Hello
In Solidworks Premium, I want to simulate the deformations of a part under stress (zip joint).
test_0.zip (232.3 KB)
Normally, if you press on the top of the ' tripod ', the feet should spread outwards.
I just get a squish. The feet remain fixed.
… And when I replace the rounding with a surface and specify the local contact interactions, only one foot moves:
Hello;
Your system is naturally unstable, it won't be easy to get consistent results from it.
In your place, I will add a constraint of displacement along a coaxial axis between your support surface (the ground) and the center of the surface of your tripod.
Hello
You would have more possible answers by offering your model in an older version than SW2025.
As of the 2024 release, Solidworks offers the " Save As " option in an older version...
Thank you for your answers.
@Maclane :
Where is this constraint of displacement? I've tried a whole bunch of ' forced displacements ' but I don't see how to limit the displacement axially.
@m_blt :
Files in 2024:
test_2.zip (6.1 MB)
Hello
As the part is symmetrical, calculating a1/3 of the model should solve a lot of stability problems / uncontrolled displacements.
Otherwise SW should not have any problem managing the toroidal / plane contact normally.
NB; No need to model the room below if you can consider an infinitely rigid plane. It will lighten the model/calculation
@froussel :
Yes, I could totally simulate part of the model but since the overall answer is strange, I have no confidence in the result of a segment...
I'll try anyway!
Hello @Walter_POOT ,
As indicated in a previous answer, the problem comes from the fact that the " contacts " of the tripod with the base do not ensure its balance. It can slide on the map, hence the visualization of movements.
This is true even if the force applied to the upper surface is vertical, and does not induce a component causing this displacement. The fault lies in the discretization of the model.
The answer is to impose displacement constraints to immobilize the tripod. Not always easy...
A simpler solution is to introduce a slight " stiffness " from the outside to ensure balance.
This stiffness is enough to ensure balance without introducing significant effort...
Note that introducing friction into the definition of the contact can also solve the problem.
Thank you all and especially @Walter_POOT !
Indeed, by imposing a reference geometry the displacement becomes coherent (to be verified by calculations).
Hello, it was also the interest to switch to 1/3 of a model for this simulation: the part would never have been able to move on the plane.
Beware of this constraint of movement imposed in 2 points, which justifies my remark in the previous message:
Constrain zero displacement parallel to the plane of the base at two points Requires the distance between them to remain constant when loading.
In this case, the upper part of the tripod is very rigid, which makes the result close to the exact solution.
But if the same rule is applied to two other points, as in the illustration below, the distance between the two feet is kept constant.
And here, although the principle is the same, the result is very different: little deformation of the two left feet, and much more significant deformation of the right foot.
In fact, the global contact as defined in the interactions leaves the tripod the possibility of a plane motion (RotY, TrslX, TrslZ), i.e. 3 degrees of freedom. It therefore requires 3 travel conditions to immobilize it, while the proposed model imposes four, (TrslX, TrslZ) at two points.
My proposal: use two diametrically opposed points to preserve the symmetry of the model, with (TrslX, TrslZ) for the first and only (TrslX) for the second.
The results are:
Hey there,
I took a look at your simulation setup and I think I understand the issue you’re facing. When you’re pressing down on the top of the tripod, you’re expecting the legs to spread outwards—kind of like how the base of a flagpole might behave if it wasn’t properly anchored. (Funny enough, reminds me of how some American Flags on flexible poles bend under wind stress—similar concept, different scale!)
From your description, it sounds like the boundary conditions may be over-constraining the feet. If the feet are being « squished » but not moving outward, check if:
If you’re using SolidWorks Premium, try using nonlinear static analysis if the deformation is expected to be large.
Feel free to share more screenshots or your setup details—I’m happy to help more.
Best,
Nancy Morgan
