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Keonkim1991

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Everything posted by Keonkim1991

  1. Thank you Andy it worked!
  2. Dear, In my T01 file, I only have Global Variables entity. What I actually need is Node/Disp and RwallForce entities for my force/displacement plot. Is there any control card settings to request these entities? I have been looking into other tutorials but it seems like all these entities should be automatically requested? There's only Global Variables in my T01 file.. How it should show.. Thank you, Ken
  3. I'm trying to clean and delete all the unused input data for my GFEM model. It has been passed around different people and there are thousands of data being unused mainly in HyperBeam section. what would be the best way to delete all the unused cross section entities without checking individual components manually?
  4. In the HyperView, is there any way I can export the stress result contours to as a step file for color indications? I need this for my further topology optimization study..
  5. Hi Prakash, please share the example files with me. It's a bit hard to follow the document itself.
  6. Hi Prakash, did you mean to attach a link or pdf file? I'm not sure where I can find the periodic boundary conditions examples in Optistruct. Please help.
  7. Is there any example of periodic boundary condition for a cubic (Unit Cell)? As an example, bottom plane is fixed whereas top plane is -1% displacement, and result stress contours can be predicted for mesh or macro structures.
  8. High Prakash, Sorry for late reply. What do you mean by design and non-design space? My model is consist of 1D elements (PBEAM) with the cross section area (BOX: 50.8 x 25.4 x 5.0 x 5.0 mm). I have optimization responses of total mass, total displacement, and static stress. Displacement and stress were constrainted under the objective of minimizing the mass.
  9. I found out that my BCs are wrong for unit cell compression. With this BCs below, the high stress in the corner of cube was eliminated and the structure uniformly deformed as I allowed free translation on the side edges. Thank you for your help.
  10. Good morning Premanand, Thank you for your reference for the node connectivity. I used PSOLID for all properties as the model was 3d-tetrameshed. For materials, Carbon Fiber: E = 231000 MPa, NU = 0.2, RHO = 1.76e-009 & Epoxy: E = 3425 MPa, NU: 0.32, RHO: 1.25e-009. But please note that, due to this study includes dummy load for only convergence study, the geometry scale was left as default (milimeter) when it should be micrometer in reality scenario. So stress result values itself are not correct, but this is to only investigate the stress transfer between elements from different solids. And to help you understand more details, below is my BCs. 1. Top plane (RBE - compression load in -x axis on an independent node) 2. Bottom plane (SPC constraints - all nodes on the bottom plane) Thank you for your help.
  11. Thank you Prakash. Please let me know. Have a great week.
  12. In addition, I ran a dummy analysis to study mesh convergence. As you can see below, significant changes in stress between elements from matrix to carbon fiber can be seen below (1.5 MPa to 240.4 MPa from blue to red element). Shouldn't it change smoothly? Not like this crazy changes. This is my initial run so mesh is real fine, so I don't believe it's due to element quality errors. Also, I made sure all the nodes were connected and all the duplicated nodes were assigned for equivalent. Not sure why it's like this? My BCs are pretty simple: Top plane (RBE - compression load in -x axis on an independent node) and bottom plane (SPC constraints). Please help me understanding this drastic stress transfer.
  13. Hi Premanand, You sir are the best. Thank you very much. I was able to create mesh on the circles both sides like below. And then I copied the inner cylinder part of the matrix, copy the elements on that surface and assign it to the carbon fiber as below. I made sure they share same nodes as well (In the end I made them equivalent). Later on I was able to assign the tetramesh on the part (masked view). So I believe I was able to connect the nodes from one solid (matrix) to another (carbon fiber). But for last clarification, all the unit cell study has to have the node connection between different solids? Is it always the case? Please help me understanding.. Have a great weekend and hope to talk with you on Monday.
  14. I'm currently trying an imprint option that I can select the source/destination. I've tried source as the blue circles, destination as the grey, and remain the destination, also vice versa. But it's giving me an error of Input elements must be of the same order. What does this mean? And how can I proceed this method? Or is there any other more efficient ways?
  15. Hi Premanand, Yes I've tried the equilvalent option, and I was only able to connect very few nodes due to the meshes from different solids are not referenced each other. Please excuse me I can't upload the model due to company's confidentiality.. What do you mean by projecting the grey elements to the inner blue surface? Can I somehow extend the grey mesh into the geometry of the blue circle? Please give me more details...
  16. it's 100% beam elements with 1 RBE3 element that was used for attached object's CG where assign axial load. Below figure is a contour plot for element stresses (1D) (CBAR/CBEAM Axial Stress). It's within the criteria I've assigned, but still, way too low (tension = 40.1 MPa, compression = 98.8 MPa). I understand displacement response/variables play a role to determine the stress results. But I want it to be as close as possible to my criteria (tension = 289.6 MPa, compression = -234.4 MPa).
  17. I'm currently working on a unit cell study (carbon fiber + matrix + additives). I thought it would be very easy to mesh it out and run my test, but I've been spending too much time in determining good quality of mesh. I have 3 components (3 different solids) that need to be meshed. I was able to successfully tetra-mesh individual solids with curvature and proximity, but couldn't find the way to somehow connect them. I tried to re-mesh multiple times with 2D automesh to tetra mesh technique, translating surface meshes to another, assigning equivelent on the duplicated nodes, etc. But frankly, it's too time consuming to accomplish good quality mesh, and I can't spend more time in this part. Later on I found the contact surface method preventing the penetration between parts by assigning slave and master BCs on shared surfaces (i.e. outter surface of carbon fiber and inner surface of matrix). Please give me some advice whether node connectivity can be replaced by assigning contact surface. My one concern is that later on I'll have to check the carbon fiber penetration in a reality scenario, and this method won't work for that due to the slave/matster bounded condition. If node connectivity must be properly done (which I assume..), please provide me some type of tutorials that present about connecting "multiple solids". I've went thru lot of meshing tutorials but only found the ones for single component/part or simple geometry setup that can be easily automeshed/translated/rotated.. Figure displays the carbon fiber (purple) and matrix (gray) nodes are not connected. Figure 2 displays the contact surface BCs applied on the shared surfaces of carbon fiber and matrix. Please excuse that I am not allowed to upload the model.. Your help would be really appreciated.
  18. Hi Prakash, I'm not allowed to distribute any of my files due to company's confidentiality. I know the definition of CBAR/CBEAM axial stress, but my question is to know how to properly assign optimization response/constraint for this matter, just like how I was able to optimize the minimized mass with the displacement criteria. Below are optimization reponse and constrain that I've assigned to the model.
  19. My model is a simple 1D PBEAML element structure (BOX beam sections) assigned for linear static analysis. I was able to assign design variables and property relationships for beam thickness 1 & 2. Then I assigned the optimization response for all nodes and constrainted them by lower/upper bounds ±25.4 mm under the objective of minimizing mass. With these steps, I was able to reduce the weight of the structure as well as meeting my displacement design criteria as closest as possible. However, the issue is now the stress increased beyond the yield strength. So I went back to my model and added the optimization reponse for static stress for all properties and constrained them with lower/upper bounds -234.4 MPa and 289.6 MPa (compressive and tensile yield strength). I made sure the response and loadsteps are assigned to the optimization constrain properly. After running the optimization, I checked the results in Hyperview, but it doesn't seem like the stress part hasn't been assigned correctly. I'm specifically looking for constrainting Element Stresses (1D) (s) - CBAR/CBEAM Axial Stress. It seems like there are other types of stress you can assign besides the static stress, such as frf stress and psd stress? Please help me.
  20. Hello, I have a model that has already solved for stress/displacement analysis. Now, I have particular spots to look into more closely. I know there is a group feature that allows element grouping, but with this feature, can I see the assigned group and the results (particular elements in my structure) in hyperview? I'd like to set those particular elements and see how the stresses change as I make structural modifications.. If so, please tell me how to apply this. Thank you.
  21. One more question, I have nano components inside of the composite structure and want it to be interacted by the compression force that's applied on the top surface of the structure. Right now the nano components don't get any reactions due to unassigned boundary conditions. Here I'm looking for what kind of BC I should make on the nano components that can be connected to the matrix structure in the compression scenario? Should I combine all the components as one solid? Please provide me suggestions..
  22. Oh it worked, but shouldn't composite materials always be assigned as MAT8? Is it because of the case I'm approaching it with 3D meshing, so I must apply MAT1 in order to define PSOLID elements?
  23. Okay I just did, but I still get this error message, *** ERROR # 78 *** MAT8 data can only be referenced by PSHELL data. This error is for MAT8 # 1, referenced by property # 1. ************************************************************************ A fatal error has been detected during input processing: *** ERROR # 78 *** MAT8 data can only be referenced by PSHELL data. This error is for MAT8 # 1, referenced by property # 1. ************************************************************************ ==== End of solver screen output ==== ==== Job completed ====
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