Learning Forum

[Dan s]

Hello I am working on VM17 and I have set everything up according to the image. Below

However I am having trouble setting up the hinged support. I was told by my teacher that I needed to use "Fixed Rotation" which I added and set the Rotation of Y,X to fixed and left Z free. However I am getting an error saying there arent enough constraints. Any advice on how to set it up correctly? I tried adding various supports to the edges, but i am just unsure on how to set it up.

[ErKo]

Hi

See that vm17 example in our help and the commands used (D command) - hinged supoort is all rotations free, and displacements UX=UY=UZ=0.

All the best

Erik

[Dan s]

Hey Erik, i am not sure what you exactly mean. Could you elaborate more?
Thanks

[ErKo]

Hi

I will try to explain even more in detail.

Let’s start from the beginning.

Shell elements so the ones you use now in workbench mechanical, are called shell181(4 nodes/element) or shell281 (8 nodes/element).

They have by default six degrees of freedom at each node: translations in the x, y, and z directions, and rotations about the x, y, and z-axes.

So a hinged support as seen in vm17 example, has on the hinged edge, the translations in the x, y, and z directions = 0 , and free rotations about the x, y, and z-axes.

To create that hinged boundary condition (BC), you pick that edge and insert a Displacement BC,  and set X, Y, Z Component = 0. See here how to set up such a displacement BC. /courses/index.php/courses/high-resolution-fe-model-of-bone/lessons/physics-setup-lesson-5-14/topic/4-boundary-conditions/

So, that is how to set that hinged support up.

To close of this post, in your model you have a Fixed Rotation BC. You need to remove this Fixed Rotation. Now you might as why? Because as we said, on a hinged edge all rotations about the x, y, and z-axes are free.

Erik