addition of knots on a modeled structure

[Dare1989]

Good morning to all,

I am modeling a shell structure, using as shell181 elements. This structure is divided into several areas as some areas need to be thicker due to increased stress. In addition to its own weight and snow load, I must add horizontal forces that represent the wind and that I must place on the edges of the structure. These horizontal forces are arranged at a distance of one meter and depend on the height of the point of application.

My problem is that in ansys I have to apply a force on a knot and I cannot apply it at any point by simply defining the coordinates. Then I thought I'd create keypoints so I could apply our forces. only that when I make the mesh these keypoints are not recognized as they are not necessary for the creation of structure geometry, but they are only there to be able to apply forces. if I create the knots by giving them coordinates of the points to which to multiply these forces, they are not then recognized in the mesh, and an error message of the type "force load on unused node 11 fy. "

My question is: is there a way to create knots in these points that are then recognized when the mesh is made, so that these forces are then applied?

thanks to all of the answers.

 

[volaff]

Sure.
try to look for the "hard point" guide in ansys.
We say that they are "special" points: when you generate automatic mesh a knot will be created in the position defined by the hard point.

an alternative way to insert the knots into "volute" positions is to divide the geometric lines with the lsize command and generate many rectangular/quadrate mesh: I don't know if you understand.

 

[Dare1989]

Thanks for the answer. How do I use hard points? because I used them as follows:

hptcreate,line,80,coord,-18,-ly1,2*hz/lx
hptcreate,line,80,coord,-17,-ly1,3*hz/lx
hptcreate,line,80,coord,-16,-ly1,4*hz/lx
hptcreate,line,80,coord,-15,-ly1.5*hz/lx
hptcreate,line,80,coord,-14,-ly1.6*hz/lx
hptcreate,line,80,coord,-13,-ly1,7*hz/lx

But when I look for the nodes list, I don't find nodes in all hardpoints defined

 

[Dare1989]

In fact, now I have found that I assign the knots to those points. But I would like to "assign" these knots to the keypoints, so that I can define them according to variables. in fact my work will be iterative, since I will have to change the geometry of the structure to optimize the efforts. So I would like that when changing a variable or for example the size of the mesh, you should not go whenever you look for the knots to be able to apply the force to the right knot.

 

[volaff]

I think you should use ansys apdl language if the procedure is iterative

 

[Dare1989]

I understand now, eventually a hard point is like a keypoint and enters the keypoint count. so to appease the force at that point I just need to use fk and put the number corresponding to the hard point.

Thanks for the answers!