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      Please click here for a short but important announcement   03/26/17

      Dear Users Our Commercial and Academic users around the world can use these same forums here as before i.e. the Altair Support Forum , Commercial users from India with solver queries can go to the Solver Forum for India Commercial Users , Academic Users from India and AOC India Participants are requested to go to the Forum for India Academic Users and AOC India Participants , We will be tending to all queries in all the forums promptly as before, thank you for your understanding. 

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Found 16 results

  1. Hello, I am looking to constrain a hole of a 3D model. I am currently using RBE2s (with all 6 DOFs on) within the hole and applying a constraint to the independent node in all 6 DOFs. Doing this I am able to successfully run the optimisation. However, I want to simulate a bar constraint where the model can rotate about the y axis but no others. I have tried deselecting the 5th DOF on both the RBE2s and constraint but this results in the optimisation failing. How do I go about applying constraints to all DOFs but 5 (moment around the y-axis)? Additionally, I am using RBE2s currently as I can apply a constraint to these. However, ideally I would be using RBE3s as these will better represent my problem. Is this possible to set up with the constraint in limited DOFs in mind? Thank you
  2. Hi Everyone , I have a question , How can I create a rigid plate as bottom (all dof locked) and rigid plate as top to apply force (all dof locked, except vertical translation) in a simple cubic model (Say 10mm x 10mm x 10mm). Should I just constraint bottom surface to ( all dof locked ) and top surface to ( all except vertical ) and apply force on all nodes on the top surface ? how i can do this rigid plate thing on my model , can anyone help me ? thanks in advance . Kind Regards, Muthu .
  3. Analysis problem

    Hello Getting a problem in analysis, my 3D geometry goes into single plane during analysis.
  4. Textbox near dof in Constraints

    While analysing, we need to input constraints as BC. In constraints, there is checkbox and value for dof1,dof2,...amd so on. Checkbox is for enabling or disabiling dof, Why there is a text box for entering value? What does it siginifies?
  5. Hallo Everyone, I have created an lattice structure unitcell (BCC) of 1mm x 1mm x 1mm in CAD with that I created a whole component of 10mm x 10mm x10mm so there are 1000 unit cell in my component. I imported that component into hypermesh and it shows 1000 individual components in the model section. I want to analyse the component by applying load on the top face by constraining all the dof at the bottom and do the convergence study ( mesh refinement) . My questions are 1) how can I combine or merge all other component 1000 individual components in to a single whole as one component, I think it would be better for meshing and further analysis. ( I have attached the file for your reference please take a look) 2) How can I create a rigid plate on the bottom for locking all the dof and also rigid plate on the top for locking all dof except vertical translation for applying loads ) Thats all my questions , Please take a look on my component . Anticipating a response. Thanks in advance. Kind Regards, Muthu. lattice.stp
  6. Hello, I am trying to run topology optimization on rod elements. The optimization response would be buckling. I have two questions: 1) I am not clear about the upper and lower constraints for buckling response. Are they buckling load factors? What should I consider to define such constraint for buckling? 2) During the analysis and optimization, I am supposed to keep the length to diameter ratio greater than or equal to 10. How can I implement this as a constraint? Thank you in advance, Muge Candogan
  7. applying constraints in 3D mesh

    dear all, i have meshed a model with tetraelements and i want to constrain a structure at 3 top points where i want to have a pin joint.. i have created it as follows i created a rbe2 in the hole surface and at mid node i have applied constraint.. i.e i want to have a rotation along Y-axis here so i have constrained all five dof except 5.. and i am attaching my HM file with this kindly let me know whether what i have done is right or wrong? if it is wrong kindly let me know what is the right way to do it.. LG_mesh.hm
  8. Hi, After doing the HyperMesh morphing tutorials and the Optistruct shape optimization tutorials, I created a shape optimization file on my own. It consists of a cylindrical cantilever which is loaded sideways at the free end. The goal is to find an optimized cross section. The inner part remains unchanged, for the outer part (connected using equivalence) three different shapes are defined (elliptical morphing along x, along y and circular stretching). When minimizing the volume of the cantilever while limiting the stress in z-direction, the expected elliptical cross section results and the optimization constraint is fulfilled: Shape_opt_stress_constr.hm When limiting the displacement in load direction at the end of the cantilever, the cross section shrinks to a circle of minimum diameter and the displacement is much larger than the specified 0.15. Shape_opt_disp_constr.hm Isn't it possible to use displacement dconstraints for shape optimization? The solver (Optistruct) doesn't recognise the constraint violation and minimizes the volume to the extreme, leading to very high displacements. Thanks in advance for any inputs.
  9. Semi-Conflicting Constraints

    Hi, I'm working on a model that has two load cases acting on it with respective responses and constraints, one of them needs to have low deflection and isn't a problem, but the other needs to have deflection greater than X. meeting these 2 constraints in the free size optimization, while giving the solver a lot of freedom, isn't a problem. The problem is that I need the final layup/model to have no failure. so while the free size optimization thickens and focuses on bits to meet the first load case, I'm getting loads of failure due to the second. And because of what optistruct has done to the plies in the free size optimisation, I can't give it enough freedom to pass the sizing optimisation while meeting the failure constraint of 1 (tsai-wu) that I give it. I've tried varying my constraints in the free size to give it the opportunity to reinforce bits that might fail... Is there any sort of work-around at all to allow the free size optimization to constrain the failure? because this seems possible and would solve the problem. and if not, Is there a simple answer to why optistruct cant adhere to failure constraints in the free size optimisation? Thank you
  10. Constraints and BC in HM

    Dear all, I am a newbie in HW as well as HM and aim to setup a component and then perform the analysis with Optistruct. I have defined my BCs and constraints using RBE2 elements but face some issues. (HM model and image with BCs attached) I am not sure about how to define a displacement BC or Constraint on one of the holes (left end in the attached image). Aim is to constraint the sideway motion (x-axis) of the component to max of 2mm. I created a constraint load collector with load type SPCD and activated dof1 with a value of 2mm. Is this the correct way to implement the desired constraint? Secondly, I created linear static loadcases with option Load for my load collectors FRONT, CENTER, REAR and SPCD. Is it required to create a separate loadcase for Symmetry BC as well? I assume a (geom. non-linear) dynamic implicit type load step will be better to use in this case. But I am unsure which sub-option I have to use in that case. Some suggestions and recommendatiosn woudl be really helpful. I. Shaft.hm
  11. Weighted constraints

    Hi all, I am trying to do an optimization for a model with multiple load cases. For each load case a constraint is defined, but would it be possible to somehow use weighting factors for the constraints? In that way I hope some constraints will become more important to the optimization. Kind regards, Robbin
  12. Hi all, How can we select between coordinate system for assigning the constraints. i.e i have created a cylindrical co ordinate system by (1D---->System----->create) & assigned to the nodes to be constrained by (1D---->System----->assign)and i want to assign constraints to my component based on the cylindrical co-ord sys which i hav created but when i go to the constraints i can find only the DOF1 to 6 which was initially there and which denotes the global coordinate system and i couldnt find any place to switch over between the global and local coordinate system. Finding the place to change over between Global and Local coordinates in the constraints page will help me out from this problem. i have attached the constraints------>create, constraints------>update, but in both page i cant find any place to switch over to a local coordinate system awaiting reply .......... Regards Jeeva.B
  13. Hi, Does anyone have a good step by step method of combining multiple components and their loads? I understand the concept of first creating a 2-D shell and then a 3-D (for me, tetra) mesh to finalize a component. My specific problem is that I am trying to simulate fluid flowing through a solid (like a pipe of water through a cube). My partner does the CAD, and he gave me two IGES files of the components (one being fluid, the other being metal). The IGES files for both are just the "shell" surfaces for the two. I imported both geometries and began meshing. I created a 2-D mesh for the fluid, and one for the metal. Then I went to do tetramesh for each. I used the option "per-volume-component" to create a solid mesh for the fluid and the metal separately. If I wanted to specify a constraint on the fluid shell nodes but needed it to interact with the shell and solid elements of the metal...how would I go about that? Does it do it automatically? This is where I'm stuck, so if anyone has any advice or can direct me to some help, I'd really appreciate it! Thanks. Dylan Stelzer
  14. Loads and Constraints on Surfaces

    Hello community, I have a question concerning to apply loads and constraints on 3D surfaces. I have created a solid model from a 2D surface. If I do a 3D multi solid mesh and apply the constraints and the pressure onto the two surfaces (see figure 1), I will get a result. And I can see that every node on the surface is constrained and all elements on the surface are applied with a pressure force. If I create a 2D mesh first and drag the elements along the thickness of the model for a 3D mesh and then apply the constraints and pressure onto the surfaces, I will get no results. And further I can see that not all nodes on the surface are constrained and not all elements on the top surface are applied with a pressure force although I have selected the two surfaces (see figure 2). Why can't I apply the constraints and pressure on surfaces if I create a 3D mesh from a 2D mesh? And why is it possible if I mesh the model with the multi solid subpanel? Thanks in advance.
  15. loadstep

    Hi everyone, I am starting in HyperMesh and I have a doubt about the loadstep. In case you have more than one boundary condition (2 constraints or 2 forces), when you have to select in LOAD ( for example), the differents loads in the analisys I am not able to select all the loads. I can only select one load and I do not know the way to select all the different loads. I hope you have understood the question and you can help me. Thank you
  16. What is difference between Constraining nodes(directly from analysis->constraints) vs. rbe3? I am trying to do tensile test using Ls-dyna solver. Please post your comments.
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