# Result comparison **URL:** \ **Category:** General Questions\ **Created:** [March 28, 2023, 12:09pm UTC](https://prepomax.discourse.group/t/result-comparison/792 "2023-03-28T12:09:37Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\ **Post date:** [March 28, 2023, 12:09pm UTC](https://prepomax.discourse.group/t/result-comparison/792/1 "2023-03-28T12:09:37Z")
I have calculated the same construction in PPM and creo simulate I have noticed that displacement are different PPM ca 240 mm and creo simulate ca 85 mm (3 times bigger more or less) bonduary conditions material and loads are identical in both calculations. I have no idea why such big difference , stress level more less ok (the same ) best regards ![769](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/4/4fa1cbaa83aca47be1db7ada4d4f1456ac7619b5.jpeg) ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [March 28, 2023, 12:26pm UTC](https://prepomax.discourse.group/t/result-comparison/792/2 "2023-03-28T12:26:00Z")
You have to compare each and every aspect of the analysis in both programs - mesh density, element type, what you’ve already listed (maybe double-check to make sure that there are no mistakes in BCs, loads or material definitions), analysis procedure and solver settings (e.g. Nlgeom), connections (constraints, contact) and so on. ---
**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\ **Post date:** [March 28, 2023, 1:24pm UTC](https://prepomax.discourse.group/t/result-comparison/792/3 "2023-03-28T13:24:46Z")
If only displacements are not OK, check the Youngs modulus. If this is the same then the boundary condition should be checked. Check both animations. ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [March 28, 2023, 1:26pm UTC](https://prepomax.discourse.group/t/result-comparison/792/4 "2023-03-28T13:26:24Z")
You can perform a fast free-free modal analysis to compare. No loads, no BC. Just contacts in case you have set some. Mostly free to vibrate. If natural frequencies are not the same without any BC and loads, the difference could be the element type / mesh density / material properties or contacts set up. If they are the same, then you can proceed to check the BC and loads. Seems too much difference to sleep well. ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [March 28, 2023, 1:27pm UTC](https://prepomax.discourse.group/t/result-comparison/792/5 "2023-03-28T13:27:00Z")
> [@Matej](#): > > If stress is the same that means the loads and supports should be OK. If only displacements are not OK check the Youngs modulus Good point !!!.. ---
**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\ **Post date:** [April 13, 2023, 11:43am UTC](https://prepomax.discourse.group/t/result-comparison/792/6 "2023-04-13T11:43:40Z")
after checking model and recalculation (error was in one force - ![776](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/c/cf2fc23e933185b6048146328b1e13774e4b8671.jpeg) ![778](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/e/ef48f897941728d47cb53e56ed4762cc312b71f5.jpeg) ![780](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/1/1395084d612d6f9c4064f39e743fb47ea76abaf6.jpeg) ![781](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/c/c08b18f5b12daffac7bd68ca38025cc175006cd0.jpeg) wrong direction (+/-) displacement are more or less ok but next problem apperaed difference in sigma XX or in PPM sigma 11. Could anybody explain me why such difference , I have made reference model (significantly smaller size ) and result in this model was ok ---
**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\ **Post date:** [April 13, 2023, 12:36pm UTC](https://prepomax.discourse.group/t/result-comparison/792/7 "2023-04-13T12:36:22Z")
It is hard to say without more detail, but it might be the boundary condition. Are you using a rotating boundary condition and how did you model it? ---
**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\ **Post date:** [April 13, 2023, 12:52pm UTC](https://prepomax.discourse.group/t/result-comparison/792/8 "2023-04-13T12:52:31Z")
I used rigid body connection between point and named node set and I used dispacement rotation BC , for one BC I have used \*transform by calculix keywords to obtain inclined support ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [April 13, 2023, 1:10pm UTC](https://prepomax.discourse.group/t/result-comparison/792/9 "2023-04-13T13:10:54Z")
HI Mishal, I’m happy you keep going and sorting main differences. Numbers commonly refers to Local coordinate systems and letters to global. That maybe would mean your S11 is stress in the local direction and SXX is Stress in Global X direction. They may not coincide if you have set up a local coordinate system. Check principal Stresses S1, S2 and S3 first. ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [April 13, 2023, 1:46pm UTC](https://prepomax.discourse.group/t/result-comparison/792/10 "2023-04-13T13:46:05Z")
> [@Michal](#): > > I have made reference model (significantly smaller size ) and result in this model was ok What do you mean by smaller size ? What were the exact differences between that reference model and your actual model under consideration ? ---
**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\ **Post date:** [April 13, 2023, 1:58pm UTC](https://prepomax.discourse.group/t/result-comparison/792/11 "2023-04-13T13:58:56Z")
As you can see on attached photos difference is between supports in compression /axial stresses Best regards ![image001.jpg](https://global.discourse-cdn.com/free1/uploads/prepomax/original/1X/77d4802b415306da2301d22bf581a5991b958375.jpeg) ![780.jpg](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/a/aa80802f8cc37a0762232d5367329e1676fbca29.jpeg) ![781.jpg](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/c/c08b18f5b12daffac7bd68ca38025cc175006cd0.jpeg) ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [April 13, 2023, 2:21pm UTC](https://prepomax.discourse.group/t/result-comparison/792/12 "2023-04-13T14:21:05Z")
Neighter Sxx or S11 are invariants. ¿Are your sure Direction 1 is aligned with the Global coordinate system X? You comment about a \*transform card. ¿How could we visualize in Prepomax where the local direction 1 is pointing? ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [April 13, 2023, 2:22pm UTC](https://prepomax.discourse.group/t/result-comparison/792/13 "2023-04-13T14:22:14Z")
Did you check the other components of the stress tensor as well ? Maybe there are some important relations between them (like swapped directions and so on). ---
**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\ **Post date:** [April 14, 2023, 9:42am UTC](https://prepomax.discourse.group/t/result-comparison/792/14 "2023-04-14T09:42:47Z")
Someone need to remove transform feature at first model to review, be sure using exact the same geometry, material and boundary conditions. Also, mesh density and similarity in element type, quadratic is recommended. Then review the results in resultant deflection and Mises stress. If all are okay, so probably the transform is not properly assigned. ---
**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\ **Post date:** [April 22, 2023, 7:16pm UTC](https://prepomax.discourse.group/t/result-comparison/792/15 "2023-04-22T19:16:48Z")
I solved many variants with option transform and without -reaction as Rax fully horizontal from that time and difference is too big Results from Creo Simulate are much closer to reality-hand calculations ---
**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\ **Post date:** [April 23, 2023, 12:10am UTC](https://prepomax.discourse.group/t/result-comparison/792/16 "2023-04-23T00:10:49Z")
I did not found any sketch of problems (dimension, section shape, load and boundary condition) so make it hard to trace if there’s any report from analytical and Creo Simulate results also CAD files provided, maybe someone can try to reproduce the problem and clarify. But i’m still in doubt about your conclusion regarding CalculiX is so far from açcurate, probably there’s something wrong in the model ---
**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\ **Post date:** [April 23, 2023, 10:16am UTC](https://prepomax.discourse.group/t/result-comparison/792/17 "2023-04-23T10:16:02Z")
probably with model is something wrong but it is hard to find it best regards ---
**Author:** ![ANYS](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/anys/32/7737_2.png) [@ANYS](https://prepomax.discourse.group/u/ANYS)\ **Post date:** [April 23, 2023, 11:54am UTC](https://prepomax.discourse.group/t/result-comparison/792/18 "2023-04-23T11:54:54Z")
Creo Simulate could be wrong. ¿What if you request your results in global coordinates. It should be independent of any previous Transform card isn’t it. If I’m not wrong that’s done with: \*EL FILE,GLOBAL=YES S By other way I would first compare principal stresses. If they are not the same the stress tensor components will not neither. ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [April 23, 2023, 1:09pm UTC](https://prepomax.discourse.group/t/result-comparison/792/19 "2023-04-23T13:09:20Z")
> [@ANYS](#): > > \*EL FILE,GLOBAL=YES > S For \*EL FILE, the global coordinate system is used by default unless \*ORIENTATION or shell elements are used. For \*NODE FILE, the global coordinate system is used by default unless \*TRANSFORM is used. ---
**Author:** ![Michal](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Michal](https://prepomax.discourse.group/u/Michal)\ **Post date:** [April 23, 2023, 6:05pm UTC](https://prepomax.discourse.group/t/result-comparison/792/20 "2023-04-23T18:05:24Z")
problem is that only on one segment of lenght of structure stresses are different the rest is ok . so I think that problem is with model but I’m unable to solve it (as you can see on previous photos/screens [Next page](https://prepomax.discourse.group/t/result-comparison/792.md?page=2)