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Ivan

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Everything posted by Ivan

  1. Ivan

    Topographieoptimization - Beadfrac

    The idea of first performing optimization at the lower and upper bound of beadfrac parameter is to gain an understanding of the range of performance metrics you are trying to improve. In the following step (minimize beadfrac as objective) use the relevant performance metrics from upper/lower beadfrac optimization runs as constraints to formulate a reasonable/feasible optimization problem. The optimization to minimize beadfrac can be run with initial beadfrac=0, but you can also run with initial beadfrac at lower and upper bounds (-1 and 1) to evaluate if the design converged to local or global optimum.
  2. Ivan

    Plot Head Injury Criteria in Hypergraph

    Hi, you need to load the Vehicle Safety Tools preference file in HG (File > Load > select Vehicle Safety Tools > Load) Next, injury>HIC>Hic-Curve, chose the acceleration curve (shift+click) and set 36 ms windows length and finally clicked on apply.
  3. Ivan

    Element Orientation

    Hi, for material orientation review/edit use 2D>composites>material orientation panel. To assign nodes to a cylindrical coordinate system use analysis>system>assign panel. In the same panel, there is also an option for material orientation.
  4. Maybe the contact was not detected because shell thickness is smaller than the gap between solid and shell midsurface. Measure the gap (F4) and use Vicinity tolerance instead and provide a slightly increased gap. If other unwanted contact pairs are then detected consider creating the problematic contacts manually.
  5. Ivan

    How to remove intersection in solid elements

    Also try interface type 24: Try setting similar flags to type 7 crash recommended setup
  6. Ivan

    time step calculation

    Hi, the difference is because the characteristic element length is computed differently for shell and hexahedral elements: -Quad Shell: The square root of the shell area The critical length can vary with: • Shell formulation • Hourglass control parameters • Numerical damping • Membrane damping -8-node Hexahedral: Volume / largest face area I think the characteristic element length should be the same if element shape is close to ideal (square and cube), but could be different for distorted shapes.
  7. Ivan

    How to remove intersection in solid elements

    Hi, clearing intersection in this model should be easy- just translate one of the components in z-direction so there is a small gap, that is required for contact type 2 (tied) and 7 (general). If no physical gap is required then go for type 20 contact. Share the model if the issue persists.
  8. Glad to hear it is working. It's not working when the master/slave are swapped because nodes lying on the master surface can freely penetrate on slave surface. Interfaces are based on master / slave treatment. Contact can only occur between a set of slave nodes and a set of master segments. Master segments are defined depending on the type of element they lie on. If it is a 3-node or a 4-node shell, the segment is the surface of the element. If it is a solid element, the segment is defined as a face, Finally, if it is a 2D solid element (quad), the segment is a side. Check the following documents: https://insider.altairhyperworks.com/wp-content/uploads/2015/07/T-T-1119-OptiStruct-Defining-master-and-slave-roles-for-contact-surfaces-in-a-contact-pair.pdf http://blog.altair.co.kr/wp-content/uploads/2013/03/CONTACT_Card.pdf
  9. Ivan

    Topographieoptimization - Beadfrac

    Hi, the attached subchapter from Free eBook: Practical Aspects of Structural Optimization (A Study Guide) should be helpful. If the issue is not resolved share the .out file or the model. beadfrac.pdf
  10. Hi, choose the nodes on the edge as slave and use node to surface contact (DISCRET=N2S). Note however the contact surfaces of solid frame will only engage one node (at the corner of shell) when displaced in positive z-direction, because the shell mesh is so coarse only one node overlaps contact surface. Check the sample model with edge to surface contact. edge_contact.fem
  11. Ivan

    Displacement load

    Create a rigid body on impactor cylinder and then constrain its independent/master node in all DOF and apply the SPCD on the same node. Attached is the edited model. Check the modifications and compare to 3pt bend example. The analysis takes a lot of iterations to converge so perhaps there is a more efficient analysis setup. ESE in the global output request will output strain energy and strain energy density. steel_20kN_SPCD_edit1.hm steel_20kN_SPCD_edit1.h3d
  12. Ivan

    Displacement load

    Create rigid body using 1D>rigids. Boundary conditions are applied on the master/independent node. Output requests like displacements, forces,... can be requested by Analysis>output block.
  13. Ivan

    Changing hole location

    Hi, try with Geom>dimensioning However, for Hyperstudy parameterization Hypermorph should be used. Hypermorph is a really powerful tool, limited only by user's imagination
  14. Ivan

    Remaining time increasing.

    You're welcome! The following document could also be helpful (from Radioss Help) Interface Hints.pdf
  15. Ivan

    Bolt Pretension

    Hi, the best way is to use Pretension manager Pretension Manager - Altair University check the following examples and tutorials: OS-T: 1390 Pretentioned Bolt Analysis of an IC Engine Cylinder Head, Gasket and Engine Block System OS-E: 0015 Pretension Analysis using Gasket Material OS-E: 0140 Pretension Analysis of Piston
  16. Ivan

    How to mesh a sphere in Hypermesh

    never mind as @Rahul R already posted the same video
  17. Ivan

    Remaining time increasing.

    Hi, the recommended values for type 7 contact are already posted above, only the Gapmin parameter is model dependent. Review the energy balance in Hypergraph by loading the runname_T01 file and plot total, kinetic, internal, hourglass and contact energies. Review timestep evolution throughout the simulation. Compare the plots and try to identify the issue. Please go through chapter 17 Checks During & After Analysis in already mentioned free Radioss ebook (attached below). There is no specific procedure for checking edge-edge penetration- just carefully observe the animation in slow motion and look out for element edges crossing- it helps to display Shaded elements and mesh lines. It can be helpful to request contact vector output by eng/anim/vect flags CONT and PCONT to check in animation where and when high contact forces occur. If still unsure, set up type 11 line interface (or type 19, which is a combination of 7+11). Crash_Analysis_with_RADIOSS.pdf
  18. Ivan

    Element Normals

    Hi, element normals of 3D elements always point outward. Element normals of 2D elements can be reviewed and edited in the Mesh Editing>Part>Sheet>Orientation panel. In Hypermesh: 2D>composites>element normals Note that interface type 7 is a non-oriented contact, so a node can impact on both sides of a master segment.
  19. Ivan

    Remaining time increasing.

    Hi, there is a secure dropbox, however I will not be able to access it as I am not (yet) affiliated with Altair. If you are concerned to share publicly due to confidentiality reasons, maybe you can set up somewhat different model with similar problem. Sometimes the physics of the problem involves large contact forces in which case timestep drop is unavoidable. Another reason for timestep drop is because Interface type 7 does not deal with edge to edge impact. When the mesh is fine enough, edge to edge penetration is often followed by a node to shell contact. The main problem with edge to edge impact is the locking situations. If there is a change of load after edge penetration, locking is unavoidable since a node to surface contact is detected. This usually leads to high penetration; therefore, the analysis comes to a standstill as time step is reduced. If locking occurs, the use of interface type 11 in this area is necessary to solve the problem.
  20. Ivan

    Remaining time increasing.

    Those contact settings are recommended for crash analysis, but it can also be used in other applications. You can try increasing the Gapmin in your TYPE7 interface which will allow the contact to work sooner and prevent node from penetrating so far. Its also possible to use /DT/INTER/DEL in the engine file, and where if this time step is lower than the value given in this option /DT/INTER/DEL, the slave node is suppressed from the interface. Check the FAQ from Radioss Help on Timestep in the attached document. It is really difficult to give useful advice without seeing your model. Time Step.pdf
  21. Ivan

    Remaining time increasing.

    Hi @vishruthdilip the following might help you understand the contact timestep (from Free eBook: Introduction to Explicit Analysis using RADIOSS – A Study Guide and Radioss Help): Share the model if the issue persists.
  22. Ivan

    2d meshing on midsurf

    There was a misunderstanding- you probably meant no instead of now. To access the Midsurface Thickness Map, from the menu bar, click Mesh > Assign > Midsurface Thickness. The tool displays in a new tab in the tab area. Also try Mesh>assign>midmesh thickness.
  23. Ivan

    2d meshing on midsurf

    Hi, check the following topic:
  24. Ivan

    Displacement load

    Hi @Amasker the B-pillar three-point bend problem would require non-linear quasistatic or dynamic analysis due to three major nonlinearities: -large displacements/rotations/deformations -material yielding -contacts In dynamic analysis, inertial effects and momentum are included (loading in 0.2s) while quasistatic simulates very slow movement. Please go through free eBook: Introduction to Nonlinear Finite Element Analysis using OptiStruct The following videos should help: Learning Video: RADIOSS - Altair HyperWorks Insider OptiStruct Nonlinear Learning Center Try to replicate in your model the analysis setup from the example shared by @Rahul R
  25. Global integration (N= 0) is only compatible with Material Laws 1, 2, 22, 36, 43 and 60.
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