LS Dyna

LS Dyna

Topics relate to LS-DYNA, Autodyn, Explicit STR and more


    • umad

      HELLO everyone.

      I am modelling masonry wall in LS DYNA. Airbags (inflate and deflect) were used to apply the displacement out-of-plane loading on the wall in a semi-cyclic manner. I have recently been trying to replicate the experiment setup using the LS DYNA, as shown in the image; however, I am having difficulty applying the loading protocol. I do not know which LS DYNA keyword to use for the application of the out-of-plane loading protocol. The airbags, when inflated, provide a spatially uniformly distributed loading on the wall. I know that the loading protocol can be applied using the BOUNDARY_PRESCRIBED_MOTION keyword for the In-plane loading simulation. I would be glad to know the LS DYNA keywords or methods to apply the loading successfully?

    • Aniket
      Ansys Employee
      Ansys staff can not download any files on the forum, so if you want to reach a larger audience to get answers from, please insert inline images describing your problem.
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    • umad
      Dear Aniket Thanks for the information and the links.
      Here is the image of the experiment(cavity wall) and LS dyna simulation (of single wall) under monotonic loading (I used LOAD_SEGMENT_SET keyword to apply the lateral load). I want to know how I can apply cyclic loading (displacement) on the wall in the same manner.

    • Andreas Koutras
      Ansys Employee
      have you used cohesive elements or tiebreak contact for modeling the horizontal mortar joints ? If not, I think you should do so. In that case, the closest way I can think of is to prescribe equal displacement at the nodes that are right above and right below the mid-height (assuming symmetry). BOUNDARY_PRESCRIBED_MOTION can be used to apply the displacement. You may also need to use a finer mesh through the wall thickness to better capture the out-of-plane behavior.
    • umad
      Thanks for the feedback.
      I used Contact _ Automatic_Surface_Surface_Tiebreak to model the mortar joints.
      I will do as you advised.
    • umad
      Hello everyone.
      I am doing simulation of Rigid body analysis of masonry wall in LS DYNA and needs help on how to improve the numerical simulation.
      Wall dimensions: Height of the wall is 4.1m, Length is 1.15m, thickness is 0.35m. During the experiment, the crack height from the base of the wall is 2.501 m.i.e height of bottom wall is 2.501 m and height of top wall is 1.599
      Contact Automatic Surface to Surface was used in a between the two walls interface and between the floor and bottom wall interface. Friction coefficient of 0.7was used.
      Contact Automatic Surface to Surface was used in a between the top wall and top support. Zero friction was used here.
      Uniformly distributed load was assigned on the wall face.
      Material model: Top support and Floor (MAT_001) and assigned to Young modulus Elasticity of 40000 MPa
      Two block walls (MAT_020) and assigned to masonry Young modulus of 4758 MPa
      Numerical resultis not matching with the hand calculation (Rigid body Analysis)

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