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matej

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About matej

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    Slovenia
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  1. I am using Optistruct 2017.2.2 and just tried with S2S contact and I get much better results. They are still about 40% higher from analytical values; however, this might be due to quite coarse mesh I am using right now. Additionally, also the contact forces are for about the same factor lower than before, which gives much more logical results. Thanks a lot for your help! Anyway, what is the difference between the Contact Traction and the Contact Stress (Pressure option)? Because the results differ a bit (even when observing corner data for stress).
  2. Hello, I have performed a simple non-linear quasi static analysis to study a ball-plate contact. Optistruct was used as a solver. Contact is modelled as node to surface, slide contact. I am wondering why Contact Traction (Normal) is resulting in a very high number? As far as I understand, Contact Traction (Normal) is supposed to represent a pressure in a contact. In such a simple example (ball-plate contact) it is easy to verify the results with analytics, which in fact yields more than 100 times smaller values for the contact pressure in comparison to the Contact Traction results. As a "workaround" to plot the contact pressure, I am checking Element Stresses, where the option Pressure is chosen (I have CONTF card enabled in a solver). The results are correct here. Could you please give me more insight of what Contact Traction is representing? I haven't found anything in a Reference guides. Thank you in advance, Matej
  3. But is it possible then to change the contact type during load steps in Optistruct?
  4. Hi Prakash, could you please provide any additional explanation why a contact type should not be changed when using CNTNLSUB?
  5. Hello, I have set a Nonlinear quasi static analysis (type NLSTAT) with two consequent load steps (using CNTNLSUB option). In my model two parts are gradually getting in contact (something similar as roller - plane contact), where also friction is taken into account. In the first step a radial force is pushing the roller towards the plane and in the second step additional lateral force is applied. Everything works fine, the results seem meaningful. Now I would like to set a first load step with contact type SLIDE and the second (continuous) load step with friction in contact. Is this possible in Optistruct? Thanks for your help! Best regards, Matej
  6. Hello, I would like to calculate a contact between a sphere and flat solid block, pressed together under certain load. I am interested in the contact stress and precise contact area (I would like to compare the results with the analytical solution of Hertzian contact theory). Is it feasible to get the desired results with a non-linear quasi static analysis in Optistruct or shall I do it with Radioss? Additionally, what is the best way to obtain the final nodes in contact or even to fix them together and perform an additional analysis? Thank you for you help, Matej
  7. Well, it is not directly connected with a specific type of analysis. I am just trying to understand the basics. Which property card changes integration points in Radioss? Is it also available in Optistruct? Best regards, Matej
  8. Can you please be more specific. How to view or load the mass and stiffness matrices, based on the op2 files in HV? Greetings, Matej
  9. I am using Optistruct.
  10. Hello, for a certain element type in Hypermesh I am able to switch between 1st and 2nd order. Is it possible to set also reduced integration for a chosen element, or to prescribe the location of the integration points? Thanks for all information, Matej
  11. Hi, I am facing the same problem. The method for calculating the .k.op2 and .m.op2 files seems the most straightforward to me. But how can I read obtained binary files? Thanks for you help, Matej
  12. Hello, I am calculating simple static analysis (have a 3D mesh) and investigating the strain on the surface. I am wondering if there is an option to plot the "corner data" for strain. I am often using an option in the global_output_request -> stress -> location: corner which enables me to plot the "corner data" for the stress in HyperView. However, the strain tab in the global_output_request does not contain the "location" property. Currently I get the proper strain on the surface simply by reading the right stress on the surface and dividing it with elastic modulus. Thanks in advance for any help or. comment. Matej
  13. I pick the "build graphs" botton. For "X type" I choose Frequency, for "Y type" acceleration. Then I have to choose "Y request", which is the node where I want to investigate the acceleration. Further, the "Y component" has to be defined. Magnitude and phase in all three direction are available. What I am asking is, how to define "Y component" in different direction than just X, Y and Z. I would like to have the component perpendicular to the surface of my part, since the acceleration is the maximum there.
  14. Hello together, I am calculating modal frequency response analysis. At the end I would like to plot FRFs, i.e., the acceleration with respect to the applied force. When defining the direction of the acceleration, I can use just magnitude in the x, y or z. How can I define my own direction? Thank you for your help! Matej
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