 DESVARS from
the body
2.  Good success with top 50 DESVARS from the body and the
top 50 tuning parameters DESVARS


NVH Director Features


Full vehicle simulation methodologies

Methodology Trimmed
Body
Single
file
vehicle Multi-‐include
vehicle True
full-‐vehicle
Features trimmed
body some
suspension
FE keep
subsystem
FE
in
its
own
include an
object-‐based
assembly
environment
test
based
loads
on
body some
PT
FE assemble
the
right
includes
to
form
seamlessly
manage
multiple

vehicle
model representations
test
based
PT
and
suspension typically
do
not
include
tire
or
only
a
crude
assembly
definition
seamlessly
manage
multiple
connection

driveline exists states
seamlessly
manage
ID
conflicts
functionality
to
create
reduced

manage
loadcase
manage
hardware
and
analysis

manage
job
submission
and
job
history
Advantage able
to
iterate
on
trimmed
body able
to
iterate
on
susp.
and
PT
able
to
iterate
on
susp.
and
PT
able
to
iterate
on
all
details
of
a
full

somewhat somewhat vehicle
subsystem
handling
is
somewhat
Subsystem
handling
is
fully
modularized
modularized
Can
easily
mix
detailed
and
reduced

representations
Can
quickly
customize
model
setting
based

on
loadcase
needs
Can
quickly
review
and
rerun
past
analysis
Disadvantages cannot
iterate
on
susp.
&
PT
very
difficut
to
connect
difficult
to
manage
ID
conflicts

changes subsystems
given
the
details betweem
subsystems
requires
high
cost
of
prototypes have
to
keep
one
model
for
each
difficult
to
manage
conflicts
between

loadcase detailed
FE
and
reduced
models
cannot
support
upfront
issue
very
difficut
to
update
or
tune
difficult
to
check
for
errors
identification subsystem
models


HyperWorks roadmap to effective optimization

1. Not enough time left in a design cycle for optimization

§  Takes too long to build the model CAD-CAE exchange, batchmeshing, assembly

§  Takes too long to run analysis jobs Use reduced comp. models, CMS, FRF

§  Takes too long to diagnose problems Results served based on relationships

§  Takes too long to run optimization jobs Optimize with non-design parts reduced

2. Too complex to manage
Multiple discipline optimization
§  Conflicting requirements from different disciplines/attributes
§  Inconsistent discipline/attribute model contents
Use common assembly definition
§  Different solvers
Radioss has multiple physics solutions
§  Takes too long to solve
Reduce solution time, better understanding of sensitivity
3. Not sure about model correlation
Ensure common design content and physical behavior


HyperWorks NVH Director – A complete solution

BatchMesher

Component Model
meshing Preparation
Hypermesh

Assembly
Tool Model
Assembly

Radioss

Optimization
HyperGraph NVH
DOE & Simulation
HyperView Tools
Stochastics

OptiStruct
&
HyperStudy
Results
Visualization
HyperView

A complete solution for NVH
Process
Manager
Templates


How you can access the NVH Director

Release:
NVH Director was officially released in the 11.0 SA-101-NVH
patch, and will be a part of future HW patch releases
•  It is currently only available on the Win64 and Win32 platforms
•  Linux64 and Linux32 are planned for release in the 11.0 SA-130 patch

Access:
1.  HyperMesh
•  Select Engineering Solutions -> NVH
(Radioss) or NVH (Nastran) User Profile
2.  HyperGraph/HyperView
•  Load the NVH Utilities preference by
selecting File -> Load -> Preference
•  Highlight NVH Utilities and click ‘Load’


Massive efficiency gains through integration

1.  Interface to PLM systems
•  Geometry and non-geometry CAD data

2.  Subsystem modeling
•  Batch meshing, acoustic cavity and coarse display meshing
•  Lumped parameter model, NVH coordinate system creation

3.  Assembly
•  Seamless switching of module representations and connections states
•  Configuration management (future)

4.  Event simulation management
•  Loadcase and Analysis object management
•  Job submission and job history object management
5.  Post-processing and problem diagnostics
•  Leverage model and assembly data for post-processing
•  Serving diagnostic results based on relationship to response

6.  Optimization and stochastic simulation
•  Identify sensitive parameters thru problem diagnostics
•  Utilize reduced models for non-design space to reduce runtime
7.  Multiple disciplinary simulation framework
•  Utilize common assembly definition for multiple discipline


Job submission


Job manager


Multiple-Discipline Modeling and Optimization Process
(This is a framework vision; only NVH has been completed with Crash coming next)

Common CAD Content Common Assembly Definition Common Connection Definition
Unique Component Representations Unique FE Realizations

Common NVH, Crash, Durability, MBD… Common NVH, Crash, Durability, MBD…

Unique Simulation Events Multiple-Discipline Optimization One Updated CAD Content

NVH, Crash, Durability, MBD…


Modularized management of vehicle subsystems

1.  Subsystem representations
•  Seamless switching among multiple representations (FE/Modal/FRF) for
each subsystem
•  Subsystem can be easily updated by pointing to a new representation file
2.  Connector states
•  Multiple connector property states can be selected use based on loadcase

3.  Visual display in 3D graphics
•  Switch between a full FE or a coarse mesh display
•  Full show/hide/isolate/find unattached capabilities
•  Multiple display modes for connection/input/response/plot points
4.  ID management
•  Validate ID range assigned to each subsystem to ensure it is not in
conflict with other subsystems (inter-module) and with its include file
(intra-module)
5.  Left/Right symmetry (future)
•  Synchronize definitions of symmetrical (left to right) subsystems
6.  Assembly data in nested xml files
•  Assembly information can be saved in sub-xml files
•  Allows sub-assemblies to be owned by responsible activities for quick
updates


Network view of vehicle model


Specialized functionalities designed to simplify complex
NVH model creation

1.  Templated lumped parameter models
2.  Joints modeling using enhanced CBUSH
3.  NVH local coordinate systems
4.  Templated loadcase creation
5.  Acoustic cavity meshing and fluid structure interface
6.  Coarse meshing
7.  Batch meshing and welding of subsystems
8.  Door seals and windshield bonding
9.  Mass trimming
10.  Subsystem model preparation
•  Add spider
•  Add plotel
•  Repositon/re-orient
•  Assign damping
•  Calculate mass (future)


Radioss reduces runtime for full vehicle NVH solution

1.  AMSES (Automatic Multilevel Substructuring Eigen Solver)
•  Comes with the RADIOSS solver with no additional cost
•  Runs on Windows (All new PC’s are multi-core with large RAM)
•  Handles unconnected structures

2.  Automatic result filtering (PEAKOUT)
•  Detailed results for peak response frequencies in a single run
•  Without this, since frequencies with peak Dynamic Response are not known
ahead of time, a second run must be made to get detailed results output

3.  Advanced Dynamic Reduction Techniques
•  CMS Superelement (free, fixed, and mixed boundary)
•  CDS Superelement (FRF based)

4.  Significantly Enhanced Bushing Element (PBUSH and PBUSHT)
•  Directional mass and inertia can be defined, in addition to directional stiffness
and directional damping.
•  RIGID option for stiffness dofs added
•  Simplifies joint modeling by encapsulating multiple elements into one CBUSH


Innovative problem diagnostic and study capabilities

1.  Innovative approach for serving results based on
physical relationships
2.  A full set of integrated post-processing utilities
•  Modal/Panel participation from both system and CMS SE
component modes
•  Grid participation
•  Transfer path analysis
•  Engine order analysis
3.  Response study – investigate effects of varying
modal, grid participation, transfer function, force, etc
4.  Enables engineers to
•  Obtain a full understanding of physical root causes
•  Leveraging mathematical cause-effect relationships and
•  Identify sensitive parameters through quick what-if studies
•  Significantly reduces physical testing by running many
iterations in CAE simulation
•  Improves the value of testing by helping the engineer learn
more from simulation.


Latest technologies for superior user experience

1.  Specialized NVH mesher
•  Acoustic cavity mesher, coarse display mesher

2.  Browser technology
•  Data views, context menu, show/hide, interactivity with 3-d window
3.  Connector technology
•  Multiple property sets, checking thru realization
4.  Data manager technology
•  Link to PLM system for geometry and non-geometry CAD data
•  Assembly definition xml database

5.  Object oriented assembly environment
•  Modularized model management
•  Network view (future)
6.  Name based entity reference
•  Modules, points, connections, local coordinate systems

7.  Templated model/loadcase generation capabilities
8.  Process manager
•  Guided loadcase setup

9.  Result math
•  Enables rapid NVH data manipulation


Streamline work flow by effective data management

1.  Interface to PLM systems
•  Geometry and non-geometry CAD data

2.  Altair data manager is the backbone of
the assembly environment
•  Representation file hierarchy, versioning (future)
•  XML assembly definition files

3.  Import/export capability of key user data
through ascii csv files
•  Hard point locations
•  Connection properties
•  Module id ranges

4.  Jobs history
•  input/result files (future)
5.  Diagnostic data linked to responses


FE vs. Module Environments

FE Module
1.  Model Entities - Elements and 1.  Model Objects - Modules,
Nodes etc. Representations, Tagpoints, LP
templates etc.

2.  IDs – Managed directly in session 2.  IDs - Kept track in assembly mode,
and managed directly in single
module mode

3.  Model – Single model saved in 3.  Model – Assembly saved in .xml;
binary (.hm) or ASCII (.bdf) multiple solver (.dat) files can be
generated instantly

4.  Loadcase - Single event 4.  Loadcase - Multiple event
simulation simulation

5.  Database – HM database 5.  Database – Data Manager plus HM
database

6.  Process Objects – None 6.  Process Objects – Analyses, Jobs
etc.


Meshing

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Acoustic Cavity Mesher

§  Capability to preview cavities found by
auto scan
§  Separate hole and gap control
§  Generates congruent mesh with seat
cavities or MPCs to couple with
existing seat mesh
§  High quality tetra or mixed hexa/tetra
mesh
§  Creates hole elements that can be
modified to customize cavity definition

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Input for Cavity Creation

•  Structural components (no limit on number of elements)
•  Seats components – seats
ü Node to node remesh
ü MPC to existing mesh
•  Element size
•  Gap patch size
•  Hole patch size
ü Create hole elements – this gives user the ability to select what holes get patched

- 50


Preview of Found Cavities

•  Browser is used to list found cavities, grouped
structural and internal.
•  Browser can be used to modify appearance of
associated elements.
•  Structural cavities sorted by size; have ability
to limit number.

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Mesh Cavities

•  Browser can be used to select which cavities in
preview should be meshed.
•  Can create non-conforming hexa-tetra or all-tetra
meshes.
•  Can input response points from CSV file or use
existing nodes (thus, maintain ID).
•  Can specify minimum values for resulting hexa
jacobian ratio and tet-collapse

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Cavity

Windshield

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Radioss Auto Coupling using the ACMODL Card

Coupling can be controlled by a user
defined search box
Search can also be limited to user
selected node sets


Fluid-Structure Coupling Verification

§  Do not assume perfect coupling from default search parameters
§  Radioss automatically generate an .interface file
§  This file can be loaded into HyperMesh to verify fluid and structural
wetted surface Coupled
Elements

Uncoupled
Elements


Coarse Display Mesher

Original detailed FE model: 640k grids Coarse display model: 7200 grids

§  Coarse display model is only1-2% of the original detailed FE
model size
§  Used for pre- and post- visualization
§  Plate PLOTELS – PLOTEL3 and PLOTEL4 Elements
§  Supported by HyperMesh and the Radioss solver
§  Much smaller results files (tens of GB to less than one)
§  Never have to worry about results being separated from the
display model
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Assembly

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NVH Director Features – Tutorial

This exercise takes the user through the main steps and features of NV Director

Step 1: Start NVH
1. Select Engineering Solutions > NVH > Radioss from the User Profile window.

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Step 2: Define Assembly Hierarchy 2. From any view of the Assembly Browser, right-click and select
1. From the HyperMesh View menu, select Assembly Browser.
Create Module.

This opens the Module Create dialog.
A file save warning message will be displayed informing you that
the complete assembly database can only be saved in the XML
format as shown in step four of this tutorial.

3. Enter a module name in the dialogue, and then click OK. Repeat
the process to create all root level modules for the assembly. Expand
the assembly by clicking on the ‘+’ box next to Module Model.

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Step 3: Load an Assembly Definition XML file This opens the XML Import dialog.
1. From any view of the Assembly Browser, right-click and
select Import XML.

2. After naming the module, you need to import an XML file.
This should be an assembly database file that you exported
from the NVH Director. Click on the file folder icon to navigate
to a folder where the .xml file is located. Select the file and
click OK to load the file.
The assembly information will be loaded into HyperWorks.

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Step 4: Save an Assembly Definition XML file
1. To save the Assembly definitions in XML files, click on the File View icon.

Note: The Preserve option saves an assembly XML file along with a set of
nested subassembly files (similar to include files.) The Merge option saves
the assembly file with all subassembly files merged into it.

Subassembly files can be specified by clicking on the ‘-‘ icon in the XML
file path column. Navigate to the desired folder and specify a file name.
Export of subassembly files can be controlled by checking/unchecking of
the check box in the Export column.

Note: the Save XML option is enabled only in the File View to ensure that
you are aware that the subassembly files are over-written.

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Step 5: Define Module Representations 2. Select a module from the drop down menu marked Module to
1. Right-click on any module and select Manage Module >
select a different module. To create a representation for the
Representations. This brings up the Module Manager tab, and the
selected module, right-click inside the top part of the
Representation sub-tab is shown.
Representation tab.

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3. Select Add to add a representation.

6. Aside from file based representations, a templated Lumped
Parameter (LP) representation can also be defined using the LP
templates included in the NVH Director, or user created templates.

7. Select one of the representations to be the active Display
4. On the newly created representation change the module
description, if desired. A default description is created, which or Analysis representation by checking the appropriate
you can edit. radio buttons.
5. After a representation has been added, use the Type field 8.  Repeat the process by selecting another module through the
to select an appropriate Type and a file to be associated with drop down box on the top right side.
the representation, and click Apply. Two convenient options
can be selected during this step. 9. Once all representations are defined, click on the Assembly
·∙
A file assigned to the root representation can optionally Browser tab to review the assembly hierarchy with active
be auto-assigned to be a Display representation (PLOTFE Display and Analysis representations.
type) simultaneously by checking the Assign file to Display
representation checkbox.
·∙
A representation can be auto-selected to be the Display
representation by checking the Set as Display, load and
extract TagPoints checkbox. This will be followed by the file
being imported into the 3-D graphics window and TagPoints
defined in the file extracted.
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Step 6: Import Display Representations

1. From the Base View of the Assembly Browser, select the root Module Model.

2. Right-click and select Import DisplayRep > Recursive Modules to recursively load the active Display models.
Module representation include files specified as the display representation are loaded here.

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Step 7: Manage TagPoints
1. To manage tagpoints, open the TagPoint tab of any module by 2. To add a tagpoint, right-click inside the tagpoint list box, and
right-clicking on the module in the Assembly Browser and then select Extract to extract TagPoints from the comments added to the
select Manage Module > TagPoints. 10th field of the grids in the loaded Display model.

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Tagpoints displayed in the 3-D graphics area can be customized via Step 8: Prepare a Module for Assembly
the TagPoint Display tool setting. By default, tagpoints are
indicated with a grey sphere along with the label. Other options are In the previous two steps, you have assumed that the representation
available using the pull-down menu. file is already in an FE entity ID range that would not cause conflicts
with other modules in the assembly, and all necessary tagpoints
already exist in the file as 10th field comments on the respective grid
cards. However, these assumptions are not met in most practical
applications. Necessary preparation work needs to be done to get the
module representation files to a state that is ready for assembly. This
section describes how to accomplish this task.
1. To start the process of preparing a module, right-click on the
module and select Prepare Module to enter into the Prepare Module
Mode.

3. Repeat the extraction process to complete tagpoint definitions
of all modules.

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In the Prepare Module Mode the HyperMesh database is first
cleared to remove any potentially conflicting FE entities, and then
the root representation file is loaded into HyperMesh. A module ID
summary is then presented with all necessary information needed
for you to determine if the IDs need to be renumbered, and what
range they should be renumbered to.

This dialog shown below comes up as a part of the Prepare Module
action. It is split into two sections. The bottom section describes the
finite element entity ID in the imported FE file. The top section
provides a way to renumber the IDs, if necessary, into a range that is
not in conflict with other modules in the assembly. The Proposed
range is what the dialog has identified as one conflict free range,
which can be modified based on options to the right. Action is a
user specified operation to organize IDs into the Proposed range.

Once an appropriate ID management action has been applied, NVH
Director enters the Prepare Module Mode, and a Prepare Module tab
opens up in the browser area with sub-tabs designed to help you
perform many functions, such as:
·∙
Add spider: Help add spiders to a round hole. Select a type,
dofs, pick center (RBE3 only) and edge nodes, and then click
Create.
·∙
Edit systems: Help relocate or orient the module by modifying
the reference local coordinate system. This takes you directly
to the HyperMesh Systems panel to edit existing systems.
·∙
Orient and position: Help translate and rotate FE entities.
Input values in the appropriate input boxes and push one of the
buttons below to perform the function.
·∙
Assign damping: Help fill GE field of MAT1 cards. Enter a
damping value in the input box and click All or Select to apply
the damping values to all or selected material cards.

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In addition, a number of functionalities on the TagPoints tab
of the Module Manager, such as Add, Assign and Generate
PLOTEL elements, are enabled for you to manually add
tagpoints and assign them to grids in the module

2. Once you are finished preparing the module, you can prepare
another one from the Assembly Browser, or select to exit the Prepare
Module Mode by clicking on the X button on the Prepare Module tab.

A tagpoint mapping tool is also available in the Prepare
Module tab via the icon.

The mapping tool is able to reconcile in bulk the current
tagpoint definition in the assembly database with what
is in the root module file. You can also create new
tagpoints by reading a .csv file that contains hard point
coordinate and label information.

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You will be prompted with four representation file save options with 3. Once all of the modules have been prepared, you can review the
information on ID renumbering. Yes: The root representation file is assembly ID ranges and conflict setting from the Id View of the Assembly
to be saved, in this case, intra and inter ID conflict flag will be set to Browser.
Yes. No: The root representation file is not to be saved, in this
case, intra and inter ID conflict flag will be set to No. Cancel: The
exit Prepare Module Mode action is aborted. No, but VALIDATE:
In this case there is no change to the file and no need to save the
file, but intra and inter ID conflict flag will be set to yes.

At the individual module level, the ID tab of the Module Manager will
also be populated.

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Step 9: Define Connections Between Modules 4. To review the connections that were created, select Connector
Browser from the View pull-down menu.
1. From the toolbar, click on the icon to launch the
connection Interactive Create panel.

2. Connections can be created between modules to be
connected either by selecting tagpoints from the list box in the
panel, or by picking tagpoints. Hint: Pick and drag on the left
hand side of the tags to ease selection off the screen after
clicking on the Select TagPoints icon
.
You can also provide a description for the connector created,
specify an owning module, a local coordinate system, connector
location for the center of motion, and a collector for the connector
created.

3. Connections can also be created using the Auto Create
panel, which can be invoked by clicking on the icon. Two
automated creation approaches are available: auto creation by
Proximity or by Tagpoint Matching.

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The Connector Browser is divided into two browser panes. The top Owning module: This column indicates which module owns the
pane is the Module Pane, where connected modules are listed. You particular connection. The owning module is always the module on
can view connections attaching to modules using typical browser the PointA side of the connection. The connection definition and
functions, such as Show/Hide/Isolate. The lower pane is the properties always travel with or organized under their owning
Connector Pane, where individual connections are listed. Three modules when sub .xml files are written.
connection views are available from the Connector Pane.
·∙
Connectivity View: Columns in this view focus on Distance: This column shows the distance between PointA and
connectivity related details. Of particular importance are the PointB. It can be used as a metric for checking the validity of the
following columns: connection. Connections spanning large distances are potentially
connected by mistake. Some NVH engineers prefer to keep all
connections at zero length due to fear that non-zero length springs
may introduce unintended dynamic motion, which is a valid
concern if celas type spring elements are used during connector
realization. When cbush type spring and rbe2 type rigid elements
are used, this is the case for all current NVH Director supported
realization types, correct dynamic motion is ensured by element
formulation, and there is no longer a need to maintain zero
connection length.

Switch nodes: This column shows if there is a need to switch the
order by which PointA and PointB are used in generating rbe2 rigid
elements during connector realization. This need is driven solely by
dependency considerations of the connected points, since a point
that is already dependent cannot be made the dependent point
PointA/PointB: These two columns show the two tagpoints on two again in the connection element definition. Four possible states of
modules that are being connected for each connection. The same this column are possible. No: If PointA is independent, regardless
order (PointA first and PointB second) is used when generating of the dependency of PointB. Yes: If PointA is dependent, but
connection FE entities during connector realization. PointA/PointB PointB is independent, in which case PointB will be made the
may be shown with two incomplete status indications (in square independent point in realizations involving rbe2. Unresolvable:
brackets): [N/A] indicates that the tagpoint exists in the assembly This happens when both PointA and PointB are already dependent,
database, but is not available in the HyperMesh session (not in which case a realization involving rbe2 is not possible, and the
imported.) [Undefined] indicates that the tagpoint does not exist in connection will fail to realize. Unknown: If PointA’s dependency
the current assembly database, which means the tagpoint is either status is unknown or if PointA is dependent and PointB’s
deleted or the sub .xml file it travels with is not imported in the dependency status is unknown.
session.

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5. To review un-attached Modules, go to the Assembly Browser
Property View: Columns in this view focus on connection property types
and select Find Un-attached Modules. This action removes all
defined, local coordinate systems used and property set that is active.
modules attached by connections and provides a good way check if
all components shown in the 3-D graphics window are intentionally
un-attached.

Location View: Columns in this view focus on the location
definition.
6. Similarly, select Find Un-attached TagPoints to see if some
TagPoints are un-attached by accident.

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Step 10: Define Connection Information and Properties

1. Connection properties can be defined by first selecting a connector, 2. Click on the Update button to save the changes.
right-click, and select Manage Connection. A connection location type can be defined by selecting one of the
options from the pull-down menu: Point A, Point B, Midpoint, or a
CustomLocation. When CustomLocation is selected, the location
can be defined either by specifying a specific coordinate, or by
mapping it to a Hardpoint location.

This opens the General tab of the Connection Manager, where
you can edit the connector’s general information including
Label, Description and Owning Module.

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3. Click on the Update button to save the changes.
Information related to Connected Points, and distance between
them, is displayed in the next section. You can modify any
connecting tagpoint by clicking on the icon next to its label, which
brings up the Tagpoint Selection tool. You can then select a module
first in the Module pull-down list, select a tagpoint owned by the
module, or click on the icon and pick a tagpoint on the screen
in the 3D graphics window, and then click Select. The tagpoint list
can be further filtered by clicking on the icon and selecting one
of the tagpoint types: Response, Connection, Input, Plot, or All
(default).

The first step in defining connection properties is to select a
When checked, the Switch Nodes check box allows you to change State Set. State Set is designed to capture a unique hardware
the independent node from Point A to Point B, based on their part with its own set of connection properties. For example,
dependency status, to avoid an already dependent node being hydromount vs. a base rubber part. By default, a base State Set
specified as dependent again when the connection is realized into is already created and assigned to the connector. Therefore,
new rigid elements. Connection properties are defined in the State unless there is a need for multiple sets of properties, the default
tab of the Connection Manager. base State Set selection does not need to be changed.

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4. To select another State Set click on the Edit... button. This opens
the Select State Set dialog.

As seen in the screenshot above, five options are available in
State Sets can be added by clicking on the icon, or deleted by specifying coordinate systems used by any CBUSH element
clicking on the generated during connection realization:
icon. You can double click on a State Set to edit its
·∙
Vehicle – ‘0’ or the basic coordinate system is used.
name, and click on the Select button to finalize the selection.
·∙
Owned – This option allows you to create a custom LCS
by clicking on the Edit… button.
The second step in defining connection properties is to select a LCS
·∙
TagPointA – Local coordinate system specified as the
(local coordinate system) for the properties to be defined in the next
output Displacement Coordinate System on the grid
step.
card associated when TagPointA is used.
·∙
TagPointB – Local coordinate system specified as the
output Displacement Coordinate System on the grid
card associated when TagPointB is used.

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When the Owned local coordinate system is selected, a local
coordinate system managed in the assembly can be created Angle – Any combinations of angle rotations around the reference
using the Define Local Coordinate System dialog. Three types axes can be used to define this system.
of coordinate systems can be defined:

Axis-Plane – Two vectors are required to define this system. A
vector can either be specified in direction cosines, or by selecting
two tagpoints.

Ujoint – The Ujoint coordinate systems is defined by selecting two
tagpoints on the input shaft and two tagpoints on the output shaft.
A homo-kenetic coordinate system will then be created to properly
describe motion transfer of Ujoints from the input to the output
shafts.

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The last step in defining connection properties is to define property As seen in the screenshot above, five options are available in specifying
states. property states:

PBUSH – A CBUSH element is generated during connection realization.
The PBUSH card allows you to specify K (stiffness), B (viscous
damping), GE (material damping), M (mass and moment of Inertia), and
RIGID (check boxes for rigidly connected dofs.) Note: The M and RIGID
fields are not supported in the Nastran profile, and are ignored.

RIGID – A RBE2 element with dofs specified in checked boxes is
generated during connection realization.

PBUSHT – A CBUSH element is generated during connection
realization. In addition to the PBUSH card that specifies the base
properties, a PBUSHT card allows you to specify frequency tables for K,
B, and GE.

PBUSH-MASS – A CBUSH element with two COMN2 elements at its
Point A and Point B are generated during connection realization. Note:
This type is designed to be used in the Nastran profile where the M
fields for PBUSH are not supported by the Nastran solver.

PBUSH-RIGID – A CBUSH element with a parallel RBE2 element are
generated during connection realization. Note: This type is designed to
be used in the Nastran profile where the RIGID check boxes for PBUSH
are not supported by the Nastran solver.

- 78



5. Click Apply to save each property state definition.
Property states can also be imported using the Import from File
option by clicking on the icon. This opens the Import States
dialog.

6.  Browse and select a connection property template file, select a
connection property set, and click on Import to load the property
states.

7. Repeat the above process for all connections to complete property
definition.

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NVH Director Feature – Tutorial

Step 11: Manage Analysis
An Analysis is a collection of module and connection selection that
completely specifies the assembly definition for a particular simulation
event. The Analysis Manager is invoked from the Connector
Browser by clicking on the icon.

1. To add an analysis by extracting active module and connection
settings, click on the icon. To add an analysis by copying module
and connection settings from the selected analysis, click on the
icon. To add a blank analysis, click on the icon.

2. To delete an analysis, first check the radio button corresponding
to the analysis and then click on the icon next to the name of
the analysis.

The top section of the Analysis Manager is used to define
analyses, which is further divided into three parts. The first is for
module representation and state selection, the second is for
connection state selection, and the third is for template loadcase
definition.

3. To define module representations, select the representation via
the list individually, or globally all representations by type via the
right-click context menu, shown on this page.

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NVH Director Feature – Tutorial

4. To define connection state, pick a State label, such as idle or WOT. 6. Highlight an existing definition or add a new one by clicking on the
icon to open the NVH Loadcase Templates dialog.
5. To define template loadcase, click on the ‘…’ icon to invoke the
Select Loadcase Definition dialog.

The next section of the Analysis Manager is used to apply the
module representation and state selections to the ones and realize
connections to states defined in the selected analysis.

7. Once an analysis has been applied, the Export solver deck
section is enabled. Click on the Export icon to save a solver deck
to submit to the targeted solver for analysis.

All analysis information is saved in the assembly XML file, and
retrieved when the file is loaded back.

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Loadcase Setup

- 82


LOADCASE TOOLS

•  The loadcase setup framework
•  Process manager to gather user input and generate solver cards

•  3D display for entity selections as a part of the user input

•  Optionally, loadstep browser can be used to review and customize generated solver cards

•  Loadcase setup process managers have been developed for
•  Normal modes

•  CMS SE generation

•  Unit input frequency response

•  Random PSD frequency response

•  General frequency response

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Benefits of PM Approach

§  Processes can be automated and set up to define ‘best practice’

§  Loadcase setup follows a step by step process

§  Simple and fast way to generate complex decks

§  3D display for entity selections as a part of the user input (easier to set up than Deck
number editing)

§  Solver cards can be reviewed and edited through the loadstep browser

§  Bespoke process managers can be developed on request

- 84


Unit Input Frequency Response - Tutorial
In this exercise we will use the Process Manager to generate a dynamic stiffness FRF

Step 1: Start Process Manager
1. Open Tools – Freq Resp Process – Unit input frequency response

- 85



Step 2: Select Solution Type

In this step, pick either the Direct Frequency Response solution method, or the Modal
Frequency Response solution method. For large problems involving more than a few
frequencies, the modal solution is typically the most efficient solution.

Step 3: Select Analysis Frequencies

In this task, enter the frequencies for which the response solution is
needed. Choose one of three ways to define the frequency set:
1. Min., Max, and a linear step
2. Min., Max, and a number of increments with logarithmic
spacing
3. An arbitrary list of frequencies
For options 1 and 2, select the Frequency range radio button and
an Increment type (Linear or Logarithmic), and fill in the required
fields. For option three, simply type in a list of arbitrary frequencies,
then click on Update. A frequency set entry is created in the list box A typical setting would be 10 to 300Hz at increments of 1Hz
to the left.
Once the frequency set(s) has been defined, click on Apply to Note additional FREQ cards can be added after the end of the PM if
proceed to the next task. more advanced settings are required.

- 86



Step 4: Normal Mode Extraction

This step sets up the EIGRL cards.

Typical range would be 1.5 to 2* higher than FRF range
required.

*Include Fluid mode extraction if NTFs are required.

Step 5: Define Loads / Inputs

Define the load type, Force in this case The DOFs need to be ticked depending on which input directions you
want. Right click to define all translational or all directions more
Then select entity quickly.
If Tag points exist then these can be used to AutoAdd selection
Nodes and Nodes sets can also be used

- 87



Step 6: input Transfer Function Requests

This step lets you select to output transfer function between
input points.

Drive Point enables you to generate responses automatically
from the input points. This is required to Dynamic Stiffness

Step 7: Add Response Points

This step enables you to add additional response points that are required for FRFs such as NTFs and VTFs

In the case of Dynamic Stiffness we do not need to define any additional points.

For NTFs, pressure is not currently available as a response option so create the response as displacement in X and then
convert to a pressure response after the process manager has been completed.

- 88



Step 8: Miscellaneous Options
This step enables you to apply damping
and define coupling requirements for
NTFs.

Step 8 and 9: SPC and MPC Selection

In this case we do not need to define SPCs or MPCs

Step 10: Parameter Selection
This steps adds the parameters and heading to the deck

Select YES to close the template when the process is complete

- 89


Step 11: Export Deck

All created entities can be viewed/edited in the Model browser

Any changes can then be made before the DECK is then exported using standard DECK
export.

- 90


Full Vehicle NVH Optimization

- 91


Vehicle design optimization approach

Run vehicle simulation
Identify problem loadcase and responses
Identify key areas to optimize
§  Perform diagnostic analysis
§  Conduct what-if studies
§  Identify key component/panel and design
variables
§  Keep ‘design’ area as detailed FE mesh
Reduce non-design parts of the vehicle
§  Reduce to CMS Super Elements
•  Combined Fluid-Structural SE
•  Acoustic Cavity is included in the SE
§  Export of reduced matrices
•  Stiffness
•  Mass
•  Structural damping and viscous damping
§  DMIG input and output
Optimize design variables
§  Size, shape, topology, topography
§  Mastic or Beads on panels
§  Weight

- 92


Exterior noise optimization example

Model
-  A 1.0 meter hollow cube with 9 different plate components.
-  The wall thickness were initially set to 1 mm
Surface velocity to exterior response coupling
-  Coupling from all the points on the cube to 6 exterior acoustic
response points
-  Data was provided by HW Partner Ansol using a Multipole
BEM solver called Coustyx
DESVAR cards were created to optimize
-  9 plate thickness(1 mm),
-  9 structural damping (.001) Exterior Acoustic Optimization

3.00E-08
-  9 non structural mass (1.0E-10)

Result
GRID 1
GRID 2

Acoustic Response
2.00E-08 GRID 3
GRID 4

1.  Radioss optimized the response points in 5 iterations
GRID 5
GRID 6
GRID 1 OPT
GRID 2 OPT

2.  The main changes were in the plate thickness and the 1.00E-08
GRID 3 OPT
GRID 4 OPT
GRID 5 OPT

structural damping values
GRID 6 OPT

0.00E+00
200 250 300 350 400 450
Frequency

- 93


Recap and Summary


Most advanced true full-vehicle NVH solution

1.  Integrated process leading to massive efficiency
gains in executing tasks in a full-vehicle process
•  Interface with PLM system for data exchange
•  Facilitate subsystem meshing and assembly related operations
•  Manage NVH event simulation loadcases, analysis, and job
history
•  Leverage model and assembly data for post-processing
•  Integrated NVH problem diagnostics and optimization
•  Enable a multiple discipline modeling and optimization
framework
•  Allow few engineers to support an entire vehicle platform

2.  Modularized subsystem handling enabled by an
object-oriented environment
•  Switch between detailed and reduced representations and
setup runs with mixed representations
•  Manipulate visual display in 3D graphics window
•  Manage ID conflicts within the assembly
•  Ability to store subsystem assembly data in nested xml files


Most advanced true full-vehicle NVH solution
3.  Specialized modeling and solution features to
reduce complexities in full vehicle simulation
•  Lumped parameter model and complex mounts and joints
needed for simulating suspension and driveline
•  Acoustic cavity mesh for fluid structure interaction analysis,
and coarse display mesh for simplified 3D display
•  AMSES eigen solver, PEAKOUT peak filtering, CMS and
CDS SE dynamic reduction , and enhanced bushing element
4.  Innovative NVH problem diagnostic and study
capabilities
•  Modal animation, operating response shape (ODS)
•  Modal/panel/grid participation from both system and CMS SE
component modes
•  Transfer path analysis and powerflow
5.  Enhanced user experience by leveraging latest
technologies
•  Browser, connector, data manager, process manager etc


In Summary

Key points
More information

•  NVH Director has integrated •  NVH pages on HyperWorks
functionalities that can
Website
drastically improve efficiency
and productivity
•  NVH Director documentation
•  NVH Director has a strong under Engineering Solutions
emphasis on helping CAE •  In-depth NVH training class –
engineers to make a real impact
contact your account
on product development
manager
•  NVH Director is based on many
decades of practical experience
in true full vehicle simulation

Altair HTC 2012 NVH Training

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