Is there any way to get the principal stresses after a psd analysis at ANSYS 8.1 and later?
These values are utilized in a fracture mechanics analysis technique that is widely accepted by several of our customers.
I understand that you have gone to a new routine for computing the Von Mises stresses do to random vibration.
Is there a way to obtain the principle stresses that went into the calculation of the Von Mises stresses? |
You can issue AVPRIN,1 to obtain principal stresses calculated from the 1 sigma component stresses as was<br>done pre-8.1.
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Why doesn't coriolis moment with Solid elems agree with hand calculations? |
The attached input for the solid185 version of this test gives the expected<br>value of MY 116. It uses a transient analysis and the stationary reference frame.<br>Development... |
How do you use the various factor fields on /UNITS?
I need to use /UNITS for an ADAMS export. The model units are mm, kg, second, milli-Newton.
According to Section 12.4 of the Advanced Guide, the command should be:
/UNITS,user,1000,1,1,1,,,1000
The ANSYS output to this command (see below) implies that the factors should be reversed.
Which is correct? Please clarify.
USER UNIT SET SPECIFIED FOR INTERNAL
LENGTH = 1000.0 /METER
MASS = 1.0000 /KILOGRAM
TIME = 1.0000 /SECOND
TEMPERATURE = 1.0000 /KELVIN
TOFFSET = 0.0000 FROM ABS ZERO
CHARGE = 1.0000 /COULOMB
FORCE = 1000.0 /NEWTON
HEAT = 1.0000 /JOULE
INPUT UNITS ARE ALSO SET TO USER |
Yes, the factor should be 1000. For example,<br><br>FORCE = 1000 milli-Newtons/NEWTON<br><br>Feature request 53604 has been created to make this more<br>clear in the... |
Why is rotational inertia of MASS21 ignored in a static coriolis analysis at ANSYS 11.0?
I created a simple one element MASS21 model with all mass and rotary inertia values equal to 1
and it rotated it around x axis with wx =1000 and z axis with wz=10 in a static analysis using the
rotating reference frame (CORIOLIS,ON,,,OFF.)
The theoretical reaction moment must be MY= Ixx * wx * wz = 1 * 1000 * 10 = 10000
But ANSYS calculates a moment of 0. |
I checked with development and only the translational mass of mass21<br>is considered in a static coriolis analysis. In a transient analysis, like the one attached,<br>the coriolis... |
Why can't I get reaction forces after my PSD analysis in ANSYS 10.0 with PRRSOL? |
This occurs when the participation factor solution and PSDCOM combination<br>are performed separately. The error is corrected in 11.0 (Ref: Defect 50908.)<br><br>PRRFOR may be a... |
Why doesn't SOLID90 have the same temp-dependent film coefficient evaluation
options as SOLID70? I am using SOLID90 elements which do not have a keyoption
to specify how the film coefficient will be evaluated. SOLID70 elements have keyopt(2)
to do this. For example, keyopt(2)=1 specifies evaluation at element surface temperature, TS. |
SOLID90 has the exact same options as SOLID70 using keyopt(3) instead of keyopt(2),<br>but they are undocumented.
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Is there an error in the Harwell-Boeing Output for a CMS superelement .sub file?
Is it possible that ANSYS 9.0 does not write out the HB correctly? Or in a
format that does fully not correspond to the guide I have (TR/PA/92/86)?
The SELIST command ANSYS shows that the .sub file for my test problem has
324x324 matrices (24 nodal DOF and 300 modes). I read the matrices from
the SElist output (lower precision obviously) into Matlab as a check. Next
I read in the HB file data with no big problems. The check between the
two failed, however, so I took a closer look at the HBmat ASCII file.
The HBMAT command in this case wrote out a fully populated HB format file
(324x324 values) as if there are no zeroes and the matrix is non-symmetric.
I was expecting the document form for a symmetric matrix given MXTYPE=RSA,
that is, only the lower triangle including the diagonal with zeros
eliminated. BUT this is no big deal, particularly if ANSYS consistently
does the same thing each time.
When I examined the data it became clear that the COLPTR array from the
file would not re-construct the matrix correctly. The column pointer index
varied by 325 instead of 324 for the fully populated rows so the matrix
reconstruction loop was overwriting entries. I created a new COLPTR array
that fit the data and the subsequent matrix matched (to precision limits)
the SElist data.
My question for you is: Does ANSYS always write out a fully populated
matrix for the HBmat? If so, my current translation procedure is
sufficient & needs no change except perhaps to add provision for
transposition of a non-symmetric matrix. And in that case, would MXTYPE
change to indicate asymmetry, RUA, for example?
Also, can you verify that the last table in the SElist file before the
matrix data (Global DOF) is the correct DOF assignment for matrices?
The test model is a simple plate with the corner nodes as MDOF and 300
modes generated for CMS. |
Yes, there is an error, Defect54655, corrected in ANSYS 11.0. As you describe we<br>are off by 1 for each column in writing the COLPTR values.<br><br>Our experience so far is... |
Has the behavior of ALLSEL,BELOW,AREA (Select Everything Below selected areas)
changed recently? |
Going back to ANSYS 5.1, the documentation matches the current behavior,<br>There was a Class 3 97-40 dated Sept, 1997 that indicates<br>prior to Release 5.4, we were selecting the... |
Why does static cyclic symmetry analysis with symmetric load trigger many loadsteps?
The rotation axis is X represented by coordinate system 11. |
CSYS,11 was defined as shown below:<br><br>LOCAL,R5.0,LOC, 11, 1, 0.00000000 , 0.00000000 , 0.00000000<br>LOCAL,R5.0,ANG, 11, 1, 90.0000000 , 90.0000000 ... |
Why does my input sometimes give incorrect results when run repeatedly with /CONFIG,NPROC,2
at ANSYS 10.0? |
This is a Class 3 error (Ref: Defect 54523.). It has been corrected in 11.0.<br>The error occurs randomly when BEAM188 is run in parallel with multiple sections.
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Why do reaction forces not sum to zero in an Inertia Relief analysis with a superelement?
The documentation states that the sum of the reaction forces in a IRLF calculation
should be zero. For the attached model that uses a matrix50 element this is not true. Here is development's explanation of the non-zero reaction forces |
I reported this in Defect 54555, but development found that it was not an error. The condensed mass matrix of your Substructure is not<br>representative of the mass of the model with the... |
Why is the ADAMS macro failing on my new 64 bit workstation at ANSYS 10.0?
I get a message that the macro cannot find the superelement file: subelem.sub is not available |
The macro requires 64 bit ADAMS libraries from MSC, which we did not get in time for 10.0.<br>We will support 64 bit at 11.0.
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Why is a second TB command ignored? For example, in the input below, the
second TB command is an attempt to change TBOPT, but it is ignored.
------------
/prep7
TB,PIEZ,110 ! first TB command for Piezoelectric stress matrix[e]
MP,DENS,110,1780
mp,perx,110,7.522e-11
mp,pery,110,1.204e-10
mp,perz,110,9.735e-11
tb,piez,110,,,1 ! second TB comannd for Piezoelectric stress matrix [d]
Normal ANSYS functionality is to overwrite the previous specification as would
happen in the input below.
/prep7
et,1,186
et,1,181 |
The table data is complicated and it would be risky to just over-write<br>certain entries. It is necessary to delete the existing table before respecifying<br>the TB command as you... |
Q: Why does ANSYS 10.0 abort when I try to plot 2 way interactions for 7 Design Variables?
The main effect can be displayed.
This is Defect 55204, corrected in 11.0. The maximum 10 interactions will be plotted. |
Q: Why does ANSYS 10.0 abort when I try to plot 2 way interactions for 7 Design Variables?<br>The main effect can be displayed.<br><br>This is Defect 55204, corrected in 11.0. ... |
Why are the PSD Segalman-Reese SEQV values zero when I read them
in from a load case file? |
You need to issue SUMTYPE,PRIN before the LCASE command as shown<br>in the test... |
I have defined few parameters in Design Modeler and taken the geometry into Simulation module.
When using those variables in simulation command snippet, they are not recognized. What is required
to use CAD parameters inside a Workbench command snippet? |
The operation you desire is not possible in ANSYS Release 10.0. It is possible in ANSYS Release 11.0<br>as described below.<br><br><br>Steps in ANSYS Workbench Environment... |
Why do FSUM,RSYS results in a cylindrical RSYS differ from FSUM results
when SPOINT is specified and the same cylindrical RSYS is active. |
FSUM,RSYS transforms the individual nodal forces into the cylindrical<br>coordinate system before summing. FSUM with SPOINT sums the forces<br>in global cartesian and then transforms the... |
How does WB Solution Combination compute equivalent stress?
Is it just a summation of the equivalent stresses or is it based on
the sum of the component stresses? |
According to a developer, we combine the component stresses first and<br>then compute the equivalent stress.
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Is the get function, ARNODE( ), giving a wrong area for degenerate tet elements in ANSYS 10.0? |
Yes. I filed defect 55484 to report the error. The error is fixed in 11.0. ARFACE( ) is a possible<br>workaround.
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Why won't this variable thickness panel mesh with SOLSH190 elements with a fine mesh? |
Development explained this as follows:<br><br>This model is not really suitable for thin model sweeping when the requested element size is smaller than the<br>distance between... |
Problem finding a Workbench file associated with a DesignModeler and CFX-Mesh file in ANSYS 10.0 |
<br><br>Here is a workaround if you think that your DesignModeler (*.agdb) and CFX-Mesh file are disassociated from a Workbench database (*.wbdb).<br><br>If you do this,... |
Why is remote force incorrect in WB 10.0 when hydrostatic pressure also exists?
When I open the analysis in the ANSYS Classic environment, I can clearly see that the
position of the pilot node is not right. |
Hydrostatic pressure was a beta feature in 10.0. In this case the coordinate system<br>created for the hydrostatic pressure was not being reset to the default for defining... |
How can I get a better mapping with SUCR for higher order elements?
In a model created with curved SOLID186 elements, the SUCR command places
points as if the elements did not have curved sides.
The SUMAP command returns a warning that some of the interpolation points do
not lie on the selected elements. No results are returned for those points. |
Setting /EFACET,2 will produce a cross-section that follows the curvature of<br>the higher order elements. We have improved the SUCR documentation to<br>emphasize this in ANSYS 11.0.
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Why is frictionless support producing a torque in WB 10.0? |
The moment calculation is based on an in-accurate mesh-based estimate<br>of the centerline of the hole. At 11.0 we will be using a more accurate<br>geomety-based determination of the... |
Why does a thermal transient with contact and shell131 crash at ANSYS 10.0?
The customer is in the nuclear industry and cannot use 11.0. |
This is defect 53503 and it is fixed in 11.0. It was caused by a transient<br>smoothing routine when thermal contact and shell131 are present. The workaround<br>at 10.0 is to... |