Thanks,
my problem is, like I mentioned, that I can not change the material propertias as you suggested.
I have to simulate a specific real existig carbon composit material and therefor the material properties are fixed...
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Re: More error messages
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Re: Plate Buckling Analysis Using Symmetry Boundary Condition
Quote from PrakashPagadala on April 7, 2014, 02:45 Hi, can you make the following changes and check the results for the quarter plate? For Y symmetry, you have constrained in 246, make it to 24 and allow rotation in Z which means no translation in Y direction and no rotation in YZ plane. Similarly, instead of 156, make it to 15, no translation in X direction and no rotation around Y axis. also when you say clamped for shell elements, it means no rotation and no translation. So all DoFs should be active. in the picture I see only 345 are active.Thank you for your advice, I will have a go for it. And in terms of " clamped", I mean the plate is restrained from out of plane movement. So I constrained z displacement and rotation in yz and zx plane. Is this reasonable? And I also believe that this is the reason I have to use symmetry boundary condition to do the analysis. Otherwise I would not be able to apply correct boundary conditions since the plate is basically floating in xy plane.
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Re: More error messages
Hi Matze,
is there a specific reason for using /MAT/LAW12?
can you try running the analysis with /MAT/LAW25?
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Re: Differences between analytic and Radioss solutions in modal transient dynamic analysis
Hi,
Sorry for a late response,
could you please let me the location at which you are looking at the results?
is it the excited point?
also, the OMEGA used in equation is it 11/s or 1/s? (1 1/s is what furnished in your previous post)
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Re: Linear Buckling Analysis
Hi Alex,
the Magnitude for buckling modes F value gives the buckling load factor from which you can calculate the critical load that the structure can stand before buckling.
say for instance, I have applied a load of 100N and my buckling mode value is 0.8. this means the critical load that the strucure can stand is less than or equal to 0.8*100 which is 80N. So, the structure will buckle if 100N is applied on it.
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Re: Differences between analytic and Radioss solutions in modal transient dynamic analysis
Hi,
no problem.
We are looking at the results at the point, where the mass is applied, because its the only point of the two which can be displaced. Yes, Its the excited point.
The OMEGA is 1/s --> 1 s^(-1)
Thanks and regards
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Re: Linear Buckling Analysis
All,
The short answer is that the contour you see is the contour of the normalized values of a particular result of the linear buckling analysis called Eigenvector δm
δm is the associated buckling displacement shape for a particular mode.
Eigenvectors δm are the primary result in a buckling analyses, they are normalized with respect to the maximum vector component, (to put it simply the maximum vector value is taken as 1 and the rest of the values are taken equivalently) using which the mode shape is plotted.
This same mode will also have a particular eigenvalue λm this is called the buckling load factor. Use the following table to interpret the BLF for engineering purposes
![Image]()
we know the applied load of course as referred to in the above table,
How do we obtain these two values λm and δm?
The problem of linear buckling in finite element analysis is solved by first applying a reference level of loading, pref, to the structure. A standard linear static analysis is then carried out to obtain stresses which are needed to form the geometric stiffness matrix KF. The buckling loads are then calculated by solving an eigenvalue problem:
|K + λm KF| δm = 0
Where K is the stiffness matrix of the structure and λm is the multiplier to the reference load. The solution of the eigenvalue problem generally yields n eigenvalues λm , where n is the number of degrees of freedom (in practice, only a subset of eigenvalues is usually calculated). The vector δm is the eigenvector corresponding to the eigenvalue.
we know the applied load of course as referred to in the above table,
How do we obtain these two values λm and δm?
The problem of linear buckling in finite element analysis is solved by first applying a reference level of loading, pref, to the structure. A standard linear static analysis is then carried out to obtain stresses which are needed to form the geometric stiffness matrix KF. The buckling loads are then calculated by solving an eigenvalue problem:
|K + λm KF| δm = 0
Where K is the stiffness matrix of the structure and λm is the multiplier to the reference load. The solution of the eigenvalue problem generally yields n eigenvalues λm , where n is the number of degrees of freedom (in practice, only a subset of eigenvalues is usually calculated). The vector δm is the eigenvector corresponding to the eigenvalue.
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Re: Buckling optimization
Alex
This is regarding the theory of the optimization algorithm,
firstly are you doing a size optimization? what are the results you currently see for the optimization with buckling constraints in your model?
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ERP- Output of an Frequency Response Subcase in .csv- file
I'm simulating a frequ. resp (modal) loadstep and my output is the ERP_value.
It is no problem to get the Output sorted by frequenc in a .pch file, but want to use this output in excel. Is it possible to get the output in a formated .csv-file. So I can esaly open it in excel?
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Re: User Defined Optimizer - XOPT
Alex,
An optimizer will appear in the user-defined pull-down menu if it is registered in the current preference file. to register see
Orientation and Fundamentals > Customizing HyperStudy > Registering an External Optimizer
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Re: ERP- Output of an Frequency Response Subcase in .csv- file
Mr.Fliffer,
The quickest way now is to just plot this .pch in Hypergraph, plot of ERP panel results vs loading frequency
Then go to file > export > curves > excel and export the curve to excel.
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Re: ERP- Output of an Frequency Response Subcase in .csv- file
You are right.
But is their a way, to get the .csv directly from the OptiStruct solver, like with NASTRAN?
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Setting card image
Dear support,
I am working with a large assembly in HyperMesh and I have exported it in radios block format. I have imported it into Hypercrash and I attributed all contacts, materials, properties.
When I tried to simulate the model it gave the error that the parts do not exist. I have checked the model and I found out that I forgot to select “card image = part” in hypermesh. I would like to ask how can I set the card image in HyperCrash ?
(If I import the model in hypermesh and export it again I need to attribute all properties and materials again and I would like to know if it is possible to avoid this re-work).
Thank you for your help.
Best regards
Vitor
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Re: ERP- Output of an Frequency Response Subcase in .csv- file
I am afraid Optistruct does not output .csv
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Re: To run a model of over 33 million tetrahedral elements
Dear Rahul Ponginan,
I am sorry for returning late. I thus updated the new version as you suggested. This time the consequence is similar as the last time, except the output errors:
*** INTERNAL PROGRAMMING ERROR ***
in file "prep_1.F", at location # 1987.
ioerr(1) =-2081511776
ioerr(2) = 1
ioerr(3) = 78
**** ABORTING RUN DUE TO AN INTERNAL ERROR ****
Furthermore, after updating I can not find the User profile: RADIOSS Bulk. Hereafter are information of the update.
Best regards,
N.H. NGUYEN
Altair Home: C:/Program Files/Altair/12.0
Updates Information:
------------------------------------------------------------
acusolve12.0
hwdesktop12.0
hwdesktop12.0.110
hwdesktophelp12.0
hwdesktophelp12.0.110
hwsolvers12.0
hwsolvers12.0.210
hwsolvers12.0.212
hwsolvershelp12.0
hwsolvershelp12.0.210
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Re: Setting card image
Hi Vitor,
Perhaps you can import into Hypermesh > create part card image for the components > export just the parts > import original deck in HyperCrash > right click on part > replace 1 part by 1 part or replace full system and check
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Re: To run a model of over 33 million tetrahedral elements
Hi N.H. NGUYEN
RADIOSS bulk is also called Optistruct now, Just choose the optistruct user profile for the analysis not RADIOSS.
If you still see the error, I am afraid I will need the model again as the old file has expired.
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Connectors errors + software crash
Hello,
I am actually trying to model a full wireframe chassis using shell elements and connectors to simulate the welding but I encounter the following error message
*** ERROR # 173 ***
A dependent d.o.f. defined more than once in rigid element entry.
GRID ID = 2
component = 1
*** ERROR # 179 ***
The dependent d.o.f.s of multi-point constraints produces a singular matrix.
This may be caused by a circular dependency in which a d.o.f. is
indirectly dependent upon itself.
*** ERROR # 192 ***
Possible programming Error :
Unexpected error condition from subroutine "xdseex"
ioerr(1) = 725
ioerr(2) = 0
***** PROGRAMMING ERROR *****
I know that the 2 first errors are related with the definition a connectors where a node belongs to two (or more) different connectors and thus create a dependency, but how can I solve this problem without deleting the connectors?
However I have no idea what is the error 192 related to and how can I solve it.
Could you help me please?
Thank you
Albain
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Re: User Defined Optimizer - XOPT
Thanks. I've registered the optimizer, but I'm still having issues running it HyperStudy. Could I send you my files to look over?
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Applying a force to a different node
Hello,
Does anyone know how to apply a force to a different node without recreating it (just updating the point of application)?
Thank you for your help.
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