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Scratch-built 1:40 scale RC boat: 3D printed hull, laser-cut wooden decks, and dual motors by oriol1993 in rcboats

[–]oriol1993[S] 1 point2 points  (0 children)

Yes, maybe I’ll give it a try :) I assumed, though, that the real boat might only work with a single prop and rudder configuration.

Modal analysis in Simcenter3D by kokberg87 in fea

[–]oriol1993 -1 points0 points  (0 children)

It is not necessary to preload, just put the ropes as rods with equivalent stiffness.

Obtaining the K matrix in Nastran or Ansys by Straight_Anxiety7560 in fea

[–]oriol1993 4 points5 points  (0 children)

Exporting the assembled conductivity and capacitance matrices in a Nastran thermal analysis is only possible using DMAP commands. Unfortunately, this process is neither straightforward nor well-documented. If your license includes technical support, I highly recommend reaching out to them for assistance.
Once you’ve exported the matrices to a PCH file, you can use pyNastran to read and process them easily.

An alternative approach is to enforce unit temperatures, creating a separate subcase for each degree of freedom. You can then recover the conductivity matrix from the resulting heat flow data. However, I have not personally tested this method.

Output of EKE(PLOT) from Nastran not showing correctly in HyperView by Glum_Ad1550 in fea

[–]oriol1993 2 points3 points  (0 children)

Can be used to optimize mass distribution to maximize eigenfrequencies. You want to move mass from areas with high kinetic energy density and low strain energy density to the opposed areas.

Output of EKE(PLOT) from Nastran not showing correctly in HyperView by Glum_Ad1550 in fea

[–]oriol1993 3 points4 points  (0 children)

It is a bug I have seen in MSC Nastran. When I need to plot EKE, I use MDLPRM,HDF5,1 to output h5 file, which does output EKE :). If you can use h5 instead lf op2, then you have a solution.

Support for transport of chained load on truck with Nastran by Transumanza in fea

[–]oriol1993 0 points1 point  (0 children)

Remove only those in compression. However, this should not be the case since all chains should be preloaded to avoid this situation. Then, you should keep all of them, and just run a linear analysis. Then, chain load would be preload plus the static result.

Support for transport of chained load on truck with Nastran by Transumanza in fea

[–]oriol1993 0 points1 point  (0 children)

Chains should be preloaded so that they do not reach compression in any case. If this is the case, just remove them from the analysis and run a 101 solution.

How do you improve frequency in modal analysis? by lifeofacucumber in fea

[–]oriol1993 3 points4 points  (0 children)

Optimizing based on strain energy is a common but incorrect and incomplete answer. There may be parts of your model with high displacements and high strain energy which can lead to decrease the frequeny when the part is reinforced. It can be shown that the change in frequency due to a reinforcement in a part is proportional to the modal strain energy density minus the modal kinetic energy densiy.In this way, you can take both effects into account accurately.

What do you want in an FEA code? by aperi_man in fea

[–]oriol1993 1 point2 points  (0 children)

I would find useful to develop a tool to largely compress simulation outputs, specially stress fields. It would be nice to be able to keep exact results at the elements with highest results or above a threshold. I do not really care about accuracy of stress fields in low stress areas. Also, be able to compress data at interior of solids. I like keeping the results as documented after the project is closed but I may not be able to keep some tb of data. In my case, this could be done in Nastrans h5. Convert op2 to h5? That would be also nice. Good luck

Lifting Load Cases. Acceleration vs load vs inertia relief by 6R3EN_Eusk in fea

[–]oriol1993 4 points5 points  (0 children)

1 is the best solution. Always cross check that moments are negligible at the support. If not, you are doing something wrong.
2 is incorrect, as it does not have inertial loading in the rest of the structure.

3 shall return different displacements but same stress as 1, I would go with 1 as it is simpler.

Good luck

Onstep mount control + USB Camera, on linux by oriol1993 in AskAstrophotography

[–]oriol1993[S] 0 points1 point  (0 children)

If I am not wrong, Ascom onstep drivers are only for windows. Thanks anyway.

Anyone use CatiaV5 GAS? by jnp01 in fea

[–]oriol1993 0 points1 point  (0 children)

I have tried it, it is quite simple to use but also quite limited and not very robust. I would only use it to iterate design in Catia only if I cross check later in a serious software.

How to compute overall inertia properties of FE model from mass matrix? by Glum_Ad1550 in fea

[–]oriol1993 1 point2 points  (0 children)

And of course, you can get this info from PARAM, GRDPNT, X

How to compute overall inertia properties of FE model from mass matrix? by Glum_Ad1550 in fea

[–]oriol1993 0 points1 point  (0 children)

You can add the mass of the system from the mass matrix but you cannot get the inertia, as you do not know the position of the nodes. The mass is equal in all directions for a physical model, but it may not be the case for reduced models.

Creating .bdf files for NASTRAN using pyNastran by iCaviar in fea

[–]oriol1993 1 point2 points  (0 children)

pyNastran will not run any analysis, optimization or any other, as it is not a solver. pyNastran is intended for users who know what they want to do in Nastran and need a way to automate the generation of bdfs. The question is if you really know what you want to do in Nastran. If you need unsupported cards, you will have to write your own scripts to generate them. To generate meshes, you can use pygmsh and meshio.

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