Solidworks Simulation Force Required to Enforce Displacement

Simulation Generality
1

Hi everyone,

I'm attaching a picture of my problem to understand a little better. I have two plastic cylinders (contact: no penetration with friction). I would like to know the force needed (taken in two places: arrows on the drawing) to have a displacement of the orange cylinder of 5 cm. How can I do this with a solidworks simulation? I tried to apply a 5 cm displacement to the orange cylinder and fix the cylinder but the solver gave me an error asking me if I wanted to switch to a large displacement. How can I recover my strength afterwards? 

I would also like to take this opportunity to ask you another question. Usually when I'm working on other finite element software, I shrink my mesh until my results converge. Here, Solidworks does it automatically?

 

Thank you very much for your help! 


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2

The displacement seems to me to be the right method, after the solver indicates that the large displacement must be activated does not surprise me, because in a static study, 5cm of displacement is enormous, so either we activate the large displacements, or we change the type of OPUR study passed on a dynamic study.

3 Likes
3

Thank you for this answer! How can I recover my strength over time afterwards? The question I also ask myself is is it worth doing a FEA study when in the end I'm not too interested in deformations. What do you think about using Solidworks Motion? (never used)

4

Indeed, only the method of imposed displacement must be able to work. Otherwise there cannot be a balance of forces as you describe your whole.

What exactly are you looking to achieve?

5

I would just like to know the force necessary for my orange cylinder to move 5 cm knowing that there is a frictional contact with the other cylinder. In reality my system is a little more complicated but I try to model it as simply as possible for the moment to understand.

6

For the orange cylinder to move, the force applied must be greater than the frictional force (plus gravity possibly). After that, unless you want high speeds, the friction being constant, there is no reason for the movement to stop.

Or do you just give an impulse at the beginning?

1 Like
7

All right. The force required will be the same during the move. So I would like to know this force that I have to apply to the orange cylinder so that it reaches a displacement of 5 cm(I feel like I'm not clear) I'm sorry. I can do it by hand in the case of a simple example but in reality my system is not a simple cylinder-cylinder contact (unfortunately I can't post it for confidentiality...). I also wonder if a FEA study is necessary in the end because I am not interested in deformation... What part of solidworks could I use for this since I have Solidworks Premium? 

Thank you very much for your quick answers anyway 

8

On SW I don't know because I don't use it. But I don't think you need a finite element model for this type of calculation.

If you know the coefficient of friction between the 2 cylinders and the contact force, you multiply one by the other and you know the frictional force that prevents you from moving forward.

As soon as you exceed this value, the orange cylinder will start to move forward. If no other effort opposes the movement, it will not stop. So you'll have to wait for the 5 cm of displacement.

After all, it's only a matter of time (sum of forces = m * a).

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9

The problem is that the contact is not simply two cylindrical surfaces. I have tried to simplify the problem here. Which software would you recommend to me? 

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In fact, the form doesn't matter. Neither does the contact surface (in mm²). All that matters is the friction coefficient and the contact force.

Hence my thought that it is not necessary to use calculation software.

11

The coefficient of friction is easily found since it is a plastic plastic contact, on the other hand,  the contact force I don't have...  

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What causes the pieces to touch?

13

Hello

As mentioned in one of your messages, I will use SolidWorks Motion.

With a plastic plastic contact between the two parts, the consideration of gravity, the imposed displacement.

Then you just have to create a graph that takes the value of the force needed to move.

@+

PS: if you need more help on Motion, let us know!

1 Like
14

@Chamade: I sent you a PM;) 

@Coyotte: Thank you for your answer, I'm trying on Motion but so easy because it's the first time I'm using it! I can't apply only one trip? (I feel like I can only apply a force)

 

Thank you very much for your help! 

15

You have to put a linear motor.

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16

After thinking about it, if I understand correctly, what you actually want is not to slide 1 cylinder on top of the other but to fit one cylinder into the other?

In this case, the problem is indeed different because as the cylinder moves the amount of material moved increases and therefore the clamping force with it. This prevents you from going beyond a certain distance for the same effort.

In this case, I would advise you to

- choose a fit between your cylinders (H7m6 for example)

- make a model with the 2 cylinders in real dimensions end-to-end as a starting point

- Lock the end of one cylinder and apply force to the end of the other

It should be possible to do this with SW simulation by prohibiting penetration between the cylinders. For a displacement of several cm, large displacements seem inevitable.

It's a bit of a trial and error method but at first glance it seems to me the most effective.

17

Or if one part is much thinner than the other (so most of the deformation will be there) you can maybe try to model only that one by applying pressure in the interlocking area until you have a deformation of the value of the fit between the parts.

If you know the value of the friction between the parts, you can deduce the force to be applied to compensate for this friction.