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Staedtlerp

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  1. Hi @Koushik Chandrashekhar, thank you very much for your prompt reply. I've looked for the MATCHECK parameter in the PARAM control cards but I haven't found it. I tried even by search command (CTRL+F) but It doesn't appear in the search result list. Maybe it is the version of the software I work with (I have got the 2017.2 version). I have found in the PARAM control card the parameter CHECKMAT..Is it the same?? Thank you
  2. Hi everybody, I want to perform a non-linear structural analysis of a sandwich panel. As stated by the title of this topic, I modelled the sandwich panel by using 2D shell elements for upper and lower skin, and 3D solid elements for honeycomb core (I have created the 3D solid elements by using solidmap/linear solid command and matching elements of upper and lower skin). The panel has been loaded with a centrifugal force using RFORCE, trying to simulate the centrifugal force of a rotor (the panel I modelled is located at the tip of that rotor). Being the panel subjected to inertial force, I decided to use the Inertia Relief (activating it on PARAM with value -1) and adding Support1 constraints. The question (the issue) is the sequent: Upper and lower skin plies have been modelled using 2D elements, MAT8 as material, and PCOMPP property. To model the core, I decided to use 3D elements, MAT9ORT as material card and PSOLID as property. Looking at the online help, MAT9ORT "Defines the material properties for linear, temperature-independent, and orthotropic materials for solid elements in terms of engineering constants", so I decided it was suitable for my aim. To fill in engineering constants, I have used values coming from HEXCEL datasheet (Aramid Fibre/Phenolic Honeycomb), considering 1 directions as the Y direction of the AxysSystem, 2 direction as the X direction of the AxysSystem and 3 as the Z direction. Following the used properties: E1=E2=0.01 (very small according to HEXCEL guidance material) E3=138 MPa (HEXCEL material properties) mu12=mu13=mu23=0.01 (very small according to HEXCEL guidance material) G12=0.01 (very small according to HEXCEL guidance material) G13=45MPa HEXCEL material properties) G23=23MPa HEXCEL material properties) As long as I start the analysis, I get the following message: A fatal error has been detected during input processing: *** ERROR # 1551 *** for material id = 2 referenced from property id = 4. Material coefficients Gij on MAT9 card produce material matrix with negative eigenvalues. This violates material stability conditions. Eigenvalues of G: 1.010049e-002 9.900507e-003 -3.630604e+002 1.000000e-002 2.300000e+001 4.500000e+001 *** Run terminated because of error(s) in the input data. I don't know exactly what It means.... I suppose is something related to the material card... But the stranger thing is that changing the E3 value from 138 MPa to 0.138 MPa it works... I'm completely confused Does anyone know the reason why It behaves that way?? Is correct to use MAT9ORT to simulate 3D honeycomb? Tip.hm Thanks in advance Attached you can find the model. Thank you
  3. Thank you very much @Adriano A. Koga for this explanation, it is very helpful. I've never used these type of contact (finite or continuos sliding) before; I've never had to use it because my simulations involve essentialy small sliding between parts. I believe it will be very helpful for me in the future. Thanks a lot
  4. Thank you very much @Adriano A. Koga I think I have sorted out the problem. The main problem was related to the PARAM/EXPERTNL/CNTSTB bulk data; it was not activated. Then, I looked for a solution on this forum and I find something similar to the issue I encountered. Now It goes straight with no problems. What do you mean with FINITE SLIDING?? is it mandatory to activate it for LGDISP analysis?? Thank you very much Furthermore, I'm not able to understand what are Non_EUI_st, GapClose_st, etc.. yet. I don't find anything in the online guide. Could anyone explain this? Thank you.
  5. Good evening all, I have tried to perform a structural analysis involving a pin and a slot. I have set up a Non Linear analysis with contact using small displacement (NLPARM). At the beginning the pin is not touching the slot, then It touches the slot and the contact start working. On the pin acts a LOADADD force (Fx+Fz), the other dof are blocked (rotations and traslation along y). Otherwise the slot is fixed (only traslations, no rotations because I think is unuseful). Attached you can find the model (Hypermesh 2017.2 model). I have set up a contact with a property type SLIDE and Discret N2S. Furthermore I have chosen the pin as master and the slot as slave. The problem is that after a bit it comes up with a result message (analysis completed), but it seems It hasn't performed all the increments I have set up. I think the results have not any sense. Could you please take a look at the model? Is that solution correct?? Furthermore, there is attached a screenshot of the run panel of Optistuct. In the upper right corner threre are the Iterations column and the Subcase column. I'm not able to understand why the Iteration or Subcase are not matching the number of increments I have set up (30). What are Non_EUI_st, GapClose_st, etc..?? Do I need to change contact parameters adding, for example, a contact property? Many thanks you very much for the your help and time Interfaces_single_harness_attachment_interface_contact_NonLinear.hm
  6. Hi guys, thank very much for your replies. I read the post from @Koushik Chandrashekhar but i didn't understand how to display mass values. Then I read the post from @Mario and I think It could be a great advice to recap mass values when using CONM2 elements. So, thank you very much to all. Is there anyone with other advices?
  7. Hi all guys, I'm modelling a platform with different devices linked to it. I modelled the devices as concentrated masses linked to platform with rbe2 elements. The problem is that, activating Display Element Handles, I can see the element type name (CONM2) but I can't see the mass value of each mass. Is there a way to display, along with the element type name, the associated mass value?? Thank you so much
  8. Thank you very much @Rahul R for your prompt reply and for the document. As far as I understand, selecting Composite Failure as result type the program allows you to check for the failure index of each ply or bond (infact It allows you to select, in the second drop-down menù, between Ply Failure and Bond Failure), instead, selecting Composite Failure Index as result type, the program allows you to check for the failure of the overall laminate (selecting the worst failure index across all plies and bonding layers). The laminate will fail if at least one ply fails. However, I don't understand why, selecting Composite Failure Index as result type, in the second drop down menù I can choose between Failure Index and Ply with Maximum FI. What does it means the second option? I can verify each ply failure index by selecting Composite failure as result type in the first drop-down menù. Is there any difference? Furthermore, by selecting Ply with Maximum FI in the second drop-down menù, I receive a numeric value very different from the Failure index of each ply? For example, in a simple problem I'm working on, the max failure index is 0.8 but, selecting Ply with Maximum FI, I receive a max value of 13. What does it means? Thank you very much
  9. Good morning all, I have a question about the visualization of results in a composite analysis. I performed a structural composite analysis and then I entered the Hyperview workbench in order to show results. In the result type I can choose between different options (composite stresses etc) and I found that Composite Failure and Composite Failure Index results are available. I don't understand the difference between these two options. Furthermore, a second drop down menù is willing under the first (see picture). If a choose Composite Failure, in the second drop-down menù I can choose between Ply Failure and Bond Failure, if I choose Composite Failure Index in the first menù I can choose between Failure Index and Ply(s) with Maximum FI in the second drop-down menù. Could somenone help me to understand? Does anyone know where to find the explanantion of all result types in the documentation? Thank you very much.
  10. Prakash Pagadala thank you so much Probably I made a mistake reading and studying the tutorial, but It is better to control to avoid misunderstandings
  11. @Q.Nguyen-Dai perfect and clear! thank you so much. I guess it could be a mistake in the tutorial that I mentioned. Thank you very much
  12. Prakash Pagadala Thank you very much. I think I'll do in this way, selecting the surface at which elements are associated. But I have a question: on the tutorial "Composite optimization of a skateboard with Optistruct", pag. 13, how are calculated pressures? It seems that the pressure is divided by the total number of elements.
  13. Sorry I couldn't be able to delete the tag...so, how is it the correct way to calculate pressure on each element? Thank you
  14. Hi Prakash, I have a question. Considering I have 100Kg applied on a surface of 1m^2. I have a pressure of 100 kg/m^2=981N/m^2=9,81*10^-4 MPa. The total number of elements is 200 so each one is 5mm^2. Why have I to divide the total pressure by the total number of elements?? To obtain the pressure on each element I guess I have to multiply the pressure (9,81*10^4 MPa) to the area of each element. Or not? Sorry I'm quite confused, I don't understand why I have to divide the pressure by the total number of elements. thank you.
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