Working with Femap
Free bodies and Global / Local
Modeling
Femap Symposium Series 2015
Unrestricted © Siemens AG 2015
Siemens PLM UK Symposium
Femap Track Agenda
11:00:
Femap – introduction and what’s new
11:50:
Working with Femap – free bodies and global / local modeling
13:30:
Femap industry customer case studies:
Aerospace & marine
Customer presentation
Longitude Consulting Engineers (London Offshore Consulting)
Your presenters today:
Nick Rakkar
Al Robertson
Joe Brackin
Peter Kingsland
Page 2
UK Channel Sales Manager, Siemens PLM Software
Product Marketing Manager, Siemens PLM Software
Senior Software Engineer, Siemens PLM Software
Naval Architect, Longitude Consulting Engineers
Siemens PLM Software
Siemens PLM UK Symposium
Femap Track Agenda
15:40:
•
•
•
•
Event wrap up
We will be available for questions and discussion after the event
Femap futures and roadmap
Femap technical queries
How can Femap help in your business
Who can you talk to regarding software solution testing
Nick Rakkar – UK Channel Sales Manager
Nick.Rakkar@siemens.com
07837 553 633
Page 3
Siemens PLM Software
FEMAP Freebody Deep Dive
Topics
•
•
•
•
•
•
•
•
What is a Freebody?
Recovering Grid Point Forces in NASTRAN
Understanding Grid Point Force Output
Freebodies in FEMAP
Using the FEMAP Freebody Toolbox
FEMAP Freebody Options
Global / Local Modelling with Freebodies
Additional Topics
Page 4
Siemens PLM Software
What is a Freebody?
Freebody Displays provide an insight into the internal forces and moments
of the FEM
• In FEMAP, Freebody display can
be used to display a balanced set
of loads on a portion of the structure
or calculate the load across an
interface
• Freebody displays are commonly
used when modeling practices dictate that the resulting FE mesh is a “coarse-grid” mesh
but is suitable as an “internal loads” model
• Commonly modeled structures are often too complicated to model in sufficient detail
to obtain directly useable stresses
• Allows for forces / moments to be extracted for detail stress analysis
• Freebody displays are heavily used (but not limited to) in the aerospace industry
Page 5
Siemens PLM Software
Freebody Display Requires Recovering Grid Point
Forces in NASTRAN
Turning on the NASTRAN GPFORCE
case control request is required to
take full advantage of the FEMAP
Freebody Tool
• Enabling GPFORCE Output in NASTRAN Case Control
• Analysis Manager
• Master Requests and Conditions
• Output Requests
• Force Balance
• GPFORCE requests can return a large
amount of data, so this option
is not enabled by default
Page 6
Siemens PLM Software
Freebody Display Requires Recovering Grid Point
Forces in NASTRAN
• FEMAP can work with a reduced set
of data including applied load (OLOAD),
constraint force (SPCFORCE), and
constraint equation (MPCFORCE)
• This is generally not recommended
unless only a generic freebody
display of the entire structure is
all that’s required.
• Care should be taken when
not requesting GPFORCE data for
the entire model.
Page 7
Siemens PLM Software
Understanding Grid Point Force Output
NASTRAN F06 Output
• When the results destination is set to “Print Only” or “Print and PostProcess”
GPFORCE data can be viewed in the F06 file
• Note that it is still recommended to read GPFORCE data into FEMAP from
the OP2 file, not the F06 file
• Search for “G R I D P O I N T F O R C E B A L A N C E”
G R I D
POINT-ID
0
0
Page 8
ELEMENT-ID
1
1
1
1
2
2
2
2
2
3
3
3
3
3
267
268
267
268
269
270
269
270
271
272
SOURCE
F-OF-SPC
QUAD4
QUAD4
*TOTALS*
QUAD4
QUAD4
QUAD4
QUAD4
*TOTALS*
QUAD4
QUAD4
QUAD4
QUAD4
*TOTALS*
P O I N T
T1
4.169596E-02
1.213303E-01
-1.630262E-01
9.436896E-16
-7.904667E-01
-3.752280E-01
5.058178E-01
6.598768E-01
-1.798561E-14
-2.833224E-01
-2.021358E-01
1.617432E-01
3.237150E-01
1.049161E-14
F O R C E
T2
1.031393E+00
5.287078E+00
-6.318471E+00
-6.306067E-14
-1.515594E+02
-1.348000E+02
1.277458E+02
1.586136E+02
-1.136868E-12
-7.450614E+01
-4.297056E+01
5.205509E+01
6.542161E+01
8.540724E-12
B A L A N C E
T3
-5.078434E+01
-1.944031E+01
7.022465E+01
2.557954E-13
3.756228E+02
-4.464662E+02
2.504629E+00
6.833877E+01
7.389644E-13
3.083269E+02
-3.489907E+02
-2.303685E+01
6.370063E+01
-2.700062E-13
R1
0.0
2.078351E-03
-2.078351E-03
1.934217E-16
1.975718E-01
1.780457E-01
-1.799477E-01
-1.956698E-01
6.383782E-16
1.501767E-01
1.569770E-01
-1.572558E-01
-1.498980E-01
1.665335E-16
R2
0.0
5.017486E-01
-5.017486E-01
0.0
5.075642E-01
-5.262242E-01
-1.129834E-01
1.316434E-01
1.493250E-14
-1.241496E-01
1.129076E-01
-2.788103E-01
2.900524E-01
-2.886580E-15
R3
0.0
4.834255E-04
-4.834255E-04
-2.333203E-16
1.493221E-02
2.671471E-02
-4.392642E-02
2.279495E-03
5.551115E-17
2.011796E-02
4.146868E-02
-1.574009E-02
-4.584655E-02
8.326673E-17
Siemens PLM Software
Understanding Grid Point Force Output
NASTRAN F06 Output
• GPFORCE results are listed per grid and include Fxyz (T1, T2, T3) and Mxyz
(R1, R2, R3)
• Results are separated into 4 different categories, plus a summation
• Elemental (discrete; per connecting flexible element)
• Applied Load(total forces / moments applied on node; single quantity per
node)
• F-of-SPC (SPC forces on node; single quantity per node)
• F-of-MPC (MPC forces on node, including both constraint equations and
RBE contributions; single quantity per node)
• *TOTALS* (total summation of all contributions; single quantity per node)
• For the majority of cases, this value should be near zero, indicating
equilibrium at the node
Page 9
Siemens PLM Software
Understanding Grid Point Force Output
How GPFO Relates to Structure
• Freebody display is dependent on the nodes and elements included in the
summation
• Deciding which nodes and elements are to be used is based on how the
model was idealized as well as what specific quantity is desired
Page 10
Siemens PLM Software
Freebody Display in FEMAP
Freebodies in FEMAP exist as creatable objects, like nodes, elements, etc.
• They persist in the database
• This is a huge benefit for recreating freebody displays in the future
• Can help reduce analysis errors and rework
• Any number of freebodies can be displayed simultaneously
• Many tools exist to automate freebody-related tasks, such as creating loads
and substructure modeling
Page 11
Siemens PLM Software
Freebody Display in FEMAP
FEMAP Freebody Types – There are 3 types of freebody displays in FEMAP
• Freebody – user selects the elements, FEMAP automatically selects related
nodes. Intended to display a balanced set of loads on a discrete piece of
structure
Page 12
Siemens PLM Software
Freebody Display in FEMAP
FEMAP Freebody Types – There are 3 types of freebody displays in FEMAP
• Interface Load – user selects both nodes and elements and FEMAP
calculates a summation of loads and forces across the interface and displays
as a single vector
Page 13
Siemens PLM Software
Freebody Display in FEMAP
FEMAP Freebody Types – There are 3 types of freebody displays in FEMAP
• Section Cut – similar to interface load, a summed load across an interface is
calculated and displayed, however node and element selection is automated
by FEMAP. The user selects a “cutting plane”. The cutting plane can then be
dynamically located within the model using different methods.
Page 14
Siemens PLM Software
Freebody Display in FEMAP
Freebody Load Contributions
• Freebody load contributions in FEMAP are split into six categories
• Applied – All applied loads
• Reaction – SPC forces(Constraint forces)
• MultiPoint Reaction –
MPC(MultiPoint Constraint forces)
• Peripheral Elements – include elements
surrounding the selected elements
• Freebody Elements – include elements
selected by the user or by FEMAP
• Nodal Summation – nodal summation values
from the solver, not FEMAP calculated values
• Default contributions are Applied, Reaction, MultiPoint Reaction and
Peripheral elements
• This provides forces and moments acting on the selected structure
Page 15
Siemens PLM Software
Freebody Display in FEMAP
Freebody Result Vectors – As previously mentioned, the NASTRAN GPFORCE
request is recommended to fully take advantage of the freebody tool, however
the result quantities may be obtained from several different quantities
Primary
Secondary
Applied
GPFORCE
OLOAD
SPC
GPFORCE
SPCFORCE
MPC
GPFORCE
MPCFORCE
Elemental
GPFORCE
None
Nodal Summation GPFORCE
None
The italicized rows above represent default output requests in FEMAP and are
sufficient for displaying a balanced freebody on the entire structure, but not for
display of internal load distribution.
Page 16
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Accessing the Freebody Toolbox
• The Freebody Toolbox is located in the
PostProcessing toolbox and can only
be accessed when results are present in
the model
Global Settings – These controls affect all
freebodies in the model. Control global display
of freebodies, select output set (tied to contour
and deform) and enable data summation on
nodes
Freebody Properties – These controls are
related to individual freebodies, such as
selecting nodes and elements
View Properties – These are global settings
that affect freebody visualization (symbol sizes,
vector scaling, etc). Same as found in View
Options (F6)
Page 17
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Creating a New Freebody
• In the Freebody Toolbox, new Freebody Displays are created within the
Freebody Manager
• The New Freebody dialog allows for setup of basic settings, such as freebody
type, vector display, and contribution selection
• Any of the settings applied in the New Freebody dialog can be changed at any
time within the toolbox
Page 18
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Accessing Different Freebody Displays
• Multiple Freebody Displays can be viewed at any
time however, only a single freebody can be
active at any time within the toolbox
• Use the drop-down menu to change the active
freebody and then modify settings
• Visibility of individual freebody displays can be
controlled with the “Is Visible” checkbox as
well as with the Visibility Quick View Dialog
Page 19
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Freebody Vector Types
• Depending on the freebody type, there can be nodal vectors and a single total
summation vector
• Nodal Vectors
• Displays the summation at each node, based on the selected freebody
contributions
• Available for all freebody types
• Total Summation Vector
• Displays the total summation across all nodes at a pre-defined position.
The selected position does not affect summed force calculations, but will
affect summed moment calculations (moment arms are different).
• Available for Interface Load and Section Cut freebodies only.
• Both force and moment vectors are available and can be individually toggled
• Vectors can be displayed as either components or resultant vectors
• Individual components can be toggled on and off
Page 20
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Freebody Vector Visualization
Visibility Quick Toggle Buttons
• All On / All Off
• Forces On/Off
• Moments On/Off
• Toggle between resultant/component
• Select summation location (interface load
and section cut only)
Page 21
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Freebody Vector Visualization
Detail Options
• Additional detailed options for visualization
can be found by expanding the Total
Summation Vector and Nodal Vector(s)
nodes
• Select components displayed (Fx, Fy, Fz),
(Mx, My, Mz)
• Select components included in calculation
(interface load and section cut only)
Page 22
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Freebody Coordinate Systems
• The selected freebody coordinate system
controls the coordinate system for both nodal
vectors and the total summation vector (if
applicable) for the selected freebody
• Nodal vectors may optionally be displayed in
the nodal output coordinate system
• If no nodal output system was specified on
the node, the default coordinate system used
is the global rectangular system
Page 23
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Freebody Mode
• When using “Freebody Mode”, the user selects
elements and FEMAP will automatically select
all related nodes
• This mode is designed to display a balanced
set of loads on a selected set of elements
• Entities may be selected manually (default) or
by a group select
• The default contribution selections will display
forces/moments acting on the selected
elements
Select Elements
Reset Element Selection
Highlight Selected Elements
Page 24
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Display of balanced set of loads on wingpost model. All elements in the model
were selected for this display
Page 25
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Interface Load Mode
• Interface load freebodies display nodal
vectors for the selected nodes as well as a
total summation vector at a selected location
• Unlike freebody mode, interface load mode is
not likely to be in equilibrium
• In addition to element selection, nodes must
be user selected– FEMAP does not infer
them based on the selected elements
• When selecting entities by group, both the
nodes and elements of interest must exist in
the group
Page 26
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Interface Load Mode – Selecting Nodes
Locate Summation Vector at Node Centroid Select Free Edge Nodes
Select Nodes
Reset Node Selection
Highlight Selected Nodes
Only those elements connected to the
selected nodes will be used in calculations
Page 27
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Interface Load Mode – Selecting Components in Summation
• Individual force and moment contributions
that are included in the total summation
vector calculation toggled on and off
• By default, all force and all moment vectors
are included in the calculation
• Changes made here will affect the total
summation calculation
• Turning on and off certain contributions
is dependent on how the model was
idealized ; it is up to the analyst to
understand how the FE model correlates
to real-world structure
Page 28
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Interface Load Display, Showing Summed Shear Load at a Rib
Selected Nodes Highlighted
Selected Elements Highlighted
Page 29
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Section Cut Mode
• An extension to Interface Load Mode
• The user defines a cutting plane in the
model and the contributing freebody
nodes and elements are determined
automatically
• Total summation location can be placed at
• Plane/path intersection
• Nodal centroid
• Static location
• Nodal and total summation vectors can
optionally be aligned tangent to the path
without having to create additional
coordinate systems
Page 30
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Freebody Section Cut
Entity Select Modes
Plane: Cutting plane is defined via base
point and normal vector. Path is defined as
the normal vector; cutting plane will always
be normal to the path
Curve: Cutting plane is normal to the
tangent vector at a point along the plane.
Cutting plane will always be normal to the
tangent vector
Plane / Vector: Similar to Plane, however
an additional vector is defined for the path.
The cutting plane will always remain coplanar to the original plane and does not
have to be normal to the path
Vector: Cutting plane is normal to the
defined vector. Path is the defined vector;
cutting plane will always be normal to the
path
Page 31
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Section cut defined using plane
Page 32
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Section cut defined using curve
Page 33
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Additional Section Cut options
• Slider tool can be used to move the cutting
plane along the length of the path
interactively within the available entities
• Section cut entities may be limited to a
specific group or selected from the entire
model, and can be limited to a search
distance from the base location of the
cutting plane
• The cutting plane can optionally be given a
thickness tolerance that will allow for
accurate selection of entities that are
slightly out-of-plane
• Clipped entities can either be included or
excluded from the summation calculations
Page 34
Siemens PLM Software
Using the FEMAP Freebody Toolbox
Cut plane initial position
Cut plane moved along the path
Freebody nodes
Freebody elements
Page 35
Siemens PLM Software
Freebody Display Output Options
Freebody Tools
1
2
3 4 5
1 – List freebody to message window
2 – List freebody to data table
3 – List freebody summation to message
window (interface load / section cut)
4 – List freebody summation to data table
(interface load / section cut)
5 – Freebody validation tool; warns user
when freebody results are potentially
missing from the model
Page 36
Siemens PLM Software
Global-Local Modeling with Freebodies
The Create Load from Freebody/Multi-Model tool automates the creation of
global-local models
• Used to map freebody loads from a coarse grid model to a fine grid model and
automatically create connections with RBE3 elements
• Start with a balanced freebody in a coarse model
• FEMAP can automatically locate suitable
target nodes in the fine grid FEM and will
connect with RBE3 elements
• Once properly constrained, the detail FEM is
ready to run with a mapped set of loads
• The detail FEM must exist in the same
space as the part in the coarse grid FEM
Page 37
Siemens PLM Software
Global-Local Modeling with Freebodies
• Select Source Model
• Select Freebody
• Select Output Sets
• Multiple Sets allowed
• Select Forces and/or Moments
to be included
Page 38
Siemens PLM Software
Global-Local Modeling with Freebodies
Define Target Model Parameters
Freebody loads can be applied to target
nodes based on:
• Existing nodes (IDs must match)
• Closest node in space to source
node
• Existing nodes to be connected with
RBE3 elements
• User can define target nodes or
FEMAP can automatically find
• Search distance can be limited
• Maximum nodes to map can be
limited
Page 39
Siemens PLM Software
Global-Local Modeling with Freebodies
Source Model Freebody(Global Model)
Target Model with RBE3 Load Distribution
Page 40
Siemens PLM Software
Additional Topics –
Freebodies with NX Nastran Glue / Contact
As of NX Nastran v10.1, the GPFORCE output request does not include
contributions from glue or contact in the F06 or OP2 datablock
• The result is a nodal imbalance that is the summation of all other contributions
• Nodes that are affected by glue or contact will not be in equilibrium
• The “TOTALS” quantity is equal and opposite to the existing summation
G R I D
0
0
POINT-ID
686
686
686
686
686
686
686
686
686
10000
10000
ELEMENT-ID
821
822
827
828
857
858
863
864
468
SOURCE
HEXA
HEXA
HEXA
HEXA
HEXA
HEXA
HEXA
HEXA
*TOTALS*
HEXA
*TOTALS*
P O I N
T1
-7.854530E-03
-4.059431E-03
7.568718E-03
-2.503399E-02
-2.316282E-02
-1.751655E-03
3.478360E-03
5.081535E-02
-1.318390E-16
2.385245E-17
2.385245E-17
T
F O R C E
T2
5.974986E-02
4.661321E-02
-6.126883E-02
-9.182400E-02
4.661320E-02
6.132058E-02
-9.182400E-02
3.061997E-02
5.620504E-16
5.842150E-02
5.842150E-02
B A L A N C E
T3
7.854530E-03
2.316282E-02
-7.568719E-03
-3.478359E-03
4.059429E-03
1.751656E-03
2.503399E-02
-5.081535E-02
-4.440892E-16
3.122502E-17
3.122502E-17
R1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
R2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
R3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Glue/Contact Force balances the element
force, but is not included in table
Page 41
Siemens PLM Software
Additional Topics –
Freebodies with NX Nastran Glue / Contact
In FEMAP 11.2, the ability to reverse the nodal summation value was added,
allowing the nodal imbalance to be treated as a separate contribution in the
equal-and-opposite direction
• This option should only be used if the
cause of the imbalance is known to be
the result of data missing from the GPFO
table(glue/contact force) and not caused
by a modeling error.
Page 42
Siemens PLM Software
Additional Topics –
Freebodies with NX Nastran Glue / Contact
Page 43
Default contributions
Freebody elements / nodal summation
Freebody elements + nodal summation
Reversed nodal summation
Siemens PLM Software
Additional Topics –
Load from Freebody Tool
Freebody results can be used to create loads within an existing model using the
Model->Load->From Freebody tool
• Works with all freebody modes
• For interface load and section cut
freebodies, total summation load
can be created at a new node in
the model
• Loads can be created in an
existing load set as well as
in a new load set
Page 44
Siemens PLM Software
Additional Topics –
Load from Freebody Tool
Freebody Loads
Page 45
Siemens PLM Software
Additional Topics –
Load from Freebody Tool
Created Loads
Page 46
Siemens PLM Software
Additional Topics –
Sum Data on Nodes Option
By default, freebody vectors at each node are displayed as a summation of the
selected components
• A global setting allows for nodal
quantities to be displayed as
individual contributions. It affects
all displayed freebodies
• This allows for comparison of individual
contributions to F06 data, as well as
troubleshooting of models
• This option is best used with
the element shrink view option
Page 47
Siemens PLM Software
Additional Topics –
Sum Data on Nodes Option
Sum Data on node checked
Sum Data on node unchecked,
element shrink display
ID: 342
Source
Fx
Fy
Fz
Mx
My
Mz
ELEM 8
-4.12634 -2.76307 -130.752 46.32936
47.4351 -1.88713
ELEM 182
-18.5132
142.901 -466.199 0.280101 0.999626 0.022155
ELEM 80
208.315 34.15445 109.5391 0.067844 0.091289 -0.06195
Page 48
Siemens PLM Software
Q and A
Page 49
Siemens PLM Software
Siemens PLM UK Symposium
Femap Track Agenda
11:00:
Femap – introduction and what’s new
11:50:
Working with Femap – free bodies and global / local modeling
13:30:
Femap industry customer case studies:
Aerospace & marine
Customer presentation
Longitude Consulting Engineers (London Offshore Consulting)
Your presenters today:
Nick Rakkar
Al Robertson
Joe Brackin
Peter Kingsland
Page 50
UK Channel Sales Manager, Siemens PLM Software
Product Marketing Manager, Siemens PLM Software
Senior Software Engineer, Siemens PLM Software
Naval Architect, Longitude Consulting Engineers
Siemens PLM Software
Siemens PLM UK Symposium
Femap Track Agenda
15:40:
•
•
•
•
Event wrap up
We will be available for questions and discussion after the event
Femap futures and roadmap
Femap technical queries
How can Femap help in your business
Who can you talk to regarding software solution testing
Nick Rakkar – UK Channel Sales Manager
Nick.Rakkar@siemens.com
07837 553 633
Page 51
Siemens PLM Software