LS Dyna

LS Dyna

Pressure load is exerted in the x-direction instead of on the normal axis (LS-DYNA) ?

    • LCP
      Subscriber

      Hello,

      I am simulating a hyperelastic stick with a pressure load exerted on the side of the stick. I assumed this load would be applied on the normal (just like in the first picture) for the entire simulation, but it seems that it is exerted in the x-direction instead. I have checked this using ANSYS Mechanical, where I know for certain the pressure is exerted on the normal axis. The difference between the two results is shown in the second picture. When changing the pressure load to x-direction in ANSYS Mechanical, the result resembles the LS-DYNA result closely. So how do I check how the pressure load is exerted in LS-DYNA, and how do I make sure it is exerted in the normal direction?

      Kind regards,

    • Akshay Maniyar
      Ansys Employee

      Can you share some more details about the model? Is it a shell mesh?
      Which card you are using to apply load?
      regards amaniyar
    • LCP
      Subscriber

      For the LS-DYNA mesh: I am using shell elements (8SECTION_SHELL -> option plane strain). This means I am essentially modeling 2D solid elements. I create create a segment set by selecting the edge and clicking propagate. Then, I apply the load via *LOAD_SEGMENT_ID. I also applied *HOURGLASS type 7. I do not know if this is necessary, though.
      For the ANSYS Mechanical mesh: I am using PLANE182 elements with a plane strain assumption.
      I already found out that LS-DYNA does exert the pressure on the normal axis, since the tip of the valve cannot be lower than the middle of the valve if it was exerted in the x-direction. The weird thing is, when I run the simulations in ANSYS Mechanical 2021R1 the displacement does coincide with LS-DYNA, but when I use ANSYS Mechanical R19.2, the deformation is much larger than LS-DYNA. Do you know why this is the case?
    • Akshay Maniyar
      Ansys Employee
      Hi @LCP I am not sure exactly why you are getting difference in the results for 19.2 and 2020R1. Can you create a new post for this query as the original question was for LS-Dyna. May be some structures expert can answer this. I will also check mean while.
      regards amaniyar
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