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  1. MOZER8

    Truss and Beam element axial loading - stress difference

    I found the solution in updating the stress-strain table in hyperelastic material properties. By doing so, stress values will neglect the cross-section updating effect. It require some hand calculations which can be achieved by excel easly.
  2. MOZER8

    Truss and Beam element axial loading - stress difference

    FEA way, thank you for your reply. I missed the part about truss element that their cross-sections are calculated with the assumption of they are incompressible.
  3. MOZER8

    Truss and Beam element axial loading - stress difference

    This one is just a dummy model to test element behavior. I won't be able to lower the force since the force is applied from a accelerated mass (you can check my previous post about ball catch analysis with a net). Beside from that, since the material is nonlinear, lowering force will not give...
  4. MOZER8

    Truss and Beam element axial loading - stress difference

    I had another idea: I set the poisson's ratio to zero in order to prevent cross-section shrinkage? However results are still not logical. Any idea?
  5. MOZER8

    Truss and Beam element axial loading - stress difference

    That explains it. Is it possible to turn off cross-section update during the analysis. Because I have force - strain data, and I converted it into stress-strain assuming the cross-section is constant during the analysis.
  6. MOZER8

    Truss and Beam element axial loading - stress difference

    Hello All, I have a problem. I made a very simple simulation to test the 1D element performances. One has been built with beam elements, other has been built with truss elements. All other properties are the same. Both are under tensile loading, nlgeam is on since the material is nonlinear...
  7. MOZER8

    No compression 1d elements in abaqus explicit

    FEA way, The purpose of the analysis is to simulate to pull a 20kg sack with a van. Mass is connected to rope, rope is connected hyperelastic spring, spring is connected to loadcell, loadcell is connected van. Rope is long enough to let the van to reach 25m/s before it pulls the rope. (It is...
  8. MOZER8

    No compression 1d elements in abaqus explicit

    Hello All, I want to use no compression 1d elements in abaqus explicit (elements like nastran gap elements). I used hyperelastic material with negative strain and force but it gave unrealistic results. Basically, I want to model model a mass spring system. The spring has nonlinear stiffness...
  9. MOZER8

    Hyperelastic net under gravitational load

    First, I was running it from CAE. After I switched to command lin, it realized it can't find .res file from previous analysis. It seems I forgot to turn the restart on. It is running without a problem now. Thank you for your support again. For others who check this topic later. Frequency was...
  10. MOZER8

    Hyperelastic net under gravitational load

    FEA way, Erik, Thank you very much for the support again. I have completed the first analysis with your support. Now I need to inport these analysis results into an explicit dynamic analysis as a initial contidions. So I select initial state from predefined field menu. This gave me the...
  11. MOZER8

    Hyperelastic net under gravitational load

    Pretension for initial conditions solved my problem. Thank you for your help.
  12. MOZER8

    Hyperelastic net under gravitational load

    Thank you for the suggestion. The thing is, two different material is used in this net assembly. Inner net is hyperelastic material with very small stiffness. On the other hand, frame is made of steel (relatively high stiffness). Thus if I apply large displacement, experience high stress values...
  13. MOZER8

    Hyperelastic net under gravitational load

    Hello Everyone, I have modelled a net with following parameters: Net elements: Truss(T3D2) - hyperleastic Frame: Beam(B31) - linear elastic BC: constraint: DispXYZ=0 at two side of the frames load: 1G gravity which is normal to net Step: General static, nlgeom=on It is a pretty straight...
  14. MOZER8

    Abaqus B31 elements Excessive rotation error in explicit dynamics

    Erik, FEA way, Thank you very much for your help and support. I have fixed the model, element deletion is working, but I'm not sure if the modeling or parameters are all correct. I will make some research about the damage theories in abaqus. In summary: truss elements, linear elastic material...
  15. MOZER8

    Abaqus B31 elements Excessive rotation error in explicit dynamics

    Okay, now I converted web material to linear elastic with an acceptable error. Then I tried to run it with truss elements it didn't allow me to set fail strain or fail stress criteria, thus I cconverted the elements to beam elements. In summary, beam elements, linear elastic material with fail...
  16. MOZER8

    Abaqus B31 elements Excessive rotation error in explicit dynamics

    Erik, FEA way,thank you for your interest to this topic. I added "*SECTION CONTROLS, ELEMENT DELETION=YES" to input file even thought there is no element deletion option under truss element in GUI. In addition to that, I need an damage evaluation for my material. However, Stress fail and...
  17. MOZER8

    Abaqus B31 elements Excessive rotation error in explicit dynamics

    Thank you for the suggestion. It seems truss element solved my issue. Now I need some damage criteria and element deletion for truss elements. Can I apply element deletion criteria for truss elements?
  18. MOZER8

    Abaqus B31 elements Excessive rotation error in explicit dynamics

    Dear All, I am doing a web catch analysis using abaqus dynamic explicit. An object with initial speed of ~50000mm/s is cought by a web which is built with B31 elements. B31 elements has hyperelastic properties. Contact between object and web was defined as general contact. Analysis duration is...
  19. MOZER8

    Nastran sol 129 non-linear transient analysis - Gap element usage

    dfreire, -Thank you for the suggestion. First of all, I changed the output request to .op2. This solved the missing element results issue. -As you mentioned, I removed G damping used MATi and PARAM,W4 instead. While defining G damping, my intension was to provide stability to gap elements...
  20. MOZER8

    Nastran sol 129 non-linear transient analysis - Gap element usage

    Thank you for the prompt answer Erik. After you mentioned I checked the .bdf file, because I remember that the initial gap was set to 2mm. Nastran uses 8 digit system in bdf input files. Thus it is not 22.0, it is 2 and 2.0. First 2 indicates to pgap ID and second 2.0 indicates initial gap...

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