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  1. 1 like
    Hi Paulo, I dont think so that's the problem your space in your system is more than sufficient to run this model. When something comes like this next time, just restart the software and reassign the boundary conditions for your model.
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    Glad to help. The topology stress constraint acts as a global stress control. It will filter out only the artificial local stresses caused by point loading or boundary conditions so artificial stresses will not be removed. Refer to Topology Optimization of a Hook with Stress Constraints. Those stress concentrations can be removed in the subsequent design fine-tuning stage such as size, shape and free shape optimization with DRESP1 stress constraint. The artificial stress concentrations are stress singularities due to a point load or constraint, sharp re-entrant corners, corners of bodies in contact,... For more information refer to: http://www.acin.net/2015/06/02/stress-singularities-stress-concentrations-and-mesh-convergence/ https://www.comsol.com/blogs/singularities-in-finite-element-models-dealing-with-red-spots/ https://www.digitalengineering247.com/article/dealing-stress-concentrations-singularities
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    Let me add another approach that I've just learned. There are many options to perform it but I’ve found this method very simple, flexible and self-explanatory. Summary: In the example, watertank.oml is the master file. It: changes the input parameters (controller gains) runs (repeatedly) the file Watertank_parm.scm (slave) collects results doing post-processing (plot) at the end. I’ve created a quick video to summarize how to run the demo. Present working directory must be where you save the files (the video shows how to select the pwd). Otherwise use an absolute path in the oml file. Liv ParameterSweeping.mp4 watertank.oml watertank_param.scm
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    Hi, check the units used for added masses. Their magnitudes are consistent with kg, not with tonnes which are units used for material laws. Therefore the weight of the added masses is 1000x too high.
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    I prefer Utility>Radioss Tools>RBODY manager where all rigid elements are listed with their related master nodes. There are other ways to get master node ID:
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    Hi, I think the file has initial intersection. Contact can only create penetration. Intersection is a CAD or FE issue. Check the intersections in Hypermesh using Tool > Penetration. This way it displays the intersections and penetrations part wise. I found 19 intersections in your model as shown in the attached image (displayed in white colour on grey elements). You need to merge the nodes at highlighted location. Or, move the elements away so that there isn't any intersection.
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    Hi initial velocity and gravity should include all slave nodes of a rigid body as well as its master node. Other boundary conditions require only the master node.
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    Hi, Stress constraint is not recommended in the design concept stage: topology, topography and free-size optimization.  The stress constraint definition in a topology optimization is a global constraint and does not target local stress concentrations. These areas can be addressed subsequently through size, shape, and free shape optimization or a combination thereof. Artificial stress concentrations are filtered out during topology optimization with stress constraints. These include regions around rigid connections, concentrations due to hard geometric features such as corners, etc. Stress constraints for a partial domain of the structure are not allowed because they often create an ill-posed optimization problem since the elimination of the partial domain would remove all stress constraints. Consequently, global stress constraint applies to the entire model when active, including both design and non-design regions. Stress constraints may not work well in a model where there is a large differential in response values between design and non-design spaces. In these cases, it is recommended to modify the problem formulation to say, compliance based for example. It is not recommended to use the global stress constraint along with a mass/volume constraint. The constrained mass/volume may not allow the stress constraint to be satisfied. DRESP1-card stress constraint is used in subsequent design fine-tuning stage such as size, shape and free shape optimization.
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    Hi Alessio, Currently, SimSolid only supports static stiffness for bushing elements. Output of velocity.acceleration will be available in our next release. Girish
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    Yes, they are Torques. They are resolved in the reference frame used when you created the Output to report that force. It will default to Global if you didn't create a reference frame
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    Hello Berke, Please, find attached a pdf which explains clearly the differences between Bertotti and LS methods and how to take advantage of them in Altair Flux. The reason why you cannot use the first two time steps to calculate iron losses is that it uses derivatives and to obtain the derivative in point N you need the variable values in previous points (N-1 and N-2). Best regards, Alejandro Iron_losses-Altair_Flux-Bertotti_LS_models.pdf
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    Hi, while you have increased the mass of the impactor the initial kinetic energy is still not enough to plastically deform the crash box. You can load the model with imposed displacement and obtain the energy required to deform the crashbox by plotting the total energy in Hypergraph and observing the corresponding deformation in Hyperview. Then you can use this energy as the initial kinetic energy to calculate the required velocity and mass of the impactor. There are modeling errors: the base plate of crashbox is not attached to the fixed supporting structure so it will slide sideways when loaded. the impactor has a relatively small contact area and it can lose contact during deformation. Provide some friction or use larger impactor plate the mesh quality is bad. Use F10 Check elements>3D to check the solid element quality and remesh accordingly. the impactor and some other components are meshed inappropriately by double walls, effectively halving the stresses. You have to mesh a single mid surface instead. imposed_displacement_0000.rad
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    Hi Paulo, I was able to do the simulation in 2019.3, I guess this is the Alavanca Stilo file_13 ( regarding HPDC ),( Kindly correct me if I am wrong) I am sharing the file with you Alavanca Stilo_13.icast Desculpe pela resposta tardia, pois estou em viagem. Alavanca_Stilo_13.icast
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    Seem that before *feinputwithdata2 you are missing a *createstringarray Number 8 indicates that the array has 8 items If input reader parses 8 args but not found, it's crashed!
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    Hi, There are QUAD elements, which are not compatible with 3D analysis. Go to 2D> ELEMTYPES> 2D & 3D and make sure types are as shown in the below image. If not change the tria3=SHELL3N and quad4=SHELL4N. The material table is not referenced properly. Leave your email and I will contact you.
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    Perhaps, some nastran mats and props not supported in dyna will be deleted. Or it's maybe a bug!
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    Hi, -you have created rigid with the master node on a structural element- this is not allowed. Make sure you use the "calculate node" or pick a free node (not connected to other elements) as independent node when creating rigid elements. Set Icog=3 or 4 so the master node will not be moved to CG -check unit consistency: the material properties are in tonne, mm, s so the gravity should be 9810. Also, define appropriate units in the begin card -gravity was acting in the wrong direction, so a negative scale factor was applied to reverse the direction -the boundary condition on the tilted platform constrained 1236 DOF. It should constrain 12345 instead -the contact sets between wheels and tilting platform were swapped -advanced mass scaling AMS is used instead of DT/NODA/CST mass scaling -the run time was extended to allow the bus to hit the ground -the floor is not large enough: rigid wall can be used as ground instead simple_bus_7_edited.hm
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    Hi, here is the Procedure to apply Initial_velocity around an axis 9- Procedure to apply Initial_velocity around an axis - Altair University Also, make sure to constrain de independent node of a rigid body in all other degrees of freedom. Share the model if the issue persists.
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    Great Sourav. Thank you for the suggestion! Surely the content will help a lot, I'll right now to donwload and read. Regards,
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    Please refer attached MFLUID example in OptiStruct. MFLUID.pdf MFLUID_Example.zip
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    Hi Nachiket Kadu I think by this way also we can find it out. Try this too Click Card edit > Select rigids > edit
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