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Ivan last won the day on September 19

Ivan had the most liked content!

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  1. Ivan

    initial stresses

    Hi Marta, Mr. George P Johnson is inactive since May, which is unfortunate because his Radioss expertise is greatly appreciated. The files can be found on hard disk with HyperWorks installation: <install_directory>/demos/hwsolvers/radioss/14_Truck_with_FXB/VPG_Flexible_body/Model_EIG/TRUCK_EIG_* The model is from a Radioss tutorial RD-E: 1400 Truck with Flexible Body. TRUCK_EIG_0000.rad.zip TRUCK_EIG_0001.rad.zip You're welcome.
  2. Hi, you can try the following: -recreate geometry from FE: Geom>surfaces>from FE and if there are solids combine the surfaces with Geom>solids>Bounding surfaces -if you have CAD geometry file: import geometry and then associate the nodes to geometry by Geometry>Edit>Nodes>Associate
  3. Ivan

    Incompatible attribute (ATTA) item codes

    Hi luckyluke, please look into the attached attribute compatibility chart. DRESP1 - Responses and Attributes.pdf
  4. Ivan

    Hypermesh study guide

    Hi Bakr Amine, in addition to Premanand's suggestion I would also recommend the following Youtube channels for practical demonstrations: Altair University Altair India Student Contest ELEATION By Apoorv Bapat
  5. Ivan

    BC with certain displacement allowed

    Hi Daniel, I do not think that Boundary conditions can model such behavior directly, as they do not allow to be updated during the simulation. My suggestions would be to model end stops as: -type 4 springs attached between cylinder nodes and dummy nodes with fixed BCs and non-linear stiffnes curve to model end stop constraint. -contact interface defined between 2 rigid planes with fixed BCs perpendicular to x axis at the limit distance as master surfaces and cylinder nodes as slave.
  6. Hi, I think the issue is because kinetic relaxation option is turned on (/KEREL), which is effective for settling under gravity load (see dummy positioning example), but is not appropriate for imposed displacements. In the model you have shared there are no incompatible kinematic conditions. However, there are some minor issues with the set up of simulation: -tied interface are referring to default type2 interface definition, which is not given -there are a total of 33 nodes for which no master surface is found during starter -the mass scaling is turned on but no timestep is defined (1e-2 will give mass error below 2%) -there are no boundary conditions (constraint) applied to Acetabulum, however the simulation still gives some displacements (in the order of 5e-3)
  7. This method will slightly change the element proportions near projected edge nodes (compared to the base mesh). If the gap is too big it might lead to linear 1D elements at those edges not in alignment with the rest. But I hope it will Hyperwork
  8. Ivan

    door Closing Analysis

    Hi Nagarjuna Gundamsetty, I would suggest Motionsolve, which is a Multibody Dynamics solver. Please refer to the tutorial MV-2021: Simulating an Automotive Door Closure Event. You may also find useful the presentation from 2nd European HyperWorks Technology Conference: Door slam simulation for durability analysis with Multibody Dynamics.
  9. Hi Burner2k, after projecting the original mesh to surface, you could project those edge nodes to line in order to close the gap.
  10. Ivan

    *DOUBT* RBE2 & RBE3

    Hi, RBE2 and RBE3 are rigid links in FEM used for load transfer. These elements in fact will not deform as they are considered to be infinitely rigid (diamond under atmospheric pressure for example even though it's not infinitely rigid) and the sole purpose of these elements is to transfer the loads between the grid points or nodes. RBE2 transfers the loads in such a way that all the slave (dependent) nodes have zero relative deformation after the load application. Whereas RBE3 transfers the load using weighted average of slave nodes(independent nodes) position. Perhaps you will understand even better: https://iberisa.wordpress.com/2015/10/13/rbe2-vs-rbe3-on-femap-with-nx-nastran/
  11. Ivan

    About HM, Flexible bodies

    Hi LOKESH KATARI, you are probably referring to Flexible body generation using the CMS modeling technique, integrated with multibody analysis if the model is set up in OptiStruct for multibody dynamics. This method uses linear superposition of modes computed using the Component Mode Synthesis (CMS) method. Several variants of CMS exist, each attempting to accurately capture the deformations and boundary conditions with a minimum number of modes. A CMS-based flexible body contributes degrees of freedom equal to the number of CMS modes in addition to the six degrees of freedom associated with the rigid body motion. This body is able to handle small or linear deformations only. If you are interested in theoretical background refer to the attached file. Non-Linear Finite Element (NLFE) body: This method uses the “Absolute Nodal Coordinate Formulation” to obtain a fully non-linear finite element representation of the flexible component. As the name suggests, this body is defined with respect to the global frame and does not have a local part reference frame like the linear flexible body. Each flexible component can be made up of several finite elements that represent flexibility in the component. Similar to traditional finite elements, this flexibility is determined by the geometric and material data specified for the elements. The NLFE body allows you to model geometric non-linearity (large deformations) as well as material non-linearity (hyper-elastic materials like rubber). Current support for the NLFE body is limited to BEAM and CABLE elements only. These elements are useful in modeling long, slender structures. Since this representation is fully non-linear, no reduction analysis (like CMS) is required to create this body – the body can be created and modified entirely within MotionView/Optistruct without the need for any FE solver based pre-processing. For more information on the NLFE body, refer to the Body: Flexible modeling component. Theory.pdf
  12. Hi, from Radioss help: Maybe you could model bonding with springs?
  13. Ivan

    Getting error in optistruct

    Shift+F2>clear all
  14. Ivan

    Getting error in optistruct

    Hi, there are two possible reasons: -force/moments were applied on temporary nodes -moments were applied to solid element nodes, which do not have rotational degrees of freedom please follow the links to resolve the issue or share the model
  15. Ivan

    Compliant Revolute Joints

    Hi Stefano, revolute joints can be modeled with compliance in all DOF (equivalent to bushing). This can be done with Allow compliance option at the time of joint creation. The motion can be given to such joint, but it must be defined using i and j markers of the compliant joint instead of directly on a joint.