<![CDATA[MYSTRAN Forum - All Forums]]> https://www.mystran.com/forums/ Sat, 02 May 2026 22:03:16 +0000 MyBB <![CDATA[First experience creating a wingbox with M3D]]> https://www.mystran.com/forums/showthread.php?tid=117 Wed, 05 Mar 2025 19:01:31 +0000 Eduhg97]]> https://www.mystran.com/forums/showthread.php?tid=117
Last weekend I decided to try M3D out by myself for the first time. I would like it to become my main pre and pro-processor for Mystran and since efforts are being made to achieve this goal for the community, I thought it would be useful for other users to share my experience with it like the most useful tools, some pitfalls and showing the progress in general.

My only input was the set of points shaping an airfoil from the "airofoil.txt" archive located in the Examples folder. From there, with a bit of pacience and after playing around with literally every button and functionality I found, I was able to create the following model:

.png   general_view_1_no-upper-panel.png (Size: 116.69 KB / Downloads: 1)
.png   general_view_all_parts.png (Size: 62.53 KB / Downloads: 0)
.png   CBEAMS_spar_caps_&_stringers.png (Size: 46.37 KB / Downloads: 0)
.png   detailed_view_mesh.png (Size: 122.45 KB / Downloads: 0)

Things to note:
Although M3D currently lacks some automatic quad paver mesh for quads (it only has the advanced front tria mesh) I found it has huge potential for manual meshing (this is good news for some of us who like to have full control when meshing), specially regarding the 1D and 2D elements (Good for aero Smile ): My 4 most used commands here were:

    -sweep nodes to beams (to create and extend the stringers and spar caps spanwise) --> located in the menu create ---> FEM tools
    -sweep nodes to quads (to create and extend the panels and spar webs spanwise) --> located in the menu create ---> FEM tools
    -copy selected objects (acts like an overpowered reflect, ideal for placing multiple rib stations) --> available as a symbol by default
    -create quad elements from set of nodes (to create an organized cquad mesh, specially useful with curved surfaces) --> available as a symbol by default

With these four in action, the most efficient workflow I found was create first the 2D mesh of the rib that will serve as a "footprint", then build the rest of components like spar webs and caps, panel skins and stringers by extruding directly the nodes you want in CBEAM and CQUAD elements (you can specify the total length of the extrusion and the number of elements per length). This is great since you dont need an intermediate element to extrude, you just select the nodes to locate where you want to extrude directly.

The "create quad elements from sets of nodes" is one of the tools I have used the most also, it is the closest to an automatic quad meshing when the surface is not straight, very useful for curved surfaces like the ribs for example.
The "copy selected objects" command copies and translates the number of times you input an object, in this case the Rib mesh spanwise, it is like a powerful version of reflect.

After all of these action have been done, keep in mind the nodes are duplicated (between spar webs and panels, also with CBAR nodes) so in order to merge them you have to use the merge coincident nodes. I saw that it will actually merge the nodal position of each element to the one with higher or lower node label (depends on what you choose) but it does NOT merge nodes (in the sense of keeping one and deleting the other), you have to delete them after with the delete button by selecting all the model (DEL key also works for deleting the free nodes within your selection). This was tricky because being used to hypermesh each time I merge nodes, the merged nodes are deleted and I dont have to take care of them anymore, here it is a 2 steps process: Merge "nodal positions" of very close elements and then delete the free nodes.

Things I found it would be helpful to improve:

    -Preserve same filter used in repeat last command action.
    -Add mask functionality to the group management menu, it only has the ability to isolate the current group, but what if I just want to hide some particular locations of my model.
    -How to tell there are 1D elements in a 2D mesh (the quads and tria edges hide the 1D elements) when there is no property applied yet, ease the 1D element visualization.
    -Advancing front meshing does not respect nodes already existing in the model (creates connectivity problems, can't join detailed meshes with the one being created)
    -Translate option is either you know the module and direction (by key) or you specify both by the relative position of 2 objects (for example between 2 selected nodes)
     Here it would be incredibly useful if both functionalities were fusioned: You input the distance module you want, and then you specify the direction by picking 2 nodes or other set of         object that follows the direction you wish.
    -During the merge nodes task, maybe add a hint reminding the user that nodes are still there and they need to be deleted.

I find M3D a promising candidate for Mystran, once you start understanding how the program works and what it expects from you as inputs, it really feels nice and smooth, it is like a compilation of some of the most used tools in comercial pre-processors.

My intention is to continue with the model by applying properties, constraints and some typical load cases and see how it goes. Once it is finished, I will try a more complex model of a wing with some wing warping, sweepback angle and wingtips, I even plan to model the engine as a concentrated mass but well... the idea is to challenge M3D with more complex constructions.

Please do not hesitate to comment and share how you would have done something in a different way, at the end of the day I am learning the program and the more we are trying it the better for everyone.

Cheers!]]>
Last weekend I decided to try M3D out by myself for the first time. I would like it to become my main pre and pro-processor for Mystran and since efforts are being made to achieve this goal for the community, I thought it would be useful for other users to share my experience with it like the most useful tools, some pitfalls and showing the progress in general.

My only input was the set of points shaping an airfoil from the "airofoil.txt" archive located in the Examples folder. From there, with a bit of pacience and after playing around with literally every button and functionality I found, I was able to create the following model:

.png   general_view_1_no-upper-panel.png (Size: 116.69 KB / Downloads: 1)
.png   general_view_all_parts.png (Size: 62.53 KB / Downloads: 0)
.png   CBEAMS_spar_caps_&_stringers.png (Size: 46.37 KB / Downloads: 0)
.png   detailed_view_mesh.png (Size: 122.45 KB / Downloads: 0)

Things to note:
Although M3D currently lacks some automatic quad paver mesh for quads (it only has the advanced front tria mesh) I found it has huge potential for manual meshing (this is good news for some of us who like to have full control when meshing), specially regarding the 1D and 2D elements (Good for aero Smile ): My 4 most used commands here were:

    -sweep nodes to beams (to create and extend the stringers and spar caps spanwise) --> located in the menu create ---> FEM tools
    -sweep nodes to quads (to create and extend the panels and spar webs spanwise) --> located in the menu create ---> FEM tools
    -copy selected objects (acts like an overpowered reflect, ideal for placing multiple rib stations) --> available as a symbol by default
    -create quad elements from set of nodes (to create an organized cquad mesh, specially useful with curved surfaces) --> available as a symbol by default

With these four in action, the most efficient workflow I found was create first the 2D mesh of the rib that will serve as a "footprint", then build the rest of components like spar webs and caps, panel skins and stringers by extruding directly the nodes you want in CBEAM and CQUAD elements (you can specify the total length of the extrusion and the number of elements per length). This is great since you dont need an intermediate element to extrude, you just select the nodes to locate where you want to extrude directly.

The "create quad elements from sets of nodes" is one of the tools I have used the most also, it is the closest to an automatic quad meshing when the surface is not straight, very useful for curved surfaces like the ribs for example.
The "copy selected objects" command copies and translates the number of times you input an object, in this case the Rib mesh spanwise, it is like a powerful version of reflect.

After all of these action have been done, keep in mind the nodes are duplicated (between spar webs and panels, also with CBAR nodes) so in order to merge them you have to use the merge coincident nodes. I saw that it will actually merge the nodal position of each element to the one with higher or lower node label (depends on what you choose) but it does NOT merge nodes (in the sense of keeping one and deleting the other), you have to delete them after with the delete button by selecting all the model (DEL key also works for deleting the free nodes within your selection). This was tricky because being used to hypermesh each time I merge nodes, the merged nodes are deleted and I dont have to take care of them anymore, here it is a 2 steps process: Merge "nodal positions" of very close elements and then delete the free nodes.

Things I found it would be helpful to improve:

    -Preserve same filter used in repeat last command action.
    -Add mask functionality to the group management menu, it only has the ability to isolate the current group, but what if I just want to hide some particular locations of my model.
    -How to tell there are 1D elements in a 2D mesh (the quads and tria edges hide the 1D elements) when there is no property applied yet, ease the 1D element visualization.
    -Advancing front meshing does not respect nodes already existing in the model (creates connectivity problems, can't join detailed meshes with the one being created)
    -Translate option is either you know the module and direction (by key) or you specify both by the relative position of 2 objects (for example between 2 selected nodes)
     Here it would be incredibly useful if both functionalities were fusioned: You input the distance module you want, and then you specify the direction by picking 2 nodes or other set of         object that follows the direction you wish.
    -During the merge nodes task, maybe add a hint reminding the user that nodes are still there and they need to be deleted.

I find M3D a promising candidate for Mystran, once you start understanding how the program works and what it expects from you as inputs, it really feels nice and smooth, it is like a compilation of some of the most used tools in comercial pre-processors.

My intention is to continue with the model by applying properties, constraints and some typical load cases and see how it goes. Once it is finished, I will try a more complex model of a wing with some wing warping, sweepback angle and wingtips, I even plan to model the engine as a concentrated mass but well... the idea is to challenge M3D with more complex constructions.

Please do not hesitate to comment and share how you would have done something in a different way, at the end of the day I am learning the program and the more we are trying it the better for everyone.

Cheers!]]> <![CDATA[M3D - Master List of Tutorials, Videos, Learning Resources]]> https://www.mystran.com/forums/showthread.php?tid=116 Wed, 05 Mar 2025 12:54:35 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=116 First Watch - Is M3D Right For You?
-----------------------
https://www.espcomposites.com/1_M3D_Preliminary.mp4


Tutorial Series (Step-by-Step)
-----------------------
https://www.mystran.com/forums/showthread.php?tid=115
  

Official User Guide
-----------------------
http://www.m3dfea.com/user-guide.html


YouTube Videos
-----------------------
Beam Tutorial
https://www.youtube.com/watch?v=CxOtORha4mY

Constructing a Gear
https://www.youtube.com/watch?v=RIh1wPpovVw

Simple Floor Slab
https://www.youtube.com/watch?v=cS96mYU0Iuc

Basic Model
https://www.youtube.com/watch?v=vdb0Wticp3k

Mesh Beam Cross Section
https://www.youtube.com/watch?v=-pP7Uz76Gj4

Other
-----------------------
WingBox
https://www.espcomposites.com/M3D_Wingbox.mp4]]> First Watch - Is M3D Right For You?
-----------------------
https://www.espcomposites.com/1_M3D_Preliminary.mp4


Tutorial Series (Step-by-Step)
-----------------------
https://www.mystran.com/forums/showthread.php?tid=115
  

Official User Guide
-----------------------
http://www.m3dfea.com/user-guide.html


YouTube Videos
-----------------------
Beam Tutorial
https://www.youtube.com/watch?v=CxOtORha4mY

Constructing a Gear
https://www.youtube.com/watch?v=RIh1wPpovVw

Simple Floor Slab
https://www.youtube.com/watch?v=cS96mYU0Iuc

Basic Model
https://www.youtube.com/watch?v=vdb0Wticp3k

Mesh Beam Cross Section
https://www.youtube.com/watch?v=-pP7Uz76Gj4

Other
-----------------------
WingBox
https://www.espcomposites.com/M3D_Wingbox.mp4]]> <![CDATA[M3D - Tutorial Series]]> https://www.mystran.com/forums/showthread.php?tid=115 Wed, 05 Mar 2025 12:53:09 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=115
https://www.espcomposites.com/1_M3D_Preliminary.mp4

https://www.espcomposites.com/2_M3D_Intro_1.mp4

https://www.espcomposites.com/3_M3D_Intro_2.mp4

https://www.espcomposites.com/4_M3D_Solid_Beam_1.mp4

https://www.espcomposites.com/5_M3D_Solid_Beam_2.mp4

https://www.espcomposites.com/6_M3D_Plate_With_Hole.mp4

https://www.espcomposites.com/7_M3D_Plat..._Holes.mp4

https://www.espcomposites.com/8_M3D_Truss_Script.mp4

https://www.espcomposites.com/9_M3D_Mate...erties.mp4]]>
https://www.espcomposites.com/1_M3D_Preliminary.mp4

https://www.espcomposites.com/2_M3D_Intro_1.mp4

https://www.espcomposites.com/3_M3D_Intro_2.mp4

https://www.espcomposites.com/4_M3D_Solid_Beam_1.mp4

https://www.espcomposites.com/5_M3D_Solid_Beam_2.mp4

https://www.espcomposites.com/6_M3D_Plate_With_Hole.mp4

https://www.espcomposites.com/7_M3D_Plat..._Holes.mp4

https://www.espcomposites.com/8_M3D_Truss_Script.mp4

https://www.espcomposites.com/9_M3D_Mate...erties.mp4]]> <![CDATA[M3D - Pre/Post Processor for NASTRAN/MYSTRAN]]> https://www.mystran.com/forums/showthread.php?tid=114 Wed, 05 Mar 2025 12:52:24 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=114 <![CDATA[M3D Tutorials]]> https://www.mystran.com/forums/showthread.php?tid=113 Sun, 02 Mar 2025 03:16:56 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=113
https://www.espcomposites.com/1_M3D_Preliminary.mp4

https://www.espcomposites.com/2_M3D_Intro_1.mp4

https://www.espcomposites.com/3_M3D_Intro_2.mp4

https://www.espcomposites.com/4_M3D_Solid_Beam_1.mp4

https://www.espcomposites.com/5_M3D_Solid_Beam_2.mp4

https://www.espcomposites.com/6_M3D_Plate_With_Hole.mp4

https://www.espcomposites.com/7_M3D_Plat..._Holes.mp4

https://www.espcomposites.com/8_M3D_Truss_Script.mp4

https://www.espcomposites.com/9_M3D_Mate...erties.mp4]]>
https://www.espcomposites.com/1_M3D_Preliminary.mp4

https://www.espcomposites.com/2_M3D_Intro_1.mp4

https://www.espcomposites.com/3_M3D_Intro_2.mp4

https://www.espcomposites.com/4_M3D_Solid_Beam_1.mp4

https://www.espcomposites.com/5_M3D_Solid_Beam_2.mp4

https://www.espcomposites.com/6_M3D_Plate_With_Hole.mp4

https://www.espcomposites.com/7_M3D_Plat..._Holes.mp4

https://www.espcomposites.com/8_M3D_Truss_Script.mp4

https://www.espcomposites.com/9_M3D_Mate...erties.mp4]]> <![CDATA[MYSTRAN - History and Current Efforts (2025 Update)]]> https://www.mystran.com/forums/showthread.php?tid=112 Sat, 01 Mar 2025 13:05:54 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=112
https://www.espcomposites.com/MYSTRAN_Overview_2025.mp4]]>
https://www.espcomposites.com/MYSTRAN_Overview_2025.mp4]]> <![CDATA[1D Elements - Now Free]]> https://www.mystran.com/forums/showthread.php?tid=111 Wed, 12 Feb 2025 22:54:02 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=111 https://www.structuralfea.com

1D Elements© is a user friendly finite element pre/post processor that uses beam, rod, and spring elements in 2D space. It is Excel based and uses VBA (Visual Basic for Applications) to allow for advanced capability. 1D Elements is compatible with the included free MYSTRAN solver (similar to Nastran) or the MSC Nastran solver. This combination is a standard approach to finite element analysis (pre/post processer and a solver).]]> https://www.structuralfea.com

1D Elements© is a user friendly finite element pre/post processor that uses beam, rod, and spring elements in 2D space. It is Excel based and uses VBA (Visual Basic for Applications) to allow for advanced capability. 1D Elements is compatible with the included free MYSTRAN solver (similar to Nastran) or the MSC Nastran solver. This combination is a standard approach to finite element analysis (pre/post processer and a solver).]]> <![CDATA[Inertial relief in Mystran]]> https://www.mystran.com/forums/showthread.php?tid=109 Tue, 29 Oct 2024 03:05:05 +0000 Maxime56]]> https://www.mystran.com/forums/showthread.php?tid=109 <![CDATA[Composite orientation]]> https://www.mystran.com/forums/showthread.php?tid=108 Sat, 03 Aug 2024 12:30:52 +0000 trilbytim]]> https://www.mystran.com/forums/showthread.php?tid=108
It creates a .bdf file which does solve (hooray!), however the results aren't right (boohoo!). I've attached a very simple test file (.txt extension added to allow it's upload to this forum, remove to use). You can see from the PCOMP card (line 41 onwards) that I have the ply orientations all set to 45 degrees. Since this is unbalanced (there are no -45 plies) then there should be strong bend-twist coupling, so the deformed shape should show some twist, but it doesn't. Also if you manually change the values of the plies to all 0 or all 90 and re run then there is nothing like enough difference in the deflection. The difference in modulus between the two directions is about 20x, so the deflection should be an order of magnitude lower for the 0 degree case than the 90 degree case. However they're coming out very similar.

Something clearly isn't being applied correctly. I'm not sure if this is the element orientations, the PCOMP card or the MAT8 card. Any ideas, I'm a bit stumped?

.txt   FEMMeshGmsh.bdf.txt (Size: 1.74 KB / Downloads: 0) ]]>
It creates a .bdf file which does solve (hooray!), however the results aren't right (boohoo!). I've attached a very simple test file (.txt extension added to allow it's upload to this forum, remove to use). You can see from the PCOMP card (line 41 onwards) that I have the ply orientations all set to 45 degrees. Since this is unbalanced (there are no -45 plies) then there should be strong bend-twist coupling, so the deformed shape should show some twist, but it doesn't. Also if you manually change the values of the plies to all 0 or all 90 and re run then there is nothing like enough difference in the deflection. The difference in modulus between the two directions is about 20x, so the deflection should be an order of magnitude lower for the 0 degree case than the 90 degree case. However they're coming out very similar.

Something clearly isn't being applied correctly. I'm not sure if this is the element orientations, the PCOMP card or the MAT8 card. Any ideas, I'm a bit stumped?

.txt   FEMMeshGmsh.bdf.txt (Size: 1.74 KB / Downloads: 0) ]]> <![CDATA[Abaqus/CCX to MYSTRAN/Nastran Converter]]> https://www.mystran.com/forums/showthread.php?tid=106 Thu, 25 Jan 2024 13:52:31 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=106
ABAQUS to Nastran converter:
https://bor.gs/inp2nas/]]>
ABAQUS to Nastran converter:
https://bor.gs/inp2nas/]]> <![CDATA[Concern about RBE3]]> https://www.mystran.com/forums/showthread.php?tid=105 Thu, 25 Jan 2024 03:12:46 +0000 Victor]]> https://www.mystran.com/forums/showthread.php?tid=105
In my implementation, when I apply a moment load about the x axis, it causes the correct moment about x but also another moment about the y axis as shown in the attached picture. Note that the independent nodes are on an inclined face, not in a plane normal to the applied moment.

If you've used RBE3 before, would you expect this beam to bend as well as twist?

I'm suspicious of this because CalculiX has a similar issue with its moment loads on beams which are internally converted to MPCs similar to an RBE3.

.png   rbe3.png (Size: 27.95 KB / Downloads: 4) ]]>
In my implementation, when I apply a moment load about the x axis, it causes the correct moment about x but also another moment about the y axis as shown in the attached picture. Note that the independent nodes are on an inclined face, not in a plane normal to the applied moment.

If you've used RBE3 before, would you expect this beam to bend as well as twist?

I'm suspicious of this because CalculiX has a similar issue with its moment loads on beams which are internally converted to MPCs similar to an RBE3.

.png   rbe3.png (Size: 27.95 KB / Downloads: 4) ]]> <![CDATA[15.1.0 Update]]> https://www.mystran.com/forums/showthread.php?tid=104 Tue, 19 Dec 2023 14:50:01 +0000 borges]]> https://www.mystran.com/forums/showthread.php?tid=104
We separated this from 15.0 so people could have a "clean" release without this new feature, since verification efforts are still ongoing.

You can get the Windows and Linux binaries at https://github.com/MYSTRANsolver/MYSTRAN...tag/15.1.0 !]]>
We separated this from 15.0 so people could have a "clean" release without this new feature, since verification efforts are still ongoing.

You can get the Windows and Linux binaries at https://github.com/MYSTRANsolver/MYSTRAN...tag/15.1.0 !]]> <![CDATA[15.0 Released - Major Update]]> https://www.mystran.com/forums/showthread.php?tid=103 Tue, 19 Dec 2023 14:14:39 +0000 Admin]]> https://www.mystran.com/forums/showthread.php?tid=103 https://github.com/MYSTRANsolver/MYSTRAN/pull/9) and a quick summary is as follows:

All models in our current benchmark set now run without any illegal memory operations. So do other models that used to cause trouble, like cshear.bdf (part of the build verification suite) and large_shelled_beam.bdf (user-reported, I think). That doesn't mean results are necessarily correct. Not all bugs are memory bugs! But this update means that many models that used to trigger nondeterministic behaviour and/or crashes now run to completion. This way, we can actually get the results to verify they're correct, and also work on new features unencumbered by crashes.


------- SOME DETAILS --------

 - ELMOFF was comparing QUAD4 areas to an uninitialized EPS1, causing it to think positive areas were negative. The fix: initialize EPS1 to be EPSIL(1) as everywhere else does.

- GPWG had some debug prints that tried to write the value of ITABLE before it was set. The fix: move the initialization of ITABLE a couple lines up.

- ANY_U_P_OUTPUT, a variable with all assignments and uses commented out, appeared on an IF statement, thus sometimes being read even though it was never set. The fix: comment it out of the IF statement as well.

- there was a faulty conditional in the SuperLU version we were using, causing crashes when the global stiffness matrix was singular. The fix: so we changed to a more recent state of their repository since the fix was recent.
 
- a small oversight in indexes used to print CSHEAR engineering forces in WRITE_ELEM_ENGR_FORCE caused a buffer to be read past the part that actually held values. The fix: make the indexes consistent with the initialized part.

- OP2 code in WRITE_ELEM_STRESSES forgot to set a value called STRESS_CODE, used to indicate what's about to be written. The fix: put in a placeholder value for now -- there's other placeholder values in that same subroutine anyway.

- a missing ELSE was causing a fatal error to be issued for valid models containing CSHEAR cards with a nonzero OCID. The fix: added the ELSE.

- the subroutine GET_KE_OFFSET was communicating the wrong shape of BUSH element parameters (KEO_BUSH) to a matrix operation (MATPUT). The fix: communicate the correct shape.

- a post-deallocation subroutine was being called for the matrix I2_GMN regardless of whether it had been just deallocated or not, triggering a bad read. The fix: move the call into the conditional for whether I2_GMN was just deallocated.

- the SCNUM vector, containing subcase numbers, was being allocated with the wrong size, resulting in an overflow when it was written to. In MODES solutions, the "subcases" are the number of requested eigenvectors. The fix: set LSUB, which determines the maximum number of subcases in the solution, as soon was we see the EIGR bulk data card "chosen" by the METHOD case control card during LOADB. This way, all subsequent (i.e. after LINK0) allocations of SCNUM will be the correct size. There are no writes to SCNUM that could overflow before, since we set the size before the limit is even communicated to the rest of the program.

- same as above, but for EIGRL cards and the OGROUT vector. The fix: same as above, but setting LSUB as soon as we see the right EIGRL card during LOADB.

- a debug write was reading from an uninitialized variable depending on the requested data. The fix: initialize it just like in similar requests.

- okay, so, when a BUSH element has negative OCID (or the continuation card is absent), that means we use the GA-GB line as the x-axis for computing offsets. However, when GA and GB coincide, that line can't be computed, but an attempt was being made to compute them anyway, resulting in some nasty memory bugs. The fix: detect zero-length BUSH elements with negative OCID and mark them as non-offset, thus avoiding the problematic computations.]]> https://github.com/MYSTRANsolver/MYSTRAN/pull/9) and a quick summary is as follows:

All models in our current benchmark set now run without any illegal memory operations. So do other models that used to cause trouble, like cshear.bdf (part of the build verification suite) and large_shelled_beam.bdf (user-reported, I think). That doesn't mean results are necessarily correct. Not all bugs are memory bugs! But this update means that many models that used to trigger nondeterministic behaviour and/or crashes now run to completion. This way, we can actually get the results to verify they're correct, and also work on new features unencumbered by crashes.


------- SOME DETAILS --------

 - ELMOFF was comparing QUAD4 areas to an uninitialized EPS1, causing it to think positive areas were negative. The fix: initialize EPS1 to be EPSIL(1) as everywhere else does.

- GPWG had some debug prints that tried to write the value of ITABLE before it was set. The fix: move the initialization of ITABLE a couple lines up.

- ANY_U_P_OUTPUT, a variable with all assignments and uses commented out, appeared on an IF statement, thus sometimes being read even though it was never set. The fix: comment it out of the IF statement as well.

- there was a faulty conditional in the SuperLU version we were using, causing crashes when the global stiffness matrix was singular. The fix: so we changed to a more recent state of their repository since the fix was recent.
 
- a small oversight in indexes used to print CSHEAR engineering forces in WRITE_ELEM_ENGR_FORCE caused a buffer to be read past the part that actually held values. The fix: make the indexes consistent with the initialized part.

- OP2 code in WRITE_ELEM_STRESSES forgot to set a value called STRESS_CODE, used to indicate what's about to be written. The fix: put in a placeholder value for now -- there's other placeholder values in that same subroutine anyway.

- a missing ELSE was causing a fatal error to be issued for valid models containing CSHEAR cards with a nonzero OCID. The fix: added the ELSE.

- the subroutine GET_KE_OFFSET was communicating the wrong shape of BUSH element parameters (KEO_BUSH) to a matrix operation (MATPUT). The fix: communicate the correct shape.

- a post-deallocation subroutine was being called for the matrix I2_GMN regardless of whether it had been just deallocated or not, triggering a bad read. The fix: move the call into the conditional for whether I2_GMN was just deallocated.

- the SCNUM vector, containing subcase numbers, was being allocated with the wrong size, resulting in an overflow when it was written to. In MODES solutions, the "subcases" are the number of requested eigenvectors. The fix: set LSUB, which determines the maximum number of subcases in the solution, as soon was we see the EIGR bulk data card "chosen" by the METHOD case control card during LOADB. This way, all subsequent (i.e. after LINK0) allocations of SCNUM will be the correct size. There are no writes to SCNUM that could overflow before, since we set the size before the limit is even communicated to the rest of the program.

- same as above, but for EIGRL cards and the OGROUT vector. The fix: same as above, but setting LSUB as soon as we see the right EIGRL card during LOADB.

- a debug write was reading from an uninitialized variable depending on the requested data. The fix: initialize it just like in similar requests.

- okay, so, when a BUSH element has negative OCID (or the continuation card is absent), that means we use the GA-GB line as the x-axis for computing offsets. However, when GA and GB coincide, that line can't be computed, but an attempt was being made to compute them anyway, resulting in some nasty memory bugs. The fix: detect zero-length BUSH elements with negative OCID and mark them as non-offset, thus avoiding the problematic computations.]]> <![CDATA[New User facing issues]]> https://www.mystran.com/forums/showthread.php?tid=102 Tue, 12 Dec 2023 04:41:12 +0000 avi7]]> https://www.mystran.com/forums/showthread.php?tid=102
Code:
LINK  3 BEGIN
dgstrf() error returns INFO= 2101
L\U MB 6.750    total MB needed 7.648
*ERROR  9903: SUPERLU SPARSE SOLVER HAS FAILED WITH INFO =         2101 IN SUBR SYM_MAT_DECOMP_SUPRLU CALLED BY SUBR LINK3
CHECK F06 OUTPUT FILE FOR        1 FATAL MESSAGE(S)
CHECK ERR OUTPUT FILE FOR        2 WARNING MESSAGE(S)
Processing terminated. Check for error messages in output file:
Test.F06
Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL

The error in .F06 is basically the same:
Code:
>> LINK  3 BEGIN

*ERROR  9903: SUPERLU SPARSE SOLVER HAS FAILED WITH INFO =         2101 IN SUBR SYM_MAT_DECOMP_SUPRLU CALLED BY SUBR LINK3

Please tell me if there's something I need to change. The test case is very simple.]]>
Code:
LINK  3 BEGIN
dgstrf() error returns INFO= 2101
L\U MB 6.750    total MB needed 7.648
*ERROR  9903: SUPERLU SPARSE SOLVER HAS FAILED WITH INFO =         2101 IN SUBR SYM_MAT_DECOMP_SUPRLU CALLED BY SUBR LINK3
CHECK F06 OUTPUT FILE FOR        1 FATAL MESSAGE(S)
CHECK ERR OUTPUT FILE FOR        2 WARNING MESSAGE(S)
Processing terminated. Check for error messages in output file:
Test.F06
Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL

The error in .F06 is basically the same:
Code:
>> LINK  3 BEGIN

*ERROR  9903: SUPERLU SPARSE SOLVER HAS FAILED WITH INFO =         2101 IN SUBR SYM_MAT_DECOMP_SUPRLU CALLED BY SUBR LINK3

Please tell me if there's something I need to change. The test case is very simple.]]> <![CDATA[Femap model hard crash]]> https://www.mystran.com/forums/showthread.php?tid=101 Sat, 02 Dec 2023 20:41:01 +0000 borges]]> https://www.mystran.com/forums/showthread.php?tid=101
While working on K6ROT, I decided to run a simple Femap 2x2 flat plate model on MYSTRAN.

This triggers a nondeterministic crash: half of the runs yield a segfault, the other half finish with a fatal error when calling the SuperLU matrix factorization subroutine.

Of course, these decks were auto-generated by Femap, so they're nowhere near hand-crafted quality. Still, no deck, no matter how corrupt, should trigger an illegal memory access.

Attached are two version of the deck: the one exported from Femap as-is, and another with some slight changes to make it more affable to MYSTRAN (to no avail).

Something in this deck is causing MYSTRAN to pass bad data to SuperLU. I'm looking into what, how, and a fix -- but any input is appreciated.

Thanks!

.txt   plate_upforce.txt (Size: 3.98 KB / Downloads: 0)

.txt   plate_upforce_changed.txt (Size: 3.98 KB / Downloads: 0) ]]>
While working on K6ROT, I decided to run a simple Femap 2x2 flat plate model on MYSTRAN.

This triggers a nondeterministic crash: half of the runs yield a segfault, the other half finish with a fatal error when calling the SuperLU matrix factorization subroutine.

Of course, these decks were auto-generated by Femap, so they're nowhere near hand-crafted quality. Still, no deck, no matter how corrupt, should trigger an illegal memory access.

Attached are two version of the deck: the one exported from Femap as-is, and another with some slight changes to make it more affable to MYSTRAN (to no avail).

Something in this deck is causing MYSTRAN to pass bad data to SuperLU. I'm looking into what, how, and a fix -- but any input is appreciated.

Thanks!

.txt   plate_upforce.txt (Size: 3.98 KB / Downloads: 0)

.txt   plate_upforce_changed.txt (Size: 3.98 KB / Downloads: 0) ]]>