2D Axisymmetric Analysis with LISA
2D Axisymmetric Analysis with LISA
(OP)
I am new here. I hope this isn't too simple a question for you guys.
I am evaluating the LISA FEA package. I am trying to get the "textbook" results to verify I am using the software correctly. I have come across a strange problem. I am doing a 2D axisymmetric analysis. It is just a solid ring with an ID and OD. I am setting a "weight" in top of it with the force evenly distributed across the face of the ring. So I am doing this by just drawing a x-section (a rectangle) in the X-Y axis that represents the ID, OD, and height of the ring. I adjusted the ID and OD to make the area 1 sq.in. I constrain the bottom row of nodes to have no displacement in the Y direction. When I put a pressure on the top face of 500psi, I get the expected 500psi of von-Misses stress in the ring. But when I put a 500lb force on the top row of nodes, strangely I get 125psi of von-MIsses stress everywhere in the ring x-section. Does anyone know why this is happening. I have the feeling it has something to do with my lack of understand of how to apply forces in this type of analysis. Thanks in advance for any help you can give.
I am evaluating the LISA FEA package. I am trying to get the "textbook" results to verify I am using the software correctly. I have come across a strange problem. I am doing a 2D axisymmetric analysis. It is just a solid ring with an ID and OD. I am setting a "weight" in top of it with the force evenly distributed across the face of the ring. So I am doing this by just drawing a x-section (a rectangle) in the X-Y axis that represents the ID, OD, and height of the ring. I adjusted the ID and OD to make the area 1 sq.in. I constrain the bottom row of nodes to have no displacement in the Y direction. When I put a pressure on the top face of 500psi, I get the expected 500psi of von-Misses stress in the ring. But when I put a 500lb force on the top row of nodes, strangely I get 125psi of von-MIsses stress everywhere in the ring x-section. Does anyone know why this is happening. I have the feeling it has something to do with my lack of understand of how to apply forces in this type of analysis. Thanks in advance for any help you can give.





RE: 2D Axisymmetric Analysis with LISA
RE: 2D Axisymmetric Analysis with LISA
It is an axisymmetric analysis - with Y axis symmetry. The bottom nodes are constrained to 0 displacement in Y. The top nodes have a 500lb force on them.
So, since it is axisymmetric, a rectangle drawn like I have it, should represent a solid ring with rectangular x-section.
RE: 2D Axisymmetric Analysis with LISA
RE: 2D Axisymmetric Analysis with LISA
RE: 2D Axisymmetric Analysis with LISA
RE: 2D Axisymmetric Analysis with LISA
RE: 2D Axisymmetric Analysis with LISA
RE: 2D Axisymmetric Analysis with LISA
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RE: 2D Axisymmetric Analysis with LISA
RE: 2D Axisymmetric Analysis with LISA
In addition, as rothers says, some packages ask for the load per circumference (N/mm), or radian, or the total load (N). It's worth checking the manual and results to see what the package does when applying loads and calculating reaction forces.