Question
Asked 7th Jan, 2014

What is modal neutral file and what is its' significance in Multibody dynamic analysis?

I would like to transfer transient analysis results from Finite Element Analysis Tool to MultiBody Dynamic Tool.

Most recent answer

30th Jul, 2020
Abbas Shafiee
Purdue University
Has anybody created MNF in ABAQUS? I have a quick question. Do I need to define boundary points for the frequency step or it is just needed for the substructure generation step?

All Answers (5)

7th Jan, 2014
Jochen Damerau
Schaeffler Japan
I guess that you mean the "Modal Neutral File"?
Actually this is a binary file format used by MSC Adams that contains the data of a flexible body. It can contain information like the invariants of the inertia matrix, the mode shapes and frequencies of the modal base derived from fixed boundary eigenmodes and constaint modes (through orthonormalization, Craig-Bampton modal synthesis) and the position of the chosen interface nodes and maybe other nodes (for graphical representation).
This data is obtained from a linear FE analysis (eigenmode analysis, substructuring) and the major commercially available FE-solvers can write this file ready for import in Adams.
The 'reduced' modal representation of the deformable body contains much less degrees of freedom than the original nodal representation as tze higher frequency modes are usually truncated.
To 'transfer' a transient analysis, you might have to build an analog model to the FE-model in MBS-software and apply the same time dependent loads at the same interface nodes. If you get similar results will mostly depend on a proper choice of the modal basis.
1 Recommendation
26th May, 2020
Suguang Dou
Technical University of Denmark
Not an answer, but a related question. How to read the Modal Neutral File outside the MBS software? Are there open-source codes to read this kind of binary file? Just curious.
26th May, 2020
Cristian Enrico Capalbo
Università della Calabria
I am also looking for tools to read a .mnf file, I need to import inertial invariants on Matlab. Does anyone know how to do it?

Similar questions and discussions

I am getting static equillibrium error while running full vehicle simulation? How to avoid that??
Question
2 answers
  • Nikhil P BNikhil P B
Reading in property files...
Reading of property files completed.
Setting up the vehicle assembly for Driving Machine maneuver...
Setup of vehicle assembly completed.
Simulation is beginning...
Starting analysis #1 of vehicle assembly...
-------------------------------------------------------------------------------
| .. .. |
| ####*. ####. |
| `###*. `#. MSC Software |
| `###. #. ------------ |
| `##. ## |
| `##. ## |
| `## ##' A d a m s C++ S o l v e r |
| #### Build: 2019.0.0-CL639814 |
| ###. Version: Adams 2019 |
| ###`#. |
| .### `# |
| #### `# |
| #### #. |
| .##### |
| #####' |
| #### |
| |
| ********************************************************************* |
| * * |
| * MSC Software Corporation * |
| * * |
| * A d a m s * |
| * * |
| * Automatic Dynamic Analysis of Mechanical Systems * |
| * * |
| ********************************************************************* |
| * * |
| * LEGAL INFORMATION * |
| * * |
| * Warning: This computer program is protected by copyright law * |
| * and international treaties. Unauthorized reproduction or * |
| * distribution of this computer program, or any portion of it, * |
| * may result in severe civil and criminal penalties. * |
| * * |
| * Copyright (C) 2019 MSC Software Corporation and its licensors. * |
| * All rights reserved. * |
| * * |
| ********************************************************************* |
| |
|-----------------------------------------------------------------------------|
| |
| ********************************************************************* |
| * * |
| * Local Time: 2020-02-19 19:50:20 * |
| * Host Name: NIKHIL-PC * |
| * Uname: MS Windows NT * |
| * OS Info: 6.2 * |
| * User: NIKHIL * |
| * Customer ID: D97DF9EF-3221A28B * |
| * Current dir: C:\Users\NIKHIL * |
| * Process ID: 10700 * |
| * * |
| ********************************************************************* |
| |
-------------------------------------------------------------------------------
OS-environment variable
MSC_USE_FORTRAN_STYLE_RELOAD_MESSAGE_FILE=1
Asol SDK. Enforces Adams Solver (C++) to use the Adams Solver (FORTRAN) message file style when reloading.
command: FILE/COMMAND=lane_s_sin.acf
command:
command: file/model=lane_s_sin
Adams Car Adams 2019
Processing ENVIRONMENT entries in 'C:\Program Files\MSC.Software\Adams\2019\acar/acar.cfg'
Processing ENVIRONMENT entries in 'C:\Users\NIKHIL/.acar.cfg'
Processing ENVIRONMENT entries in 'C:\Program Files\MSC.Software\Adams\2019\aexplore/aexplore.cfg'
OS-environment detected: MDI_CDB_SEARCH=no
Adams Car will restore the cdb search algorithm from version 12.0 (if set to 'yes').
Usage of this environment variable is strongly discouraged.
OS-environment detected: MSC_ACAR_SIM_FAIL=legacy
Adams Car will ignore the driver control file 'haltOnFailure' setting and use the Solver 'simfail' preference, instead.
OS-environment detected: MSC_ADAMS_TIRE_DIS_M_AND_I=yes
Adams Tire will not re-distribute the total wheel mass and inertia over the rim and the belt when set to 'no'.
OS-environment detected: COSIN_PREFIX=C:\Program Files\MSC.Software\Adams\2019\cosin
Adams FTire will use the user specified path to the cosin software installation.
OS-environment detected: MSC_MULTILINE_XML=1
Adams Smartdriver will use multi-line formatting when instantiating xml driver control files (0 or 1; default=1).
OS-environment detected: COSIN_EXTLIB_OPENCRG=C:\PROGRA~1\MSC~1.SOF\Adams\2019\win64\OpenCRG.dll
Sets the library to be used by the cosin software (cosin/tools and FTire) for the OpenCRG roads.
=================================================================
Adams Tire
Version Adams 2019
=================================================================
---- START: WARNING ----
IP data specified for PART model.TR_Rear_Suspension.gel_upper_control_arm
is not physically meaningful, since it does not satisfy the
requirement that Ixx + Iyy must be greater than or equal to Izz.
Dynamic analyses may fail or produce unreliable results.
The moments of inertia about the CM (or IM) are:
Ixx = 105480, Iyy = 62520, Izz = 170000
---- END: WARNING ----
---- START: WARNING ----
IP data specified for PART model.TR_Rear_Suspension.ger_upper_control_arm
is not physically meaningful, since it does not satisfy the
requirement that Ixx + Iyy must be greater than or equal to Izz.
Dynamic analyses may fail or produce unreliable results.
The moments of inertia about the CM (or IM) are:
Ixx = 105480, Iyy = 62520, Izz = 170000
---- END: WARNING ----
Creating new Sensor in service of discrete GSE/1 to manage its sampling time.
The name of this Sensor is set to (GSE/1)/Sensor/1.
(This Sensor is custom created and it is not to be found in the database.)
Creating new Sensor in service of discrete GSE/7 to manage its sampling time.
The name of this Sensor is set to (GSE/7)/Sensor/2.
(This Sensor is custom created and it is not to be found in the database.)
Reading configuration file 'C:\Program Files\MSC.Software\Adams\2019\acar/acar.cfg'
Reading configuration file 'C:\Users\NIKHIL/.acar.cfg'
Reading configuration file 'C:\Program Files\MSC.Software\Adams\2019\aexplore/aexplore.cfg'
-------------------------------------------------------------------------------
| Model Title |
|=============================================================================|
| |
| Adams Car Assembly (Adams 2019) |
| |
-------------------------------------------------------------------------------
command: !
command: !INFO Adams Version: Adams 2019
command: !INFO Adams Build: 2019.0.0-CL639814
command: !INFO Assembly File: <private>/assemblies.tbl/Nikhil_assembly.asy
command: !INFO Solver Library: C:/PROGRA~1/MSC~1.SOF/Adams/2019/win64/acar_solver.dll
command: !
command: string/5, string=lane_s_sin.xml
command: preferences/solver=CXX
command: preferences/list,status=on
PREFERENCES:
SIMFAIL = NOSTOPCF
Contact Geometry Library = (not loaded)
Thread Count = 1
Library Search Path = Not Set
Status Message = On
Solverbias = CXX (C++ Solver)
command: control/routine=abgTire::con901,func=user(901,123,99,105,1,2)
command: control/routine=abgTire::con901,func=user(901,127,100,106,1,4)
command: control/routine=abgTire::con901,func=user(901,131,108,114,1,6)
command: control/routine=abgTire::con901,func=user(901,135,109,115,1,8)
command: output/nosep
command: control/routine=abgVDM::EventInit, function=user(5,1,7,0,2,5,8,16)
vdm::EvtMonitor::EvtMonitor
End conditions evaluated in SENSUB.
ASD_vfSet_Globals()
=================================================================
Adams Smartdriver
Version Adams 2019
=================================================================
Using SmartDriver Template file:
C:\Program Files\MSC.Software\Adams\2019\win64/.smartdriver.xml
SDF_xml_upd_controller()
Info: minPreviewDistance is negative or not set, using default 5m.
Drv_Model::vfSetMaxLenItx
Info: MaxLenItx is negative or not set, using default (100m).
command: control/routine=abgVDM::EventRunAll, function=user(0)
fdm::ActJoiMot
Setting function on: steering::steering_wheel_angle
command: MOTION/4, FUNCTION=0.0
command: SFORCE/1, FUNCTION=0.0
fdm::ActVar
Connecting: steering::steering_wheel_angle
To : driver_demand::steering
fdm::ActVar
Setting function on: driver_demand::steering
command: VARIABLE/88, FUNCTION=AZ(767,1052)
command: DEACTIVATE/SFORCE, ID=4
Deactivated model.testrig.jfs_steering_rack_force.force, force/torque values will be zero in function-expression references.
command: DEACTIVATE/SFORCE, ID=5
Deactivated model.testrig.jfs_steering_rack_force.force_j, force/torque values will be zero in function-expression references.
command: DEACTIVATE/MOTION, ID=3
Deactivated model.testrig.jms_steering_rack_travel.motion, force/torque values will be zero in function-expression references.
command: DEACTIVATE/MOTION, ID=4
Deactivated model.testrig.jms_steering_wheel_angle.motion, force/torque values will be zero in function-expression references.
fdm::ActJoiFor
Setting function on: steering::steering_wheel_torque
command: SFORCE/2, FUNCTION=DIF(4)
fdm::ActVar
Setting function on: driver_demand::throttle
command: VARIABLE/90, FUNCTION=USER(976,3)\ ROUTINE=abgVDM::var976
fdm::ActVar
Setting function on: driver_demand::brake
command: VARIABLE/92, FUNCTION=USER(975,3)\ ROUTINE=abgVDM::var975
fdm::ActVar
Setting function on: driver_demand::gear
command: VARIABLE/94, FUNCTION=(4.0)
fdm::ActVar
Setting function on: driver_demand::clutch
command: VARIABLE/96, FUNCTION=0.0
vdm::SteadyState::MiniInfo
Static Task : 'Straight'
Lon. Acceleration : 0.000 [m/s^2]
Initial Velocity : 16.667 [m/s]
Perform Linear : No
Include Damping : Yes
Halt on Failure : Yes
fdm::ActVar
Setting function on: driver_demand::clutch
command: VARIABLE/96, FUNCTION=1.0
command: ACTIVATE/MOTION,ID=4
command: SIM/STAT
Begin Static Solution
TIRE ID: 2
TYR900 -> Pacejka 89 Tire Model
Using 2D Road
One point Contact
TIRE ID: 4
TYR900 -> Pacejka 89 Tire Model
Using 2D Road
One point Contact
TIRE ID: 6
TYR900 -> Pacejka 89 Tire Model
Using 2D Road
One point Contact
TIRE ID: 8
TYR900 -> Pacejka 89 Tire Model
Using 2D Road
One point Contact
STATICS: Original static solver will be used with the Sparse linear solver.
---- START: ERROR ----
Static equilibrium analysis has not been successful.
The maximum number of iterations 25, has been reached.
For the last attempted iteration:
The equation with the largest error was model.TR_Rear_Suspension.ger_upper_control_arm Comp = 8 Error = 2282653.508823
The variable receiving the largest increment was model.TR_Rear_Suspension.jolcyl_lwr_upr_strut Comp = 2 Delta = 236848.047946.
---- END: ERROR ----
Static Solution failed to converge
End Static Solution
Simulate status=-124
acar/vdm::apre_fvbcsb
**** Error:
Sim/stat cannot be achieved.
---- START: ERROR ----
Aborting Execution.
---- END: ERROR ----
---- START: ERROR ----
Adams Solver (C++) run terminating due to STOP requested by user.
---- END: ERROR ----
Termination status=-995
Terminating Adams Car usersubs...
Finished -----
Elapsed time = 4.34s, CPU time = 4.31s, 99.27%
Simulation is complete.

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