OS: Windows 8 (6.2)

Word size of OS: 64-bit

Word size of FreeCAD: 64-bit

Version: 0.19.22209 (Git)

Build type: Release

Branch: master

Hash: 9c3f9b72a82249d5fcf1f543dd69a78740251b26

Python version: 3.6.8

Qt version: 5.12.1

Coin version: 4.0.0a

OCC version: 7.3.0

Locale: Italian/Italy (it_IT)

Greetings to the whole community!

I have already posted this calculation model FEM - CalculiX on the Italian forum to give an answer to the question of “biros".

Unfortunately, to date no one has experimented with another solver if the calculation model is valid and if the calculation results are reliable.

I propose my experimentation again in the FEM forum: https://forum.freecadweb.org/viewtopic.php?f=28&t=48016

The question of "biros":

- is it possible to determine with FEM, with good approximation, the maximum load applicable to the top of the“ table ”system consisting of a support surface supported by two parallelepiped-shaped supports placed orthogonally detached from each other, avoiding overturning?

Workbenches and / or macros added:

- CenterOfMass.Fcmacro

Material assumed for the "table" system:

- Generic wood - 700 Kg / m³

CalculiX Limitations / Conditions:

- Unique solid "table" system;

- unique material (top and supports).

(It must be said that load and / or geometry patterns / forcing could be set to simulate the different materials making up the system).

Simplifying, the system can be traced back to a mere lever of the first kind, then set, through the "Spreadsheet" workbench, a simple analytical calculation which allowed me to obtain a value ("measurement meter") to be compared to that obtained from CalculiX.

For any experimentation and visualization of the results, from the link below, you can download the file: "simul_equil_ribalt_tavolo.FCStd" whose structure is as follows:

- CARICO: hypothetical surface-thrust (object supported);

- tavolo: geometry of the product;

- Analysis: FEM solver settings and results;

- PAVIMENTO: hypothetical table support surface;

- polig_equilb_ribalt: polygon / roll-over stability area;

- Cent_mas_tav_completo: center of mass table system;

- appoggio0: geometry of support "0";

- appoggio1: geometry of support "1";

- Cent_mas_appog0: center of mass of support “0” (counterweight);

- Cent_mas_appog1: center of mass of support “1” (counterweight);

- bracci-carichi: load arms and relative distances from the hypothetical axis of rotation (for the calculation of static moments);

- asse_rotazione: hypothetical axis of rotation of the "table" system;

- Cent_mas_semi_tav1S: center of mass of the hypothetical semi-table side to the detriment of overturning stability;

- Cent_mas_semi_tav2S: center of mass of the hypothetical semi-table side in favor of overturning stability (counterweight);

- max-rotazione-tavolo: maximum rotation of the center of mass of the “table” system as a whole, with respect to the overturning stability polygon;

- dimensioni_generali: general dimensions and overall dimensions of the "table" system;

- Verif_analit_rotaz_calc_semplif: simplified analytical verification max load overturning stability obtained with the Spreadsheet workbench by importing the calculation data directly from the properties of the objects;

- compl_semitavolo1S: semi-table geometry to the detriment of overturning stability;

- compl_semitavolo2S: semi-table geometry in favor of overturning stability;

Conditions:

- the settings of the constraints (displacements / rotations) are to be considered valid only for the overturning check;

- exclusively static simulation.

Simulation results:

The maximum (theoretical) applicable load that does not cause overturning, without prejudice to the constraints and forces indicated above, calculated with the FEM- “CalculiX” bench is 457.0635 N (46.59 Kg).

In fact, by increasing the value of the force (ConstraintForce) by 1 N we will have displacements "Z" with values in meters, therefore overturning with rotation in the same direction as the load resting on the plane; decreasing it, again by 1 N, there will be displacements "Z" with values in meters but with the opposite direction of rotation to that of the load placed on the plane, therefore in favor of stability.

The result of the simplified analytical calculation, equal to 375.678855 N (38.2955 Kg), was obtained by summing the moments determined by the various masses with respect to the hypothesized rotation axis.

N.B. some unit of measure values automatically set in the various cells are incorrect, therefore, refer to the one indicated in brackets in the column header.

To view the animation of the simulation: -> Analysis -> double click on "CCX_Results", in the "Actions" panel set "DisplacementZ", put the check mark on "Show" and bring the value "Max stroke to 100" ”, Then operate the selector lever placed immediately above“ Factor ”.

Furthermore, in this panel the minimum and maximum values of the "Displacement Z" obtained with the aforementioned load can be appreciated.

In conclusion, it would be desirable to share the results of a simulation obtained through the use of other solvers, with the aim of evaluating, in this case, both the validity of the calculation scheme and the reliability of the CalculiX solver.

The link: http://www.filedropper.com/simulequilribalttavolo

Good day and good job everyone!