Hello, thanks for the great tutorial! I am redoing this in my laptop and I noticed that the version I have installed does not have the FEM Mesh Based Selection tools (to pick one specific node), this is due to the version I installed? or I have to donwload something else? Thanks!
One thing i really dont get it: the initial temperature is 25C as you prescribed, but in the final results, you can see the table and the graph showing it starting around 0C. Is it somekind of first step error? Also, congrats for the channel. I'm having a blast with those tutorials.
Right, by mistake the initial condition was applied only to the outer surface of the sphere. One should switch the selection mode to Part before selecting the sphere.
@@FEAnalyst So, for transient analisys, if you don't define the initial conditions is it 0 by default? i'm asking because i just tried prepomax transient analisys for a small project and the first temperature values were not the ones i defined, despite using "select part". For example, i used To=20C and the first value i got from the simulation was like 50C, even if i tried smaller steps. Do you have any idea of what might be happening? Thanks in advance
@@MrRenatopepin Initial temperature has to be defined for transient heat transfer analysis, at least for some nodes (otherwise, CalculiX gives an error message). If you have questions about your particular case, please ask them on the forum, it will be much easier to help there. Especially if you share your model. Issues like that are often caused by too coarse mesh but there can be other reasons too.
Not really, to be honest, PrePoMax doesn’t support any dynamic analysis steps other than natural frequency extraction at the moment. What’s more, the dynamic steps available in CalculiX (solver used by PrePoMax) are also quite limited, they are meant mainly for vibrations, quasi-static analyses and some high-speed events like impact (not the best tool for that though). Theoretically, MBD studies could be done in CalculiX but it would be very tedious to make them work with proper connections between rigid parts. By the way, CalculiX is developed by Matej Borovinšek. I just help him with documentation and tutorials ;-)
@@FEAnalyst thanks for the response. I am working on integrating FreeCAD and MBDyn to perform MBD simulatios using FreeCAD as pre and post processor. It would be fantastic to esplore the possibility of coupled simulations between MBDyn and Calculix.
@@josegegas Right, an option to use flexible bodies in MBDyn simulations in FreeCAD or to use the results of motion studies as loads in FEM analyses would indeed be great.
@@FEAnalyst Yes, exactly. My workbench will provide the dynamic loads, to be applied to flexible FEM bodies. Let me know if you are keen to try. I do not know much about Calculix and some collaboration would be great.
@@josegegas I will be happy to help with that. We can talk on the FreeCAD forum (my nickname there is NewJoker). Let me know if you need any help with CalculiX’s input file syntax.
Is it possible to define time dependent heat transfer coefficient and correspending reference temperature in a transient thermal analysis? I know to use amplitute from Abaqus, but in PrePoMax it doesn't allow to define them in a same convective load.
In PrePoMax, when you select the amplitude for the convective film load definition, it only applies to the sink temperature. To scale the film coefficient you would have to add the FILM AMPLITUDE parameter to the *FILM keyword. It's not yet supported in PrePoMax so you would have to add it manually.
@@korayozdemir8727 In this case, it would be best to export the input file from PrePoMax, add the aforementioned parameter in some text editor and run the analysis from the command line (just place the solver’s executable in the same directory as input file and type "ccx_static jobname" in the command line). Then you can open the .frd file in PrePoMax for postprocessing.
Hello, thanks for the great tutorial! I am redoing this in my laptop and I noticed that the version I have installed does not have the FEM Mesh Based Selection tools (to pick one specific node), this is due to the version I installed? or I have to donwload something else?
Thanks!
Did you click the "More" button in the Set selection window appearing when history output is defined ?
One thing i really dont get it: the initial temperature is 25C as you prescribed, but in the final results, you can see the table and the graph showing it starting around 0C. Is it somekind of first step error? Also, congrats for the channel. I'm having a blast with those tutorials.
Right, by mistake the initial condition was applied only to the outer surface of the sphere. One should switch the selection mode to Part before selecting the sphere.
@@FEAnalyst So, for transient analisys, if you don't define the initial conditions is it 0 by default? i'm asking because i just tried prepomax transient analisys for a small project and the first temperature values were not the ones i defined, despite using "select part". For example, i used To=20C and the first value i got from the simulation was like 50C, even if i tried smaller steps. Do you have any idea of what might be happening? Thanks in advance
@@MrRenatopepin Initial temperature has to be defined for transient heat transfer analysis, at least for some nodes (otherwise, CalculiX gives an error message). If you have questions about your particular case, please ask them on the forum, it will be much easier to help there. Especially if you share your model. Issues like that are often caused by too coarse mesh but there can be other reasons too.
Hi. Is it possible to perform dynamic analysis with Prepomax? Thanks for your software!
Not really, to be honest, PrePoMax doesn’t support any dynamic analysis steps other than natural frequency extraction at the moment. What’s more, the dynamic steps available in CalculiX (solver used by PrePoMax) are also quite limited, they are meant mainly for vibrations, quasi-static analyses and some high-speed events like impact (not the best tool for that though). Theoretically, MBD studies could be done in CalculiX but it would be very tedious to make them work with proper connections between rigid parts.
By the way, CalculiX is developed by Matej Borovinšek. I just help him with documentation and tutorials ;-)
@@FEAnalyst thanks for the response. I am working on integrating FreeCAD and MBDyn to perform MBD simulatios using FreeCAD as pre and post processor. It would be fantastic to esplore the possibility of coupled simulations between MBDyn and Calculix.
@@josegegas Right, an option to use flexible bodies in MBDyn simulations in FreeCAD or to use the results of motion studies as loads in FEM analyses would indeed be great.
@@FEAnalyst Yes, exactly. My workbench will provide the dynamic loads, to be applied to flexible FEM bodies. Let me know if you are keen to try. I do not know much about Calculix and some collaboration would be great.
@@josegegas I will be happy to help with that. We can talk on the FreeCAD forum (my nickname there is NewJoker). Let me know if you need any help with CalculiX’s input file syntax.
Is it possible to define time dependent heat transfer coefficient and correspending reference temperature in a transient thermal analysis?
I know to use amplitute from Abaqus, but in PrePoMax it doesn't allow to define them in a same convective load.
In PrePoMax, when you select the amplitude for the convective film load definition, it only applies to the sink temperature. To scale the film coefficient you would have to add the FILM AMPLITUDE parameter to the *FILM keyword. It's not yet supported in PrePoMax so you would have to add it manually.
@@FEAnalyst Thank you for your kind answer. İş there any tutorial or guide how to do it?
@@korayozdemir8727 In this case, it would be best to export the input file from PrePoMax, add the aforementioned parameter in some text editor and run the analysis from the command line (just place the solver’s executable in the same directory as input file and type "ccx_static jobname" in the command line). Then you can open the .frd file in PrePoMax for postprocessing.
@@FEAnalyst Thank you it works really as in Abaqus. But what is the command to run .inp as parallel?
@@korayozdemir8727 You have to set the OMP_NUM_THREADS environment variable to the desired number of cores for this purpose.