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I want to model an ideal truss in ANSYS 2023 R2. The problem is that I don't know how to model the pin joints for the truss structure in ASYS APDL.

This is my question: A structure consists of beam CD and 3 links AC, BC and BD connected together by hinge joints at A, B, C, and D. Position B of the structure can slide on the inclined plane at an angle α relative to with the vertical direction. Dimensions and loads F acting on the structure (at center point of beam CD) is given in Figure 1. Bars and beams in the structure are fine made of material with an elastic modulus of E. The beam has a circular cross-section with diameter ϕ. The bars have cross-sectional area A.

  • h = 1.4 meters,
  • l = 1.1 meters,
  • F = 190000 N,
  • a = 19
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  • $\begingroup$ For a start, assume beam CD rigid and find forces by hand calculations in the links with a good degree of approximation. . Analyze CD separately. $\endgroup$
    – Narasimham
    Dec 3, 2023 at 20:19

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LINKs + BEAMs

You can model trusses in classic Mechanical APDL interface using LINK elements. C-F-D still needs to be modelled with BEAM elements. You will also need to fix DOFs so the model remains in 2D plane (UZ, ROTXZ, ROTYZ if the model is in XY). And also fix remaining rotations for nodes where only trusses meet. Inclined sliding support at B is a little bit tricky, you need to rotate coordinate system of corresponding node (NROTA command) into prepared rotated coordinate system (best to use Workplane here).

BEAMs only

Another possibility is to use only BEAM elements, however, they cannot have shared topology at the ends (so the rotations are not coupled). Then you need to couple just displacement DOFs there (using constraint equations or joints). This option would probably be best for (Workbench) Mechanical, where LINK elements may not be available.

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  • $\begingroup$ just using link elements? When I use both links and beams, Ansys cannot solve my problem $\endgroup$
    – Joon
    Dec 2, 2023 at 14:50
  • $\begingroup$ Just LINKs is the best option. I mentioned beams only because Workbench Mechanical will probably force you to use beams. What is the error you are getting when you start the solution? $\endgroup$ Dec 2, 2023 at 17:15

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