Building assemblies with inserted parts

[Vorony]

Just a general question. I am currently working on a bone (femur) model which will have 2 titanium rods inserted through the middle of the bone. I am then exporting the file to MSC Visual Nastran to perform stress analyses on the model. My question, however, pertains to the insertion of the rods in SolidWorks. Can I just insert the rod in the bone model without making a cut through the bone to accomodate the rod? Or do I need to make a cut through the bone with the same coordinates as the rod so that the rod essentially fits into the cut? I am relatively new to SolidWorks, so any help would be greatly appreciated. One other thing... when I mate the components (bone and rods), can I use the origin of each component for the mate, or should it be a specific face of each part? The bone model is very complex and it would be difficult to choose the exact face to mate with on the bone.

 

[Mandrake22]

You could simply locate and mate the rods into the bone but it seems to me that wouldn't give the most valid FEA results.
What is done in the real world application? Are holes drilled into the bone for the rods? If so, then I would suggest that your model have the same features.
The easiest way to mate the parts would then be to select the cylindrical face of the hole and the cooresponding cylindrical face of the rod and apply a concentric mate. A distance mate from appropriate features of the parts would then locate the rod axially within the bone.
The non-uniform nature of the bone model may require a bit of trial and error to create a new plane for the hole feature.

 

[macPT]

Vorony

SW will not bother if you mate parts with interference (it will know that the interference exists and you can chek it in the tOOLS menu). So you don't need to reproduce the cut into the bone (but that should be the correct modeling technique).

You must pay attention to some engineering data (like weigth, inertia, ...) that can be wrong cause by the extra material of the undone cut.

To assemble correctly you must have referencies (faces, planes, axis, points). Maybe you should create the needed extra referencies in the bone part (planes, axes and points) because of the geometry of the bone, wich can make dificult to find faces good for mating.

Regards

 

[TheTick]

Once you have the rod positioned where you want it with respect to the bone, you can cut the interference volume out of the bone.

1.) First, make the bone the active part in the assembly by right-clicking the bone in the assembly tree and selecting "Edit Part".

2.) Then, remove the rod volume from the bone using "Insert --> Feature --> Cavity".

If the ladies don't find you handsome, they should at least find you handy.

 

[SnowCrash]

TheTick told you how to do this. It is one of my everyday tools. Be sure the parts are prperly located and mated.
Another tip would be to make configurations of the femur with the holes drilled and not drilled for other analysis.
--
Crashj

 

[Vorony]

Ahhhh The Tick's suggestion worked perfectly. I used the same cavity feature to cut out the bone canal as well. Thanks a lot for the help!