APDL 2 Quadrilateral elements

I have a plate formed of two rectangles and I want to create 2 quadrilateral elements only for the whole plate and the element type is 4 noded quadrilateral. I tried different ways in APDL to control element number but couldn't so can someone help to create only 2 quadrilateral elements for the plate.


  • peteroznewmanpeteroznewman Member
    edited December 2020

    @shehab Gamrah

    Three quad elements would most easily mesh that L-shaped surface. Add one node on the 1-2 edge of E1 below node #7. Then you will have a square element in the corner and two rectangular elements.

    If you must have exactly 2 elements, then delete node #4 and the two elements will share an edge between nodes 1 and 7, but the element shape will be of poor quality.

  • Thanks for reply. The problem is I must have two quadrilateral elements of equal size, hence I would want to have one quadrilateral element formed by nodes 1-2-3-4 and another one formed by 4-5-6-7 so I was wondering how can I do that in APDL. Moreover if I delete node 4 it would be trapezodial element not quadrilateral.

  • @shehab Gamrah

    If you use the 2 elements you describe, there will be no connection at node 7 to Element 1. That means Element 1 and Element 2 will only be connected at node 4. This will make a hinge. That is why I wrote the two solutions that keep the L-shaped bracket as a continuum: one with two trapezoidal elements or one with three rectangular elements.

  • Thanks alot, just two questions

    1) If I model it as the two equal quadrilateral elements, is there a way to overcome the hinge problem, as the solver gives me error unconstrained model.

    2) does trapezodial element have same shape function of the quadrilateral element

  • @shehab Gamrah

    1) Not without introducing another element. The simplest solution is to use 3 elements.

    2) Shape functions work for any element shape including trapezoidal.

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